Electrical Standard

Federal RegisterApr 5, 2004

Ask Donna

What actually matters in this document.

Text

DEPARTMENT OF LABOR

Occupational Safety and Health Administration

29 CFR Part 1910

[Docket No. S-108C]

RIN 1218-AB95

Electrical Standard

AGENCY:

Occupational Safety and Health Administration, Labor.

ACTION:

Proposed rule.

SUMMARY:

The Occupational Safety and Health Administration (OSHA) is proposing to revise the general industry electrical installation standard found in Subpart S of 29 CFR Part 1910. The Agency has determined that electrical hazards in the workplace pose a significant risk of injury or death to employees, and that the requirements in the revised standard, which draw heavily from the 2000 edition of the National Fire Protection Association's (NFPA) Electrical Safety Requirements for Employee Workplaces (NFPA 70E), and the 2002 edition of the National Electrical Code (NEC), are reasonably necessary to provide protection from these hazards. This proposed rule focuses on safety in the design and installation of electric equipment in the workplace. This revision will provide the first update of the installation requirements in the general industry electrical installation standard since 1981.

OSHA is also proposing to replace the reference to the 1971 National Electrical Code in the mandatory appendix to the powered platform standard with a reference to OSHA's electrical installation standard.

DATES:

Submit written hearing requests and comments regarding this proposal, including comments on the information-collection determination described in Section XI. of the preamble (OMB Review under the Paperwork Reduction Act of 1995), by the following dates:

Hard Copy:

Your hearing requests and comments must be submitted (postmarked or sent) by June 4, 2004.

Facsimile and electronic transmission:

Your hearing requests and comments must be sent by June 4, 2004.

Please see the section entitled

SUPPLEMENTARY INFORMATION

for additional information on submitting written comments and hearing requests.

ADDRESSES:

Regular mail, express delivery, hand-delivery, and messenger service:

Submit three copies of hearing requests, comments, and attachments to the OSHA Docket Office, Docket No. S-108C, Room N-2625, U.S. Department of Labor, 200 Constitution Avenue, NW, Washington, DC 20210; telephone (202) 693-2350. OSHA Docket Office and Department of Labor hours of operation are 8:15 a.m. to 4:45 p.m., e.s.t.

Please note that security-related problems may result in significant delays in receiving comments and other materials by regular mail. Telephone the OSHA Docket Office at (202) 693-2350 for information regarding security procedures concerning delivery of materials by express delivery, hand delivery, and messenger service.

Facsimile:

Transmit hearing requests and comments (including attachments) consisting of 10 or fewer pages by facsimile to the OSHA Docket Office at (202) 693-1648. You must include the docket number of this notice, Docket No. S-108C, in your comments.

Electronic:

Submit comments electronically through the Internet at

http://ecomments.osha.gov.

All comments and submissions will be available for inspection and copying in the OSHA Docket Office at the address above. Most comments and submissions will be posted on OSHA's Web page (

http://www.osha.gov

). Contact the OSHA Docket Office at (202) 693-2350 for information about materials not available on the OSHA Web page and for assistance in using this Web page to locate docket submissions. Because comments sent to the docket or to OSHA's Web page are available for public inspection, the Agency cautions interested parties against including in these comments personal information such as social security numbers and birth dates.

FOR FURTHER INFORMATION CONTACT:

For general information and press inquiries, contact Mr. George Shaw, Office of Communications, Room N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue, NW., Washington, DC 20210; telephone (202) 693-1999. For technical inquiries, contact Ms. Belinda Cannon, Directorate of Standards and Guidance, Room N-3609, OSHA, U.S. Department of Labor, 200 Constitution Avenue, NW., Washington, DC 20210; telephone (202) 693-2083.

For additional copies of this

Federal Register

notice, contact OSHA, Office of Publications, U.S. Department of Labor, Room N-3101, 200 Constitution Avenue, NW., Washington, DC 20210; telephone (202) 693-1888. Electronic copies of this

Federal Register

notice, as well as news releases and other relevant documents, are available at OSHA's web page on the Internet at

http://www.osha.gov.

SUPPLEMENTARY INFORMATION:

I. Introduction

This proposed rule would revise OSHA's existing standard for electrical installations, which is contained in §§ 1910.302 through 1910.308 of Subpart S, with relevant definitions in § 1910.399. It would apply, as the existing standard does, to employers in general industry and in maritime employment.

OSHA undertook the project to revise Subpart S for two major reasons. First, the Agency wanted the rule to reflect the most current practice and technology in the industry. The current rule is based on a national consensus standard, the 1979 edition of Part I of NFPA 70E, entitled

Standard for Electrical Safety Requirements for Employee Workplaces.

That consensus standard has been updated several times since OSHA last revised its electrical installation requirements in 1981. The proposed rule being published today relies heavily on the 2000 edition of NFPA 70E. Second, in proposing this rule, OSHA is responding to requests from stakeholders that the Agency revise Subpart S so that it conforms with the most recent editions of NFPA 70E and the National Electrical Code.

These stakeholders argued that interested members of the public have had substantial input into the content of NFPA 70E, and that industry is complying with that standard in its current form. The revised regulation will be more flexible and efficient for stakeholders and small businesses, while maintaining needed protections for workers.

See, for example, letters from: Judith Gorman, Managing Director of the Institute of Electrical and Electronic Engineers; George D. Miller, President and Chief Executive Officer of the National Fire Protection Association; Frank K. Kitzantides, Vice President of Engineering at the National Electrical Manufacturers Association; and Kari P. Barrett, Director of Regulatory and Technical Affairs, Plant Operations, at the American Chemistry Council.

OSHA's existing electrical standard in §§ 1910.302 through 1910.308 is based on the 1979 edition of NFPA 70E, which is a national consensus standard developed by a cross section of industry, labor, and other allied interests. Consensus standards like the National Electrical Code (NEC) and NFPA 70E provide nationally recognized safe electrical installation requirements. Additionally, the consensus process used in developing NFPA 70E, Part 1 of which is based on the NEC, ensures that requirements contained in that standard are current and at the forefront of electrical safety technology. Because the primary objective of this revision of Subpart S is to update the standard to recognize, and

in some cases require, the most current electrical safety technology, OSHA believes that the 2000 edition of NFPA 70E should be the foundation of the proposal.

The remainder of the preamble discusses the background of the proposal; the history of Subpart S and the development of this proposal; the statutory considerations; a summary and explanation of the proposed standard; the Preliminary Economic and Regulatory Flexibility Analysis; the information collections associated with the rule; and other miscellaneous topics. The outline of the preamble is as follows:

I. Introduction

II. Background

III. History of the Rule

IV. Legal Authority

V. Summary and Explanation of the Proposed Rule

VI. Preliminary Economic and Regulatory Screening Analysis

VII. State Plan Standards

VIII. Environmental Impact Analysis

IX. Unfunded Mandates

X. Federalism

XI. OMB Review under the Paperwork Reduction Act of 1995

XII. Public Participation

XIII. List of Subjects

XIV. Authority and Signature

II. Background

A. Hazards Associated With Electricity

Electricity is widely recognized as a serious workplace hazard, exposing employees to electric shock, burns, fires, and explosions. According to the Bureau of Labor Statistics, 289 employees were killed by contact with electric current in 2002.

Other employees have been killed or injured in fires and explosions caused by electricity.

“2002 Census of Fatal Occupational Injuries,” Table A-9, Bureau of Labor Statistics,

http://www.bls.gov/iif/oshwc/cfoi/cftb0163.pdf.

It is well known that the human body will conduct electricity. If direct body contact is made with an electrically energized part while a similar contact is made simultaneously with another conductive surface that is maintained at a different electrical potential, a current will flow, entering the body at one contact point, traversing the body, and then exiting at the other contact point, usually the ground. Each year many workers suffer pain, injuries and death from such electric shocks.

Burns suffered in electrical accidents can be very serious. These burns may be of three basic types: electrical burns, arc burns, and thermal contact burns. Electrical burns are the result of the electric current flowing in the tissues, and may be either skin deep or may affect deeper layers (such as muscles and bones) or both. Tissue damage is caused by the heat generated from the current flow; if the energy delivered by the electric shock is high, the body cannot dissipate the heat and the tissue is burned. Typically, such electrical burns are slow to heal. Arc burns are the result of high temperatures produced by electric arcs or by explosions close to the body. If the current involved is great enough, these arcs can cause injury or can start a fire. Fires can also be created by overheating equipment or by conductors carrying too much current. Extremely high-energy arcs can damage equipment, causing fragmented metal to fly in all directions. In atmospheres which contain explosive gases or vapors or combustible dusts, even low-energy arcs can cause violent explosions. These burns are similar to burns and blisters produced by any high temperature source. Finally, thermal contact burns are those normally experienced from the skin contacting hot surfaces of overheated electric conductors, conduits, or other energized equipment. All types of burns may be produced simultaneously.

Current through the body, even at levels as low as 3 milliamperes, can also cause injuries of an indirect or secondary nature in which involuntary muscular reaction from the electric shock can cause bruises, bone fractures and even death resulting from collisions or falls.

B. Nature of Electrical Accidents

Electrical accidents, when initially studied, often appear to be caused by circumstances that are varied and peculiar to the particular incidents involved. However, further consideration usually reveals the underlying cause to be a combination of three possible factors: work involving unsafe equipment and installations; workplaces made unsafe by the environment; and unsafe work performance (unsafe acts). The first two factors are sometimes combined and simply referred to as unsafe conditions. Thus, electrical accidents can be generally considered as being caused by unsafe conditions, unsafe acts, or, in what is usually the case, combinations of the two. It should also be noted that inadequate maintenance can cause equipment or installations which were originally considered safe to deteriorate, resulting in an unsafe condition.

Some unsafe electric equipment and installations can be identified, for example, by the presence of faulty insulation, improper grounding, loose connections, defective parts, ground faults in equipment, unguarded live parts, and underrated equipment. The environment can also be a contributory factor to electrical accidents in a number of ways. Environments containing flammable vapors, liquids or gases; areas containing corrosive atmospheres; and wet and damp locations are some unsafe environments affecting electrical safety. Finally, unsafe acts include the failure to deenergize electric equipment when it is being repaired or inspected, the use of obviously defective and unsafe tools, or the use of tools or equipment too close to energized parts.

C. Protective Measures

There are various general ways of protecting employees from the hazards of electric shock, including insulation and guarding of live parts. Insulation provides an electrical barrier to the flow of current. To be effective, the insulation must be appropriate for the voltage, and the insulating material must be undamaged, clean, and dry. Guarding prevents the employee from coming too close to energized parts. It can be in the form of a physical barricade, or it can be provided by installing the live parts out of reach from the working surface. (This technique is known as “guarding by location.”)

Grounding is another method of protecting employees from electric shock; however, it is normally a secondary protective measure. To keep guards or enclosures at a common potential with earth, they are connected, by means of a grounding conductor, to ground. In addition, grounding provides a path of low impedance and of ample capacity back to the source to pass enough current to operate the overcurrent devices in the circuit. If a live part accidentally comes in contact with a grounded enclosure, current flow is directed back to earth, and the circuit protective devices (for example, fuses and circuit breakers) can interrupt the circuit.

If it draws too much current, electric equipment can overheat, which can result in fires.

Protecting electric equipment from overcurrent helps prevent this from happening.

Overheating can also lead to electric shock hazards if the insulation protecting a conductor melts.

Designing and installing equipment to protect against dangerous arcing and overheating is also important in preventing unsafe conditions that can lead to fires, high energy electric arcs, and explosions. Employers and employees cannot usually detect

improperly designed or rated equipment. Thus, OSHA relies on third-party testing and certification of electric equipment to ensure proper electrical design. This helps ensure, for example, that equipment will not overheat during normal operation and that equipment designed for use in a hazardous location will not cause a fire or explosion. It also helps ensure that equipment is appropriately rated and marked, allowing employees designing electrical installations and installing electric equipment to select equipment and size conductors in accordance with those ratings.

Many of the requirements in OSHA's electrical standards in turn depend on accurate ratings on equipment.

Electric equipment is typically rated for use with certain voltages and current. For example, an electric hair dryer might be rated at 125 volts, 1875 watts. The voltage rating indicates the maximum voltage for which the equipment is rated. The wattage rating indicates how much power the equipment will draw when connected to a circuit at the maximum voltage. The current drawn by the equipment is the wattage rating divided by the voltage rating. Thus, the circuit voltage (120 volts, nominal) is less than the maximum rated voltage of the hair dryer (125 volts), and the circuit is rated for the current the equipment will draw (1875 watts/125 volts = 15 amperes). Thus, the hair dryer would be suitable for use on a 120-volt circuit capable of safely carrying 15 amperes.

These protective measures help ensure the safe installation of electric equipment and are prescribed by the requirements presently contained in 29 CFR Part 1910, Subpart S. Addressing common unsafe conditions, these rules cover such safety considerations as guarding and insulation of live parts, grounding of equipment enclosures, and protection of circuits from overcurrent. This rulemaking would update those requirements to make them consistent with the latest edition of NFPA 70E. This revision would better protect employees by recognizing the latest techniques in electrical safety and by requiring installations to incorporate those techniques whenever necessary.

III. History of the Rule

On February 16, 1972, OSHA incorporated the 1971 edition of the National Fire Protection Association's (NFPA)

National Electrical Code

(NEC), NFPA 70-1971, by reference as its electrical standard for general industry (37 FR 3431). The Agency followed the procedures outlined in Section 6(a) of the Occupational Safety and Health Act of 1970 (29 U.S.C. 655), which directed the Secretary to adopt existing national consensus standards as OSHA standards within 2 years of the effective date of the Occupational Safety and Health Act (OSH Act). In incorporating the 1971 NEC by reference, OSHA made the entire 1971 NEC applicable to all covered electrical installations made after March 15, 1972. For covered installations made before that date, OSHA listed about 20 provisions from the 1971 NEC that applied. No other provisions of the 1971 NEC applied to these older installations. Thus, older installations were “grandfathered” so that they did not need to meet most of the requirements in the consensus standard.

On January 16, 1981, OSHA revised its electrical installation standard for general industry (46 FR 4034). This revision replaced the incorporation by reference of the 1971 National Electrical Code with relevant requirements from Part I of the 1979 edition of NFPA 70E.

The revision simplified and clarified the electrical standard and updated its provisions to match the 1978 NEC (the latest edition available at the time). The standard was written to reduce the need for frequent revision and to avoid technological obsolescence. These goals were achieved—NFPA 70E had only minor changes over its initial 15 years of existence. The first substantial changes were introduced in the 1995 edition of NFPA 70E.

OSHA added electrical safety-related work practice requirements to Subpart S on August 6, 1990 (55 FR 31984). Those requirements were based on Part II of 1988 edition of NFPA 70E. However, the current rulemaking makes no changes to the safety-related work practice provisions in Subpart S.

The latest edition of NFPA 70E, the 2000 edition, contains a number of significant revisions, including a new, alternative method for classifying and installing equipment in Class I hazardous locations (see preamble Section V. F. “Zone Classification,” below). NFPA has recommended that OSHA revise its general industry electrical standards to reflect the latest edition of NFPA 70E, arguing that such a revision would provide a needed update to the OSHA standards and would better protect employees. The present proposal responds to NFPA's recommendations with regard to installation safety. It also reflects the Agency's commitment to update its electrical standards, keep them consistent with NFPA standards, and ensure that they appropriately protect employees. The Agency intends to extend this commitment by using NFPA 70E as the basis for future revisions to its electrical safety-related work practice requirements and new requirements for electrical maintenance and special equipment.

IV. Legal Authority

The purpose of the Occupational Safety and Health Act of 1970 (OSH Act), 29 U.S.C. 651

et seq.

, is “to assure so far as possible every working man and woman in the nation safe and healthful working conditions and to preserve our human resources.” 29 U.S.C. 651(b). To achieve this goal, Congress authorized the Secretary of Labor to promulgate and enforce occupational safety and health standards. 29 U.S.C. 655(b) and 654(b).

A safety or health standard “requires conditions, or the adoption or use of one or more practices, means, methods, operations, or processes, reasonably necessary or appropriate to provide safe or healthful employment or places of employment.” 29 U.S.C. 652(8). A standard is reasonably necessary or appropriate within the meaning of Section 652(8) if:

• A significant risk of material harm exists in the workplace and the proposed standard would substantially reduce or eliminate that workplace risk;

• It is technologically and economically feasible;

• It is cost effective;

• It is consistent with prior Agency action or supported by a reasoned justification for departing from prior Agency action;

• It is supported by substantial evidence; and

• In the event the standard is preceded by a consensus standard, it is better able to effectuate the purposes of the OSH Act than the standard it supersedes.

International Union, UAW

OSHA (LOTO II),

37 F.3d 655 (D.C. Cir. 1994).

OSHA has generally considered an excess risk of 1 death per 1000 employees over a 45-year working lifetime as clearly representing a significant risk.

Industrial Union Dept.

American Petroleum Institute (Benzene),

448 U.S. 607, 646 (1980);

International Union

Pendergrass (Formaldehyde),

878 F.2d 389, 393 (D.C. Cir. 1989);

Building and Construction Trades Dept., AFL-CIO

Brock (Asbestos),

838 F.2d 1258, 1264-65 (D.C. Cir. 1988).

A standard is considered technologically feasible if the protective measures it requires already exist, can be brought into existence with available technology, or can be created with technology that can reasonably be expected to be developed.

American Textile Mfrs. Institute

OSHA (Cotton Dust),

452 U.S. 490, 513 (1981),

American Iron and Steel Institute

OSHA (Lead II),

939 F.2d 975, 980 (D.C. Cir. 1991).

OSHA generally considers a standard to be cost effective if the protective measures it requires are the least costly of the available alternatives that achieve the same level of protection.

Cotton Dust,

453 U.S. at 514, n.32;

International Union, UAW

OSHA (LOTO III),

37 F.3d 655, 668 (D.C. Cir. 1994).

All OSHA standards must be highly protective, and, where practical, “expressed in terms of objective criteria and of the performance desired.”

LOTO III,

37 F.3d at 669. Finally, the OSH Act requires that when promulgating a rule that differs substantially from a national consensus standard, OSHA must explain why the promulgated rule is a better method for effectuating the purpose of the Act. 29 U.S.C. 655(b)(8). As discussed earlier, OSHA is using NFPA 70E as the basis for its proposed rule, with some modifications as necessary for regulatory and enforcement purposes.

Electricity has long been recognized as a serious workplace hazard exposing employees to dangers such as electric shock, electrocution, fires, and explosions. The 100-year-long history of the National Electrical Code, originally formulated and periodically updated by industry consensus, attests to this fact. The NEC has represented the continuing efforts of experts in electrical safety to address these hazards and provide standards for limiting exposure in all electrical installations, including workplaces. OSHA has determined that electrical hazards in the workplace pose a significant risk of injury or death to employees, and that this proposed standard, which draws heavily on the experience of the NEC, is reasonably necessary to provide protection from these hazards.

According to the U.S. Bureau of Labor Statistics, between 1992 and 2002, an average of 295 workers died per year from contact with electric current, and, between 1992 and 2001, an average of 4,309 workers lost time away from work because of electrical injuries.

Overall, there has been a downward trend in injuries and illnesses, but the percentage of decline has varied from year to year. From 1992 to 2001, the number of injuries involving days away from work decreased by 29 percent. From 1992 to 2002, the number of deaths decreased by 9 percent. This downward trend is due, in major part, to 30 years of highly protective OSHA regulation in the area of electrical installation, based on the NEC and NFPA 70E standards. The proposal would carry forward most of the existing requirements for electrical installations, with the new and revised requirements intended as fine tuning, introducing new technology along with other improvements in safety. If employers comply with the proposal, they will prevent unsafe electrical conditions from occurring. Thus, OSHA expects this downward trend in injuries to continue.

The Survey of Occupational Injuries and Illnesses

and the

Census of fatal occupational injuries, http://www.bls.gov/iif/home.htm#tables.

While the number of deaths and injuries associated with electrical hazards has declined, contact with electric current still poses a significant risk to employees in the workplace. This proposed rule will help further reduce the number of deaths and injuries associated with electrical hazards by providing additional requirements for installation safety and by recognizing alternative means of compliance.

V. Summary and Explanation of the Proposed Rule

A. Scope

Existing §§ 1910.302 through 1910.308 of Subpart S apply to electrical installations and utilization equipment used and installed in workplaces in general industry and in shipyard employment, longshoring, and marine terminals. These sections do not apply to the following types of installations:

(1) Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles;

(2) Installations underground in mines;

This exception was incorporated into the current OSHA standard solely to be consistent with language used in the NEC and NFPA 70E. However, it should be noted that OSHA does not have jurisdiction over mines in general, regardless of whether the mining activity takes place above ground or underground. Under the Mine Safety and Health Act (MSH Act) (30 U.S.C. 801

et seq.

), the Mine Safety and Health Administration (MSHA) regulates safety and health in mines. The MSH Act defines “mine” very broadly as:

(h)(1) “coal or other mine” means (A) an area of land from which minerals are extracted in nonliquid form or, if in liquid form, are extracted with workers underground, (B) private ways and roads appurtenant to such area, and (C) lands, excavations, underground passageways, shafts, slopes, tunnels and workings, structures, facilities, equipment, machines, tools, or other property including impoundments, retention dams, and tailings ponds, on the surface or underground, used in, or to be used in, or resulting from, the work of extracting such minerals from their natural deposits in nonliquid form, or if in liquid form, with workers underground, or used in, or to be used in, the milling of such minerals, or the work of preparing coal or other minerals, and includes custom coal preparation facilities. In making a determination of what constitutes mineral milling for purposes of this chapter, the Secretary shall give due consideration to the convenience of administration resulting from the delegation to one Assistant Secretary of all authority with respect to the health and safety of miners employed at one physical establishment;

(2) For purposes of subchapters II, III, and IV of this chapter, “coal mine” means an area of land and all structures, facilities, machinery, tools, equipment, shafts, slopes, tunnels, excavations, and other property, real or personal, placed upon, under, or above the surface of such land by any person, used in, or to be used in, or resulting from, the work of extracting in such area bituminous coal, lignite, or anthracite from its natural deposits in the earth by any means or method, and the work of preparing the coal so extracted, and includes custom coal preparation facilities;

For further information, see the Interagency Agreement between MSHA and OSHA (

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=MOU&p_ id=222).

(3) Installations of railways for generation, transformation, transmission, or distribution of power used exclusively for operation of rolling stock or installations used exclusively for signaling and communication purposes;

(4) Installations of communication equipment under the exclusive control of communication utilities, located outdoors or in building spaces used exclusively for such installations; and

(5) Installations under the exclusive control of electric utilities for the purpose of communication or metering; or for the generation, control, transformation, transmission, and distribution of electric energy. These exempted installations must be located in buildings used exclusively by utilities for such purposes or located outdoors on property owned or leased by the utility or on public highways, streets, roads, etc., or outdoors by established rights on private property.

These exempted installations present special design considerations that are not adequately addressed in Subpart S. For example, electric power transmission and distribution installations are typically installed where unqualified persons will not have access to them, and the only employees working on them are highly trained and skilled. Additionally, public safety considerations demand that these installations be capable of quick repair when weather or equipment failure disrupt electrical service. The National Electrical Safety Code (ANSI/IEEE C2), which is developed by experts in electric power generation, transmission, and distribution, contains design and installation requirements applicable to electric power transmission and distribution systems. Section 1910.269 contains OSHA's standard for the maintenance of electric power generation, transmission, and distribution installations. While it consists mostly of work-practice

requirements, it does contain several installation requirements. For example, § 1910.269(u)(4) and (v)(4) cover guarding of rooms containing electric supply equipment in electric power generating stations and substations, respectively. OSHA believes that any installation requirements for electric power generation, transmission, and distribution systems belong in § 1910.269 rather than in Subpart S.

Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles (other than mobile homes and recreational vehicles) are designed to be transportable.

These transportability considerations make many of the design requirements in Subpart S irrelevant, at best, or infeasible, at worst. For example, attaching the grounded circuit conductor and the equipment grounding conductor to a permanent grounding electrode on a transportable wiring system is generally not feasible. Thus, the provisions of proposed § 1910.304(g)(1), which contains requirements for grounding electrical systems, are inappropriate for the wiring of ships, watercraft, railway rolling stock, aircraft, or automotive vehicles. By contrast, however, wiring that is not a part of the wiring of the ship, watercraft, railway rolling stock, aircraft, or automotive vehicle would be covered by Subpart S, as appropriate. For example, a portable electric drill carried into the cargo area of a truck would be covered by Subpart S if it is plugged into the wiring of a service station.

Although the wiring of recreational vehicles and mobile homes is transportable, it is also designed to be attached to specially designed, permanently installed power distribution outlets. This type of hybrid system must be designed for both permanent and transportable uses.

In regard to ships, there has been some confusion about whether the “exemption” applies to all wiring or electrical installations brought on board a vessel during construction, overhaul, or repair, even when the wiring is supplied by shore-based electric power—or whether it only applies to the ships' own wiring. OSHA is hereby clarifying its position.

The “exempted” types of installations in both the current and proposed standards are identical to those “exempted” by the National Electrical Code and NFPA 70E, which form the basis of both. Installations covered under the existing standard would continue to be covered under the proposal. For example, in longshoring operations and related employments, this proposal would apply to electrical installations aboard vessels only if they are shore-based as stated in § 1918.1(b)(3). Electrical installations in marine terminals are covered under Subpart S, as noted in § 1917.1(a)(2)(iv). (The marine terminals standard in Part 1917 applies to the loading, unloading, movement or other handling of cargo, ship's stores or gear within the terminal or into or out of any land carrier, holding or consolidation area, and any other activity within and associated with the overall operation and function of the terminal. This includes the use and routine maintenance of facilities and equipment and cargo transfer accomplished with the use of shore-based material handling devices. See § 1917.1(a).)

Section 1910.5 governs how the general industry electrical standards apply to shipyard employment. According to § 1910.5(c)(2), the general standards in Part 1910 apply to the extent that no industry-specific standard (such as Subpart K of Part 1926 for construction) applies to the “same condition, practice, means, method, operation, or process.” Part 1915 contains few requirements related to electrical safety. Paragraph (b) of § 1915.93 contains four such requirements, for grounding of vessels, the safety of the vessel's wiring, overcurrent protection, and guarding of infrared heat lamps. Section 1915.92 contains provisions on electric lighting, and § 1915.132 contains requirements on portable electric tools. Section 1915.181 contains electrical safety-related work practices for deenergizing electric circuits and protecting employees against contact with live parts during electrical work. In addition, Part 1915 contains several other miscellaneous electrical safety-related work practices and electrical design requirements. These provisions continue to apply in lieu of any corresponding requirements in Subpart S of Part 1910. Conversely, where there is no specific standard for shipyard employment in Part 1915, Subpart S of Part 1910 applies.

It should be noted that, unlike the shipyard employment standards, OSHA's construction standards have a comprehensive electrical installation standard in Subpart K of Part 1926, which covers all aspects of electrical safety that are addressed in the electrical installation standard for general industry. Thus, none of the electrical installation requirements in Subpart S of Part 1910 apply in construction.

As noted earlier, Subpart S does not cover installations in ships, but it does cover installations used on ships if the installation is shore-based (that is, not part of the vessel's internal electrical system). Thus, § 1910.303(g)(2) (guarding live parts) applies to the wiring of the shipyard and to any wiring taken onto the ship when it is supplied by the shipyard wiring. It does

not

apply to the ship's wiring. The proposed rule does not change this scope of coverage. However, OSHA invites comments on whether it needs to clarify this coverage further.

B. Grandfather Clause

The proposal, as does the current rule, exempts older electrical installations from meeting some of the provisions of the Design Safety Standards for Electrical Systems (that is, §§ 1910.302 through 1910.308). The extent to which OSHA's electrical installation standard applies depends on the date the installation was made. Older installations must meet fewer requirements than newer ones. The proposal's grandfathering of older installations, contained in paragraph (b) of proposed § 1910.302, is patterned after the current standard's grandfather provisions in existing § 1910.302(b). Most of the new provisions contained in the proposed rule would only apply prospectively, to installations made after the effective date of the final rule.

The following paragraphs explain proposed § 1910.302(b) in the following order: paragraph (b)(1), requirements applicable to all installations; paragraph (b)(4), requirements applicable only to installations made after the effective date of the revised standard; paragraph (b)(3), requirements applicable only to installations made after April 16, 1981; and paragraph (b)(2), requirements applicable only to installations made after March 15, 1972.

Requirements applicable to all installations.

Paragraph (b)(1) of proposed § 1910.302 contains a list of provisions that would apply to all installations, regardless of when they were designed or installed. The few requirements in this short list are so essential to employee safety that even the oldest electrical installations must be modified, if necessary, to meet them. The list is unchanged from the current standard, except for the addition of the zone classification system and a documentation requirement from proposed § 1910.307. As discussed in more detail later in this section of the preamble, the only substantial new provisions being proposed in § 1910.307 are: (1) New requirements in § 1910.307(g) pertaining to electric equipment installed in Class I hazardous locations if the employer chooses to use the zone classification system and (2) a new requirement in § 1910.307(b) for employers to document the extent of each hazardous location. This second provision applies

to older installations only if the employer is using the zone classification system.

The new requirements pertaining to zone classification in proposed § 1910.307(g) provide employers with an alternative installation method that the current standard does not permit.

Thus, applying these provisions to older installations would give employers greater flexibility without imposing any new costs.

See the discussion under the heading “Zone Classification” for an explanation of the zone classification system and its differences from the current standard's division classification system.

Paragraph (b) of § 1910.307 proposes a new requirement that employers document areas designated as hazardous (classified) locations. This requirement would ensure that the employer has records of the extent and classification of each such area. The documentation would help employers determine what type of equipment was needed in these locations and would inform employees of the need for special care in the maintenance of the electric equipment installed there. OSHA has carefully considered the need to document these areas and has tried to balance that need with the extensive burden that would be placed on employers who would have to survey and document their existing hazardous locations.

The current standard's division classification system has been in place for many years, and most employers and inspection authorities are familiar with the boundaries for Class I, Division 1 and Class I, Division 2 locations. An employee servicing equipment in a Class I, Division 1 or 2 location can obtain this information relatively easily even if the employer has not documented the boundaries. Accordingly, OSHA believes that the benefit of documenting existing hazardous locations installed using the division classification system would be minimal. Therefore, for employers using the division system, OSHA is proposing to require documentation of boundaries only for new installations made after the effective date of the standard. Employers would not need to document existing division-classified systems.

On the other hand, the zone classification system is relatively new. Most employers are not familiar with this system and have little experience determining how to draw the boundaries between the three zones. Relatively few NFPA or industry standards provide specifications for placing those boundaries. Furthermore, the existing OSHA electrical standard recognizes only installations made in accordance with the division classification system, not the zone classification system. Any existing installation made under the zone system is technically out of compliance with OSHA's existing standard. However, because the NEC represents standard industry practice, existing zone system installations will almost certainly have been installed in accordance with an edition of the NEC that recognizes the zone classification system (the 1999 and 2002 editions). These editions of the NEC explicitly require documentation of hazardous locations. Thus, an employer with an existing installation made under the zone classification system should already have the documentation required by § 1910.307(b). Therefore, OSHA believes that the benefits of having documentation for existing zone-classified installations justify the small burden that would be placed on employers. For these reasons, OSHA is proposing to apply the documentation requirement to all hazardous location installations made under the zone classification system. This will provide employers, employees, and OSHA with information critical for determining which equipment is suitable in a given hazardous location.

Requirements applicable only to installations made after the effective date of the final rule.

Paragraph (b)(4) of proposed § 1910.302 would make the following provisions applicable only to installations made or overhauled

after the effective date of the final rule:

See the discussion of the term “overhaul” later in this section of the preamble.

§ 1910.303(f)(4)—Disconnecting means and circuits—Capable of accepting a lock

§ 1910.303(f)(5)—Disconnecting means and circuits—Marking for series combination ratings

§ 1910.303(g)(1)(iv) and (g)(1)(vii)—600 Volts, nominal, or less—Space about electric equipment

§ 1910.303(h)(5)(vi)—Over 600 volts, nominal—Working space and guarding

§ 1910.304(b)(1)—Branch circuits—Identification of multiwire branch circuits

§ 1910.304(b)(3)—Branch circuits—Identification of ungrounded conductors

§ 1910.304(b)(4)(i)—Branch circuits—Ground-fault circuit interrupter protection for personnel

§ 1910.304(f)(2)(i)(A), (f)(2)(i)(B) (but not the introductory text to § 1910.304(f)(2)(i), and (f)(2)(iv)(A)—Overcurrent protection—Overcurrent protection, feeders and branch circuits for over 600 volts, nominal

§ 1910.305(a)(3)(v)—Wiring methods—Cable trays

§ 1910.305(c)(3)(ii)—Switches—Connection of switches

§ 1910.305(c)(5)—Switches—Grounding

§ 1910.306(a)(1)(ii)—Electric signs and outline lighting—Disconnecting means

§ 1910.306(c)(4)—Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts—Operation

§ 1910.306(c)(5)—Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts—Location

§ 1910.306(c)(6)—Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts—Identification and signs

§ 1910.306(c)(7)—Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts—Single-car and multicar installations

§ 1910.306(j)(1)(iii)—Swimming pools, fountains, and similar installations—Receptacles

§ 1910.306(k)—Carnivals, circuses, fairs, and similar events

§ 1910.308(a)(5)(v) and (a)(5)(vi)(B)—Systems over 600 volts, nominal—Interrupting and isolating devices

§ 1910.308(a)(7)(vi)—Systems over 600 volts, nominal—Tunnel installations

§ 1910.308(b)(3)—Emergency power systems—Signs

§ 1910.308(c)(3)—Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits—Separation from conductors of other circuits

§ 1910.308(f)—Solar photovoltaic systems

These provisions are based on requirements that have been added to the National Electrical Code since the 1978 edition. OSHA has never required employers to comply with these requirements, and the Agency believes that the modest increase in employee protection that would result from compliance with them would not be worth the substantial expense that employers would incur if existing installations had to be retrofitted to conform to those provisions. On the other hand, employers would incur minimal costs to achieve this increase in protection if they only needed to assure that new installations comply with the listed provisions. In local jurisdictions requiring compliance with the NEC, there should be no additional costs involved, because the installations would already conform to the new OSHA requirements. The Agency believes that even in other jurisdictions, the vast majority of installations already

comply with the latest edition of the NEC, because compliance with the latest Code is standard industry practice.

OSHA is considering making the new requirements in revised Subpart S effective 90 days after the final rule is published in the

Federal Register

. The Agency requests comments on whether this provides sufficient time to implement the changes required by the revised standard. It should be noted that applying new provisions only to new installations is the same approach that OSHA took in promulgating the current version of Subpart S in 1981. The Agency found that this approach was successful and has no indication that it was unduly burdensome or insufficiently protective.

There are also many provisions in proposed Subpart S that are not contained in the existing standard but cannot be considered totally “new” provisions. Most of these “new” requirements were actually contained in the 1971 NEC. Table 1 lists these “new” provisions and denotes their counterparts in the 1971 NEC. From March 15, 1972, until April 16, 1981, Subpart S incorporated the 1971 NEC by reference in its entirety. Accordingly, OSHA required employers to comply with every requirement in the 1971 NEC for any new installation made between those dates and for any replacement, modification, repair, or rehabilitation made during that period. The current standard, which became effective on April 16, 1981, omitted many of the detailed provisions of the NEC because they were already addressed by the more general requirements that were contained in the OSHA standard. For example, OSHA did not carry forward 1971 NEC Section 110-11, which required equipment to be suitable for the environment if it is installed where the environment could cause deterioration. However, the requirement for equipment to be suitable for the location in which it was installed is implicit in the more general requirements in existing § 1910.303(a) that equipment be approved and in existing § 1910.303(b)(2) that equipment be installed in accordance with any instructions included in its listing or labeling. (Equipment that is not suitable for installation in deteriorating environments, such as wet or damp locations, will include instructions warning against such installation. These instructions are required by the nationally recognized laboratory listing or labeling the product.)

Even though OSHA has not required employers to maintain their installations in compliance with these older provisions, the Agency believes that employers' installations actually do comply with those requirements. The vast majority of employers are following the entire National Electrical Code applicable to their installations, as noted in the Economic Analysis section of this preamble.

For these reasons, OSHA is not proposing to exempt installations made after March 15, 1972, from meeting any provision listed in Table 1 and is not including any of these provisions in § 1910.302(b)(4) (the list of provisions that apply only to new installations). The Agency invites public comment on whether this approach is reasonable.

All of the requirements in question appear in some version in every edition of the NEC since 1972.

Table 1.—“New” Provisions Contained in 1971 NEC

Proposed provision

Equivalent 1971 NEC section

Subject

§ 1910.303(b)(3)

110-20

Insulation integrity.

(b)(4)

110-9

Interrupting rating.

(b)(5)

110-10

Circuit impedance and other characteristics.

(b)(6)

110-11

Deteriorating agents.

(b)(7)

110-12

Mechanical execution of work.

(b)(8)

110-4(a) and (d)

Mounting and cooling of equipment.

110-12

110-13

(c)(1)

110-14

Electrical connections, general.

§ 1910.304(b)(2)

210-21(b)

Branch circuits, receptacles and cord connectors.

(b)(5)

210-21

Branch circuits, outlet devices.

(b)(6)

210-22

Branch circuits, cord connections.

(e)(1)(iv)

230-70(c)

Services, disconnecting means.

(f)(1)(ix)

110-9

Overcurrent protection, 600 volts, nominal, or less, circuit breaker ratings.

240-11

(f)(2), except for (f)(2)(i)(A), (f)(2)(i)(B), and (f)(2)(iv)(A)

240-5

Overcurrent protection, feeders and branch circuits over 600 volts, nominal.

240-11

240-15

§ 190.305(a)(4)(ii)

320-5

Open wiring on insulators, support.

(b)(1)(iii)

370-7

Conductors entering cabinets, boxes, and fittings, securing conductors.

373-5

(b)(2)(ii)

370-15(b)

Fixture canopy or pan installed in a combustible wall or ceiling.

(e)(1)

373-2

Airspace for enclosures installed in wet or damp locations.

384-5

(h)(3)

710-6

Portable cables, grounding conductors.

(j)(2)(i)

410-52(d)

Receptacles, cord connectors, and attachment plugs; no exposed energized parts.

(j)(2)(iv) through (j)(2)(vii)

410-54

Receptacles installed in wet or damp locations.

(j)(3)(ii)

422-20

Appliances, disconnecting means.

(j)(3)(iii)

422-30(a)

Appliances, nameplates.

(j)(3)(iv)

422-30(b)

Appliances, marking to be visible after installation.

(j)(6)(ii)(A)

110-9

Capacitor switches.

110-10

460-8(c)(4)

(j)(6)(ii)(B)

460-8(c)(1)

Capacitor disconnecting means.

§ 1910.306(c)(3)

620-51(a)

Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts; type of disconnecting means.

(c)(10)

620-72

Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts; motor controllers.

(d)(1)

630-13

Arc welders, disconnecting means.

630-23

(g)(1)(iii)

665-34

Induction and dielectric heating equipment, detachable panels used for access to live parts.

(g)(1)(vi)

665-8

Induction and dielectric heating equipment, ampere rating of disconnecting means.

(j)(4)(iii)

680-20(a)(4)

Swimming pools, fountains, and similar installations, underwater fixtures facing upwards.

§ 1910.308(a)(2)

710-4

Systems over 600 volts, nominal; open installations of braid-covered insulated conductors.

(a)(3)(i)

710-6

Systems over 600 volts, nominal; insulation shielding terminations.

(a)(4)

710-8

Systems over 600 volts, nominal; moisture or mechanical protection for metal-sheathed cables.

(a)(5)(i)

710-21(a)

Systems over 600 volts, nominal; interrupting and isolating devices; guarding and indicating.

(a)(5)(ii)

240-11(a)

Systems over 600 volts, nominal; interrupting and isolating devices; fuses.

710-21(b)

(a)(5)(iii) and (a)(5)(iv)

710-21(b)

Systems over 600 volts, nominal; interrupting and isolating devices; fused cutouts.

(a)(5)(vi), but not (a)(5)(vi)(B)

710-21(c)

Systems over 600 volts, nominal; interrupting and isolating devices; load interrupter switches.

(a)(5)(vii)

710-22

Systems over 600 volts, nominal; interrupting and isolating devices; means for isolating equipment.

(b)(2)

700-14

Emergency systems, emergency illumination.

These provisions have no counterpart in existing Subpart S, but were in the 1971 National Electrical Code.

In addition, OSHA is not including in the list of new provisions in proposed § 1910.302(b)(4) any proposed provision that merely provides an alternative means of compliance for an existing requirement. For example, as noted earlier, § 1910.307(g) provides alternative requirements for installations in hazardous (classified) locations based on the zone classification system rather than the division classification system that is required under the existing standard. Such requirements accept alternative installation techniques recognized as being equally protective by the NEC and NFPA 70E, and there is no need to limit them to new installations.

OSHA also believes that there is no need to grandfather requirements that apply only to temporarily installed equipment and wiring.

The few new requirements applying to temporarily installed equipment and wiring have been in the National Electrical Code since at least 1999 and, in most cases, since before that. Employers should already be in compliance with such requirements since the temporary installations almost certainly were put into place well after 1999. For example, proposed § 1910.304(b)(4)(ii) contains requirements for providing ground-fault circuit interrupter protection for temporary wiring installations that are used during maintenance, remodeling, or repair of buildings, structures, or equipment or during similar activities. Temporary wiring installations used for any of these purposes were likely to have been installed well after 1999. An employer who is complying with the 1999 or later edition of the NEC will already be complying with this provision of the proposal. Even employers who are not complying with recent versions of the NEC for temporary wiring will face only the minimal cost of providing ground-fault circuit interrupters; no changes would need to be made to any existing permanent wiring, which might involve considerably more costs. The Agency requests comments on whether any new requirements applying only to temporarily installed equipment or wiring should also be listed in § 1910.302(b)(4), and why.

For the purposes of this discussion, “temporarily installed equipment or wiring” is wiring and equipment installed on a short-term rather than a long-term or permanent basis. It includes temporary wiring covered by proposed § 1910.305(a)(2) and other equipment and wiring similarly installed on a short-term basis.

Additionally, OSHA recognizes that, in a proposed standard this extensive, some new requirements might have been overlooked and some subtle changes in existing requirements might have unanticipated consequences. Therefore, the Agency requests comments on whether there are any other new or revised requirements in the proposal that should not apply to existing installations.

Requirements applicable only to installations made after April 16, 1981.

Paragraph (b)(3) of § 1910.302 lists requirements that apply only to installations made after April 16, 1981. This proposed paragraph carries forward essentially the same list as is currently in § 1910.302(b)(3). No provisions have been added to or removed from the list.

Requirements applicable only to installations made after March 15, 1972.

Paragraph (b)(2) of existing § 1910.302 requires all installations made after March 15, 1972, and every major replacement, modification, repair, or rehabilitation made after that date to meet all the installation requirements in Subpart S except for those listed in § 1910.302(b)(3) and (b)(4). A note following existing § 1910.302(b)(2) indicates that “major replacements, modifications, repairs, or rehabilitations” include work similar to that involved when a new building or

facility is built, a new wing is added, or an entire floor is renovated.

Paragraph (b)(2) of proposed § 1910.302 would require all installations built or overhauled after March 15, 1972, to comply with all of the requirements of §§ 1910.302 through 1910.308, except as provided in § 1910.302(b)(3) and (b)(4). As discussed earlier, these latter two paragraphs limit the application of newer provisions of Subpart S to installations made during later periods.

In the proposal, OSHA is introducing the term “overhaul” to include the types of activities that would trigger compliance with the otherwise grandfathered provisions of Subpart S for older installations. “Overhaul” is defined as follows:

Overhaul

means to perform a major replacement, modification, repair, or rehabilitation similar to that involved when a new building or facility is built, a new wing is added, or an entire floor is renovated.

Thus, this new term, which is based on language in current Subpart S, incorporates all the elements of “major replacement, modification, or rehabilitation” in the text of existing § 1910.302(b)(2) and in the note following that provision. OSHA believes that the proposed language will simplify the standard without making any substantive change to the way in which Subpart S applies to older installations.

C. Summary of Changes in §§ 1910.303 Through 1910.308

The Distribution Table for Subpart S lists all the provisions and sections from §§ 1910.303 through 1910.308 of the electrical standard. This table summarizes any proposed changes being made to the standard that involve grammatical edits, additions, removals, and paragraph numbers. There are places in the standard where no substantial change is made. Most of the changes are editorial in nature. Some of the requirements would be removed because the material is considered outdated. However, the substantive changes to be made to the standard will be discussed in further detail following this section.

Distribution Table

OLD—section

NEW—section

Description of changes and rationale

See the note at the end of the table

§ 1910.303 General

1910.303(a)

No substantive change. A reference to the § 1910.399 definition of “approved” is added for clarification.

1910.303(b)(1), introductory text

No substantive change.

1910.303(b)(1)(i)

No substantive change.

1910.303(b)(1)(ii)

No substantive change.

1910.303(b)(1)(iii)

**Adds wire-bending and connection space to the list of things to consider when judging equipment.

1910.303(b)(1)(iii)

1910.303(b)(1)(iv)

No substantive change.

1910.303(b)(1)(iv)

1910.303(b)(1)(v)

No substantive change.

1910.303(b)(1)(v)

1910.303(b)(1)(vi)

No substantive change.

1910.303(b)(1)(vi)

1910.303(b)(1)(vii)

No substantive change.

1910.303(b)(1)(vii)

1910.303(b)(1)(viii)

No substantive change.

1910.303(b)(2)

No substantive change.

1910.303(b)(3)

**Adds a requirement for completed wiring to be free from short circuits and grounds other than those required in the standard.

1910.303(b)(4)

**Adds requirements for equipment intended to interrupt current to have adequate interrupting ratings.

1910.303(b)(5)

**Adds requirements for the coordination of overcurrent protection for circuits and equipment.

1910.303(b)(6)

**Adds a requirement for conductors and equipment to be identified for the purpose when installed in an environment containing deteriorating agents.

1910.303(b)(7)

**Adds requirements for installing electric equipment in a neat and workmanlike manner.

1910.303(b)(8)

**Adds requirements for equipment to be mounted securely and to allow for proper cooling.

1910.303(c)(1)

**Adds requirements to ensure that electrical connections are secure and electrically safe.

1910.303(c)(2)(i)

**Adds requirements for connections at terminals.

1910.303(c)(2)(ii)

**Adds requirements for the identification of terminals intended for connection to more than one conductor or to aluminum.

1910.303(c)

1910.303(c)(3)(i)

No substantive change.

1910.303(c)(3)(ii)

**Adds a requirement that wire connectors or splicing means installed on directly buried conductors be listed for such use.

1910.303(d)

No substantive change.

1910.303(e)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.303(f)

1910.303(f)(1)

1910.303(f)(2)

1910.303(f)(3)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.303(f)(4)

Adds a requirement for disconnecting means required by Subpart S to be capable of accepting a lock. This provision is added to make the Subpart S requirements on disconnecting means consistent with § 1910.147(c)(2)(iii), which requires energy isolating devices (a generic term, which includes electrical disconnecting means) to be designed to accept a lockout device.

1910.303(f)(5)

**Adds marking requirements for series combination ratings of circuit breakers or fuses.

1910.303(g)(1), introductory text

No substantive change.

1910.303(g)(1)(i)

Table S-1, Note 3

**The proposal revises the language to clarify how wide and high the clear space must be.

1910.303(g)(1)(ii)

No substantive change.

1910.303(g)(1)(iii)

No substantive change.

1910.303(g)(1)(iv)

**Adds a requirement for a second entrance on equipment rated 1200 amperes under certain conditions.

1910.303(g)(1)(iv)

1910.303(g)(1)(i)(B)

**Reduced the minimum width of the clear space to 762 mm.

1910.303(g)(1)(v)

**Adds a prohibition against controlling illumination for working spaces by automatic means only.

1910.303(g)(1)(vi)

**Increased the minimum height of the working space from 1.91m to 1.98m for new installations.

1910.303(g)(1)(vii)

** Adds requirements for switchboards, panelboards, and distribution boards installed for the control of light and power circuits, and motor control centers to be installed in dedicated space and to be protected against damage.

1910.303(g)(2)(i)

No substantive change.

1910.303(g)(2)(ii)

No substantive change.

1910.303(g)(2)(iii)

No substantive change.

1910.303(h)(1)

No substantive change.

1910.303(h)(2), introductory text

1910.303(h)(2)(i)

1910.303(h)(2)(ii)

**The minimum height of fences restricting access to electrical installations over 600 V is reduced from 2.44 m to 2.13 m.

1910.303(h)(2)(i)

1910.303(h)(2)(ii)

1910.303(h)(2)(iii)

1910.303(h)(2)(iv)

1910.303(h)(2)(v)

1910.303(h)(5)(iii)

**1. The proposal organizes these requirements on the basis of whether the installations are indoors or outdoors. (The existing standard organizes them on the basis of whether or not the installations are accessible to unqualified employees.)

2. Adds requirements intended to prevent tampering by the general public.

3. Removes requirement to lock underground box covers weighing more than 45.4 kg.

1910.303(h)(3), introductory text

1910.303(h)(3)

No substantive change.

1910.303(h)(3)(i)

1910.303(h)(5)(i)

Table S-2, Note 3

**The distances in Table S-2 for the depth of working space in front of electric equipment are increased for new installations to match the distances in NFPA 70E-2000.

1910.303(h)(3)(ii)

1910.303(h)(5)(iv)

No substantive change.

1910.303(h)(3)(iii)

1910.303(h)(5)(v)

**The distances in Table S-3 for the elevations of unguarded live parts are increased for new installations to match the distances in NFPA 70E-2000.

1910.303(h)(4)(i)

**The existing standard requires a second entrance to give access to the working space about switchboards and control panels over 600 V if the equipment exceed 1.22 m in width if it is practical to install a second entrance. The proposal requires an entrance on each end of switchboards and panelboards exceeding 1.83 m unless the working space permits a continuous and unobstructed way of travel or the working space is doubled. In addition, the proposal requires the lone entrance permitted under either of these exceptions to be at least the distance specified in Table S-2 from exposed live parts.

1910.303(h)(4)(ii)

No substantive change.

1910.303(h)(5)(ii)

**Adds requirements for equipment operating at 600 V or less installed in rooms or enclosures containing exposed live parts or exposed wiring operating at more than 600 V.

1910.303(h)(5)(vi)

**Adds requirements limiting the installation of pipes or ducts that are foreign to electrical installation operating at more than 600 V.

§ 1910.304 Wiring design and protection

§ 1910.304 Wiring design and protection.

1910.304(a)(1)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.304(a)(2)

No substantive change.

1910.304(a)(3)

No substantive change.

1910.304(b)(1)

**Adds requirements for the identification of multiwire branch circuits.

1910.304(b)(2)(i)

**Adds requirements that receptacles installed on 15- and 20-ampere circuits be of the grounding type and that grounding-type receptacles be installed in circuits within their rating.

1910.304(b)(2)(ii)

**Adds a requirement for grounding contacts on receptacles to be effectively grounded.

1910.304(b)(2)(iii)

**Adds requirements on the methods used to ground receptacles and cord connectors.

1910.304(b)(2)(iv)

**Adds requirements on the replacement of receptacles.

1910.304(b)(2)(v)

**Adds a requirement that receptacles installed on branch circuits having different voltages, frequencies, or types of current be noninterchangeable.

1910.304(b)(3)

**Adds requirements on identification of ungrounded conductors on different systems.

1910.304(b)(4)

**Adds requirements for ground fault circuit interrupter protection.

1910.304(b)(2)

1910.304(b)(5), introductory text

No significant change.

1910.304(b)(5)(i)

**Adds requirements for ratings of lampholders.

1910.304(b)(5)(ii)

**Adds requirements for ratings of receptacles.

1910.304(b)(6)

**Adds requirements for receptacles to be installed wherever cords with attachment plugs are used.

1910.304(c), introductory text

No significant change. (The requirements in existing paragraph (c)(5) are placed in a separate paragraph (d).)

1910.304(c)(1)

**Adds a requirement for the separation of conductors on poles.

1910.304(c)(2)

Increases the minimum clearances for new installations of open conductors and service drops to match those in NFPA 70E-2000.

1910.304(c)(3)

1910.304(c)(3)(i)

No substantive change. (The proposal clarifies that paragraph (c)(2) applies to platforms, projections, or surfaces from which runs of open conductors can be reached.)

1910.304(c)(3)(ii)

**Adds restrictions for installing overhead service conductors near building openings through which materials may be moved.

1910.304(c)(4)

**Adds an exception to the minimum clearance requirement for conductors attached to the side of a building. (The proposal also clarifies that paragraph (c)(2) applies to roof surfaces that are subject to pedestrian or vehicular traffic.)

1910.304(c)(5)

1910.304(d)

No substantive change.

1910.304(d)(1)(i)

1910.304(e)(1)(i)

No substantive change.

1910.304(d)(1)(ii)

1910.304(e)(1)(ii)

No substantive change.

1910.304(e)(1)(iii)

**Adds a requirement for service disconnecting means to be suitable for the prevailing conditions.

1910.304(d)(2)

1910.304(e)(2)

No substantive change.

1910.304(e)(1), introductory text

1910.304(f)(1), introductory text

No substantive change.

1910.304(e)(1)(i)

1910.304(f)(1)(i)

No substantive change.

1910.304(e)(1)(ii)

1910.304(f)(1)(ii)

No substantive change.

1910.304(e)(1)(iii)

1910.304(f)(1)(iii)

**The types of circuits that are allowed to have a single switch disconnect for multiple fuses are now specified in the standard.

1910.304(e)(1)(iv)

1910.304(f)(1)(iv)

No substantive change.

1910.304(e)(1)(v)

1910.304(f)(1)(v)

**Adds a requirement to clarify that handles of circuit breakers and similar moving parts also need to be guarded so that they do not injure employees.

1910.304(e)(1)(vi)(A)

1910.304(f)(1)(vi)

No substantive change.

1910.304(e)(1)(vi)(B)

1910.304(f)(1)(vii)

No substantive change.

1910.304(e)(1)(vi)(C)

1910.304(f)(1)(viii)

**Adds circuit breakers used on 277-volt fluorescent lighting circuits to the types of breakers required to be marked “SWD.”

1910.304(f)(1)(ix)

**Adds a requirement to clarify ratings of circuit breakers.

1910.304(e)(2)

1910.304(f)(2)

**Adds specific requirements on how to protect feeders and branch circuits energized at more than 600 volts.

1910.304(f), introductory text

1910.304(g), introductory text

No substantive change.

1910.304(f)(1), introductory text

1910.304(g)(1), introductory text

No substantive change.

1910.304(f)(1)(i)

1910.304(g)(1)(i)

No substantive change.

1910.304(f)(1)(ii)

1910.304(g)(1)(ii)

No substantive change.

1910.304(f)(1)(iii)

1910.304(g)(1)(iii)

No substantive change.

1910.304(f)(1)(iv)

1910.304(g)(1)(iv)

No substantive change. (The specific voltage ratings in existing paragraphs (g)(1)(iv)(B) and (g)(1)(iv)(C) are being removed. However, this is not a substantive change as those are the voltages used in the described systems.)

1910.304(f)(1)(v)

1910.304(g)(1)(v)

**Adds an exception to the requirement to ground systems for high-impedance grounded systems of 480 V to 1000 V under certain conditions.

1910.304(f)(2)

**Removed. The hazard is addressed in proposed § 1910.304(a)(1)(i), which requires conductors used as grounded conductors to be identifiable and distinguishable from other conductors.

1910.304(g)(2)

**Relaxes requirements for grounding portable and vehicle mounted generators so that the requirements match those in OSHA's Construction Standards (§ 1926.404(f)(3)).

1910.304(f)(3)

1910.304(g)(3)

No substantive change.

1910.304(f)(4)

1910.304(g)(4)

No substantive change.

1910.304(f)(5)(i)

1910.304(g)(5)(i)

No substantive change.

1910.304(f)(5)(ii)

1910.304(g)(5)(ii)

No substantive change.

1910.304(f)(5)(iii)

1910.304(g)(5)(iii)

No substantive change.

1910.304(f)(5)(iv)

1910.304(g)(5)(iv)

1910.304(g)(5)(v)

**The exceptions for grounding fixed equipment operating at more than 150 V are extended to all fixed electric equipment regardless of voltage. Also, the proposal includes a new exception for double-insulated equipment.

1910.304(f)(5)(v)

1910.304(g)(5)(vi)

1910.304(g)(5)(vii)

**Adds the following equipment to the list of cord- and plug-connected equipment required to be grounded: stationary and fixed motor-operated tools and light industrial motor-operated tools.

1910.304(f)(5)(vi)

1910.304(g)(6)

**Adds frames and tracks of electrically operated hoists to the list of nonelectrical equipment required to be grounded.

1910.304(f)(6)

1910.304(g)(7)

No substantive change.

1910.304(f)(7)(i)

1910.304(g)(8), introductory text

No substantive change.

1910.304(f)(7)(ii)

1910.304(g)(8)(i)

No substantive change.

1910.304(f)(7)(iii)

1910.304(g)(8)(ii)

No substantive change.

§ 1910.305 Wiring methods, components, and equipment for general use

1910.305(a), introductory text

No substantive change.

1910.305(a)(1)(i)

**Adds a requirement that equipment be bonded so as to provide adequate fault-current-carrying capability. Also, clarifies that nonconductive coatings need to be removed unless the fittings make this unnecessary.

1910.305(a)(1)(ii)

**Adds an exception to the bonding requirement for the reduction of electrical noise.

1910.305(a)(1)(ii)

1910.305(a)(1)(iii)

No substantive change.

1910.305(a)(2), introductory text

No substantive change. Removes the provision allowing temporary wiring to be of a class less than permanent wiring per the 2002 NEC. The change has no substantive effect because temporary wiring is required to meet the same requirements regardless of the deleted language. (Both the proposal and the existing standard contain the following requirement: “Except as specifically modified in this paragraph, all other requirements of this subpart for permanent wiring shall apply to temporary wiring installations.”)

1910.305(a)(2)(i), introductory text

No substantive change.

1910.305(a)(2)(i)(A)

Removes demolition from the list of activities for which temporary wiring is permitted . Demolition is one form of construction work, which is not covered by the Subpart S installation requirements.

1910.305(a)(2)(i)(B)

1910.305(a)(2)(i)(C)

**Adds emergencies to the list of activities for which temporary wiring is permitted.

1910.305(a)(2)(i)(C)

1910.305(a)(2)(i)(B)

No substantive change.

1910.305(a)(2)(ii)

**Clarifies that temporary wiring must be removed when the project or purpose for which it was used has been completed.

1910.305(a)(2)(ii)

1910.305(a)(2)(iii)

No substantive change.

1910.305(a)(2)(iii)(A)

1910.305(a)(2)(iv)

**Feeders may now only be run as single insulated conductors when accessible to qualified employees only and used for experiments, development work, or emergencies. (Individual requirements are placed in separate paragraphs.)

1910.305(a)(2)(iii)(B)

1910.305(a)(2)(v)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.305(a)(2)(iii)(C)

1910.305(a)(2)(vi)

No substantive change.

1910.305(a)(2)(iii)(D)

1910.305(a)(2)(vii)

No substantive change.

1910.305(a)(2)(iii)(E)

1910.305(a)(2)(viii)

**Adds a requirement that disconnecting means for a multiwire circuit simultaneously disconnect all ungrounded conductors of the circuit.

1910.305(a)(2)(iii)(F)

1910.305(a)(2)(ix)

**This provision no longer allows installing fixtures or lampholders more than 2.1 meters above the working surface as a means of guarding. Also, the proposal adds a requirement for grounding metal-case sockets.

1910.305(a)(2)(iii)(G)

1910.305(a)(2)(x)

No substantive change.

1910.305(a)(2)(xi)

**Adds requirements for cable assemblies and flexible cords and cables to be adequately supported.

1910.305(a)(3)(i)(A)

1910.305(a)(3)(i)

No substantive change.

1910.305(a)(3)(i)(B)

1910.305(a)(3)(ii)

**Adds several types of cables and single insulated conductors to the list of types permitted in industrial establishments.

1910.305(a)(3)(iii)

**Adds a requirement limiting the use of metallic cable trays as an equipment grounding conductor.

1910.305(a)(3)(i)(C)

1910.305(a)(3)(iv)

No substantive change.

1910.305(a)(3)(v)

**Adds a requirement limiting the use of nonmetallic cable trays.

1910.305(a)(3)(ii)

1910.305(a)(3)(vi)

No substantive change.

1910.305(a)(4)(i)

No substantive change.

1910.305(a)(4)(ii)

**Adds specific support requirements for conductors smaller than No. 8.

1910.305(a)(4)(iii)

No substantive change.

1910.305(a)(4)(iv)

No substantive change.

1910.305(a)(4)(v)

No substantive change.

1910.305(b)(1)

1910.305(b)(1)(i)

1910.305(b)(1)(ii)

1910.305(b)(1)(iii)

No substantive change. (Individual requirements are placed in separate paragraphs.)

**Adds requirements for supporting cables entering cabinets, cutout boxes, and meter sockets.

1910.305(b)(2)

1910.305(b)(2)(i)

No substantive change.

1910.305(b)(2)(ii)

**Adds a requirement for any exposed edge of a combustible ceiling finish at a fixture canopy or pan to be covered with noncombustible material.

1910.305(b)(3)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.305(c)(1)

1910.305(c)(2)

1910.305(c)(3)(i)

No substantive change.

1910.305(c)(3)(ii)

**Adds a requirement for load terminals on switches to be deenergized when the switches are open except under limited circumstances.

1910.305(c)(4)

**Adds a specific requirement for flush-mounted switches to have faceplates that completely cover the opening and that seat against the finished surface.

1910.305(c)(2)

1910.305(c)(5)

**Adds a requirement to ground faceplates for snap switches.

1910.305(d)

1910.305(d)(1)

1910.305(d)(2)

1910.305(d)(3)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.305(e)(1)

**Adds a requirement for metallic cabinets, cutout boxes, fittings, boxes, and panelboard enclosures installed in damp or wet locations to have an air space between the enclosure and the mounting surface.

1910.305(e)(2)

No substantive change.

1910.305(f)

1910.305(f)(1)

1910.305(f)(2)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.305(g)(1)(i)

1910.305(g)(1)(ii)

**Adds the following to the types of connections permitted for flexible cords and cables: portable and mobile signs and connection of moving parts. The proposal also clarifies that flexible cords and cables may be used for temporary wiring as permitted in § 1910.305(a)(2).

1910.305(g)(1)(ii)

1910.305(g)(1)(iii)

No substantive change.

1910.305(g)(1)(iii)

1910.305(g)(1)(iv)

No substantive change. (Clarifies that flexible cords and cables may not be installed inside raceways.)

1910.305(g)(1)(iv)

1910.305(g)(1)(v)

**Permits additional cord types to be used in show windows and show cases.

1910.305(g)(2)(i)

**Adds new types of cords to the list of those that must be marked with their type designation.

1910.305(g)(2)(ii)

**Changed the minimum size of hard service and junior hard service cords that may be spliced from No. 12 to 14.

1910.305(g)(2)(iii)

No substantive change.

1910.305(h)

1910.305(h)(1)

1910.305(h)(2)

1910.305(h)(3)

1910.305(h)(6)

1910.305(h)(7)

1910.305(h)(8)

**Permits the minimum size of the insulated ground-check conductor of Type G-GC cables to be No. 10 rather than No. 8.

1910.305(h)(4)

**Adds a requirement for shields to be grounded.

1910.305(h)(5)

**Adds minimum bending radii requirements for portable cables.

1910..305(i)(1)

1910.305(i)(1)

No substantive change.

1910.305(i)(2)

No substantive change.

1910.305(i)(3)

**Also permits fixture wire to be used in fire alarm circuits.

1910.305(j)(1)(i)

No substantive change.

1910.305(j)(1)(ii)

No substantive change. (Clarifies that metal-shell paper-lined lampholders may not be used for handlamps.)

1910.305(j)(1)(iii)

**Adds a requirement that the grounded circuit conductor, where present, be connected to the screw shell.

1910.305(j)(1)(iv)

No substantive change.

1910.305(j)(2)(i)

**Adds requirements to ensure that attachment plugs and connectors have no exposed live parts.

1910.305(j)(2)(i)

1910.305(j)(2)(ii)

No substantive change.

1910.305(j)(2)(iii)

**Clarifies that nongrounding-type receptacles may not be used with grounding-type attachment plugs.

1910.305(j)(2)(ii)

1910.305(j)(2)(iv)

No substantive change.

1910.305(j)(2)(v)

1910.305(j)(2)(vi)

1910.305(j)(2)(vii)

**Adds requirements for receptacles outdoors to be installed in weatherproof enclosures appropriate for the use of the receptacle and for the location.

1910.305(j)(3)(i)

No substantive change.

1910.305(j)(3)(ii)

**Adds a requirement to group and identify disconnecting means for appliances supplied by more than one source.

1910.305(j)(3)(iii)

**Adds requirements for marking frequency and required external overload protection for appliances.

1910.305(j)(3)(iv)

**Clarifies that markings must be visible or easily accessible after installation.

1910.305(j)(4)

No substantive change.

1910.305(j)(4)(i)

No substantive change.

1910.305(j)(4)(ii)(A)

1910.305(j)(4)(ii)

No substantive change.

1910.305(j)(4)(ii)(B)

1910.305(j)(4)(iii)

No substantive change.

1910.305(j)(4)(ii)(C)

Removed. All disconnecting means must be capable of being locked in the open position by §§ 1910.302(c) and 1910.303(f)(4).

1910.305(j)(4)(ii)(D)

1910.305(j)(4)(iv)

No substantive change.

1910.305(j)(4)(ii)(E)

1910.305(j)(4)(v)

No substantive change.

1910.305(j)(4)(ii)(F)

1910.305(j)(4)(vi)

No substantive change.

1910.305(j)(4)(iii)

1910.305(j)(4)(vii)

No substantive change.

1910.305(j)(4)(iv)(A)

Removed. Covered by § 1910.303(g)(2), (h)(2), and (h)(5).

1910.305(j)(4)(iv)(B)

1910.305(j)(4)(viii)

No substantive change.

1910.305(j)(5)(i)

No substantive change.

1910.305(j)(5)(ii)

No substantive change.

1910.305(j)(5)(iii)

No substantive change.

1910.305(j)(5)(i)(iv)

No substantive change. (Oil-insulated transformers installed indoors are presumed to present a hazard to employees, and lack of employee exposure to a hazard is an affirmative defense.)

1910.305(j)(5)(i)(v)

No substantive change.

1910.305(j)(5)(i)(vi)

No substantive change.

1910.305(j)(5)(i)(vii)

No substantive change.

1910.305(j)(5)(i)(viii)

No substantive change.

1910.305(j)(6)(i)

No substantive change.

1910.305(j)(6)(ii), introductory text

No substantive change.

1910.305(j)(6)(ii)(A)

1910.305(j)(6)(ii)(B)

**Adds requirements to provide disconnecting means of adequate capacity for capacitors operating at more than 600 V.

1910.305(j)(6)(ii)(A)

*1910.305(j)(6)(ii)(C)

No substantive change.

1910.305(j)(6)(ii)(B)

1910.305(j)(6)(ii)(D)

No substantive change.

1910.305(j)(7)

No substantive change.

§ 1910.306 Specific purpose equipment and installations.

1910.306(a)(1)

1910.306(a)(1)(i)

1910.306(a)(2)(i)

1910.306(a)(2)(ii)

**Reorganized and clarified the requirements for disconnecting means for signs. The proposal does not apply these requirements to exit signs.

1910.306(a)(2)

1910.306(a)(2)(iii)

No substantive change.

1910.306(b), introductory text

No substantive change.

1910.306(b)(1)(i)

1910.306(b)(1)

**Adds specific requirements for the type and location of disconnecting means for runway conductors.

1910.306(b)(1)(ii)

1910.306(b)(2)

No substantive change. (The requirements are being reorganized.)

1910.306(b)(2)

1910.306(b)(3)

No substantive change.

1910.306(b)(3)

1910.306(b)(4)

No substantive change.

1910.306(c)

1910.306(c), introductory text

**This paragraph now covers wheelchair lifts, and stairway chair lifts.

1910.306(c)(1)

No substantive change.

1910.306(c)(2)

1910.306(c)(8)

No substantive change.

1910.306(c)(3)

1910.306(c)(2)

No substantive change.

1910.306(c)(3)

**Adds requirements for the type of disconnecting means.

11910.306(c)(4)

**Adds requirements for the operation of disconnecting means.

1910.306(c)(5)

**Adds requirements for the location of disconnecting means.

1910.306(c)(6)

**Adds requirements for the identification of disconnecting means.

1910.306(c)(7)

**Adds requirements for disconnecting means for single car and multicar installations supplied by more than one source.

1910.306(c)(9)

**Adds requirements for warning signs for interconnected multicar controllers.

1910.306(c)(10)

**Adds exceptions related to the location of motor controllers.

1910.306(d)(1)

**Adds requirements for the type and rating of the disconnecting means.

1910.306(d)(2)

Clarifies that a supply circuit switch may be used as a disconnecting means if the circuit supplies only one welder.

1910.306(e)

**Adds a requirement to group the disconnecting means for the HVAC systems serving information technology rooms with the disconnecting means for the information technology equipment. (The existing standard refers to this equipment as data processing equipment.)

1910.306(f), introductory text

**Adds coverage of X-rays for dental or medical use.

1910.306(f)(1)(i)

No substantive change.

1910.306(f)(1)(ii)

No substantive change.

1910.306(f)(2)(i)

No substantive change.

1910.306(f)(2)(ii)

No substantive change.

1910.306(g)(1)

1910.306(g), introductory text

No substantive change.

1910.306(g)(2)(i)

1910.306(g)(1)(i)

No substantive change.

1910.306(g)(2)(ii)

1910.306(g)(1)(ii)

No substantive change.

1910.306(g)(2)(iii)

1910.306(g)(1)(iii)

**Adds a requirement for the installation of doors or detachable panels to provide access to internal parts. Adds a requirement that detachable panels not be readily removable.

1910.306(g)(2)(iv)

1910.306(g)(1)(iv)

No substantive change.

1910.306(g)(2)(v)

1910.306(g)(1)(v)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.306(g)(2)(vi)

1910.306(g)(1)(vi)

**Adds a requirement to ensure adequate rating of disconnecting means. The proposal also clarifies when the supply circuit disconnecting means may be used as the disconnecting means for induction and dielectric heating equipment.

1910.306(g)(3)

1910.306(g)(2)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.306(h)(1)

1910.306(h), introductory text

No substantive change.

1910.306(h)(2)

1910.306(h)(1)

No substantive change.

1910.306(h)(3)

1910.306(h)(2)

No substantive change.

1910.306(h)(4)(i)

1910.306(h)(4)(ii)

1910.306(h)(3)

No substantive change. (The two provisions are combined into one paragraph.)

1910.306(h)(5)(i)

1910.306(h)(4)(i)

No substantive change.

1910.306(h)(5)(ii)

1910.306(h)(4)(ii)

No substantive change.

1910.306(h)(6)(i)

1910.306(h)(5)(i)

**Adds requirements limiting primary and secondary voltage on isolating transformers supplying receptacles for ungrounded cord- and plug-connected equipment. Also, adds requirement for overcurrent protection for circuits supplied by these transformers.

1910.306(h)(6)(ii)

1910.306(h)(5)(ii)

No substantive change.

1910.306(h)(6)(iii)

1910.306(h)(5)(iii)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.306(h)(7)(i)

1910.306(h)(7)(ii)

1910.306(h)(6)(i)

No substantive change.

1910.306(h)(7)(iii)

1910.306(h)(6)(ii)

No substantive change.

1910.306(h)(7)(iv)

1910.306(h)(6)(iii)

No substantive change.

1910.306(h)(8)

1910.306(h)(7)

No substantive change.

1910.306(h)(9)(i)

1910.306(h)(8)(i)

No substantive change.

1910.306(h)(9)(ii)

1910.306(h)(8)(ii)

No substantive change.

1910.306(i)(1)

No substantive change.

1910.306(i)(2)

**Allows the disconnecting means for a center pivot irrigation machine to be located not more than 15.2 m (50 ft) from the machine if the disconnecting means is visible from the machine. (Individual requirements are placed in separate paragraphs.)

1910.306(j)(1)

1910.306(j), introductory text

**Clarifies that hydro-massage bathtubs are covered by this paragraph.

1910.306(j)(2)(i)

1910.306(j)(1)(i)

No substantive change.

1910.306(j)(1)(ii)

**Extends the boundary within which receptacles require GFCI protection from 4.57 m (15 ft) to 6.08 m (20 ft) for new installations.

1910.306(j)(1)(iii)

**Adds requirements for the installation of at least one receptacle near permanently installed pools at dwelling units.

1910.306(j)(2)(ii)(A)

1910.306(j)(2)(i)

**Clarifies that ceiling suspended (paddle) fans are covered by this requirement.

1910.306(j)(2)(ii)(B)

1910.306(j)(2)(ii)

No substantive change.

1910.306(j)(3)

No substantive change.

1910.306(j)(4)(i)

No substantive change.

1910.306(j)(4)(ii)

No substantive change.

1910.306(j)(4)(iii)

**Adds a requirement to guard lighting fixtures facing upward.

1910.306(j)(5)

No substantive change.

1910.306(k)

**Adds requirements for carnivals, circuses, fairs, and similar events.

§ 1910.307 Hazardous (classified) locations.

§ 1910.307(a)

1910.307(a)

**Adds the Zone classification system for Class I locations. (See detailed discussion later in this section of the preamble.)

1910.307(b)

**Adds documentation requirements for hazardous locations classified using either the division or zone classification system.

1910.307(b), introductory text

1910.307(c), introductory text

No substantive change.

1910.307(b)(1)

1910.307(c)(1)

No substantive change.

1910.307(b)(2)(i)

1910.307(c)(2)(i)

No substantive change.

1910.307(b)(2)(i)(ii), introductory text

1910.307(c)(2)(ii), introductory text

No substantive change.

1910.307(b)(2)(ii)(A)

1910.307(c)(2)(ii)(A)

No substantive change.

1910.307(b)(2)(ii)(B)

1910.307(c)(2)(ii)(B)

**Also permits fixtures approved for Class II, Division 2 locations to omit the group marking.

1910.307(b)(2)(ii)(C)

1910.307(c)(2)(ii)(C)

No substantive change.

1910.307(b)(2)(ii)(D)

1910.307(c)(2)(ii)(D)

No substantive change.

1910.307(c)(2)(ii)(E)

**Adds a requirement that electric equipment suitable for an ambient temperature exceeding 40EC (104EF) be marked with the maximum ambient temperature.

1910.307(b)(3)

1910.307(c)(3)

No substantive change.

1910.307(b)(3), Note

1910.307(c)(3), Note

The last sentence of the note is removed to make it clear that the OSHA standard does not incorporate the National Electrical Code by reference. The NEC continues to be a guideline that employers may follow in determining the type and design of equipment and installations that will meet the OSHA standard.

1910.307(c)

1910.307(d)

No substantive change.

1910.307(d)

1910.307(e)

No substantive change.

1910.307(f)

**The proposal lists the specific protective techniques for electrical installations in hazardous locations classified under the division classification system.

1910.307(g)

**Adds the zone classification system as an alternative method of installing electric equipment in hazardous locations. This paragraph sets the protective techniques and other requirements necessary for safe installation of electric equipment in hazardous locations classified under the zone classification system. (See detailed discussion later in this section of the preamble.)

§ 1910.308 Special systems

1910.308(a), introductory text

No substantive change.

1910.308(a)(1)(i)

1910.308(a)(3)(ii)

**Adds the following wiring methods to those acceptable for installations operating at more than 600 V: electrical metallic tubing, rigid nonmetallic conduit, busways, and cable bus. The proposal also removes the specific requirement to support cables having a bare lead sheath or a braided outer covering in a manner to prevent damage to the braid or sheath. This hazard is covered by § 1910.303(b)(1) and (b)(8)(i) and new § 1910.308(a)(4).

1910.308(a)(1)(ii)

No substantive change.

1910.308(a)(2)

1910.308(a)(3)(i)

**Adds requirements to ensure that high-voltage cables can adequately handle the voltage stresses placed upon them and to ensure that any coverings are flame retardant.

1910.308(a)(4)

**Adds requirements for the protection of high-voltage cables against moisture and physical damage where the cable conductors emerge from a metal sheath.

1910.308(a)(2)(i)

1910.308(a)(5)(i)

No substantive change.

1910.308(a)(5)(ii)

**Adds requirements for fuses to protect each ungrounded conductor, for adequate ratings of fuses installed in parallel, and for the protection of employees from power fuses of the vented type.

1910.308(a)(2)(ii)

1910.308(a)(5)(iii)

**Clarifies that distribution cutouts are not suitable for installation in buildings or transformer vaults.

1910.308(a)(5)(iv)

**Adds requirements for fused cutouts to either be capable of interrupting load current or be supplemented by a means of interrupting load current. In addition, a warning sign would be required for fused cutouts that cannot interrupt load current.

1910.308(a)(5)(v)

**Adds a requirement for guarding nonshielded cables and energized parts of oil-filled cutouts.

1910.308(a)(5)(vi)

**Adds requirements to ensure that load interrupting switches will be protected against interrupting fault current and to provide for warning signs for backfed switches.

1910.308(a)(2)(iii)

1910.308(a)(5)(vii)

No substantive change.

1910.308(a)(3)(i)

1910.308(a)(6)(i)

No substantive change.

1910.308(a)(3)(ii)

1910.308(a)(6)(ii)

No substantive change.

1910.308(a)(4)(i)

1910.308(a)(7), introductory text.

No substantive change.

1910.308(a)(4)(ii)

1910.308(a)(7)(i)

1910.308(a)(7)(iii)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.308(a)(7)(ii)

**Clarifies that multiconductor portable cable may supply mobile equipment.

1910.308(a)(4)(iii)

1910.308(a)(7)(iv)

1910.308(a)(7)(v)

No substantive change. (Individual requirements are placed in separate paragraphs.)

1910.308(a)(7)(vi)

**Limits the conditions under which switch or contactor enclosures may be used as junction boxes or raceways.

1910.308(a)(4)(iv)

1910.308(a)(7)(vii)

No substantive change.

1910.308(a)(4)(v)

1910.308(a)(7)(viii)

No substantive change.

1910.308(b)(1)

1910.308(b), introductory text

No substantive change.

1910.308(b)(2)

1910.308(b)(1)

No substantive change.

1910.308(b)(3)

1910.308(b)(2)

**Clarifies that emergency illumination includes all required means of egress lighting, illuminated exit signs, and all other lights necessary to provide required illumination.

1910.308(b)(3)

**Adds requirements to provide signs indicating the presence and location of on-site emergency power sources under certain conditions.

1910.308(c)(1), introductory text

No substantive change.

1910.308(c)(1)(i)

1910.308(c)(1)(ii)

1910.308(c)(1)(iii)

1910.308(c)(1)(i)

1910.308(c)(1)(ii)

1910.308(c)(1)(iii)

**Clarifies the definitions of Class 1, 2, and 3 remote control, signaling, and power-limited circuits based on equipment listing.

1910.308(c)(2)

No substantive change.

1910.308(c)(3)

**Adds requirements for the separation of cables and conductors of Class 2 and Class 3 circuits from cables and conductors of other types of circuits.

1910.308(d)(1)

No substantive change.

1910.308(d)(2), introductory text

No substantive change.

1910.308(d)(2)(i)

No substantive change.

1910.308(d)(2)(ii)

**Adds a requirement for power-limited fire alarm circuit power sources to be listed and marked as such.

1910.308(d)(3)

1910.308(d)(3)(i)

No substantive change.

1910.308(d)(4)

1910.308(d)(3)(ii)

1910.308(d)(3)(iii)

1910.308(d)(3)(iv)

**Clarifies the requirements for installing power-limited fire-protective signaling circuits with other types of circuits. (Individual requirements are placed in separate paragraphs.)

1910.308(d)(5)

1910.308(d)(4)

No substantive change.

1910.308(e)(1)

1910.308(e), introductory text

No substantive change.

1910.308(e)(2)

1910.308(e)(1)

**Clarifies the requirement for listed primary protectors to make it clear that circuits confined within a block do not need protectors.

1910.308(e)(3)(i)

1910.308(e)(2)(i)

1910.308(e)(2)(ii)

No substantive change.

1910.308(e)(3)(ii)

1910.308(e)(2)(iii)

No substantive change.

1910.308(e)(3)(iii)

1910.308(e)(2)(iv)

No substantive change.

1910.308(e)(4)

1910.308(e)(3)

No substantive change.

1910.308(e)(5)(i)

1910.308(e)(4)(i)

No substantive change.

1910.308(e)(5)(ii)

1910.308(e)(4)(ii)

No substantive change.

1910.308(e)(5)(iii)

1910.308(e)(4)(iii)

No substantive change.

1910.308(f)

**Adds requirements to separate conductors of solar photovoltaic systems from conductors of other systems and to provide a disconnecting means for solar photovoltaic systems.

1910.308(g)

**Adds an exception to the provisions on the location of overcurrent protective devices for integrated electrical systems.

Note to table:

**These new and revised provisions are included in the 2000 edition of NFPA 70E standard. The NFPA 70E Committee believes that these provisions, which were taken from the 1999 NEC, are essential to employee safety. OSHA agrees with the consensus of NFPA's expert opinion that these requirements are reasonably necessary to protect employees and has included them in the proposed rule. On occasion, OSHA has rewritten the provision to lend greater clarity to its requirements. However, these editorial changes to the language of NFPA 70E do not represent substantive differences. NFPA's handling of these provisions and the rationale underpinning them is a matter of public record for the NEC and NFPA 70E. OSHA agrees with the rationale in this record as it pertains to the new and revised provisions the Agency is proposing. OSHA has placed the public record on all editions of the NEC and NFPA 70E after 1978 into the public docket for this rulemaking.

D. Branch Circuits-Ground Fault Circuit Interrupters for Employees

Introduction.

Each year many employees suffer electric shocks while using portable electric tools and equipment. The nature of the injuries ranges from minor burns to electrocution. Electric shocks produced by alternating currents of power line frequency passing through the body of an average adult from hand to foot for 1 second can cause various effects, starting from a condition of being barely perceptible at 1 milliampere to loss of voluntary muscular control from 9 to 25 milliamperes. The passage of still higher currents can produce ventricular fibrillation of the heart from 75 milliamperes to 4 amperes and, finally, immediate cardiac arrest at over 4 amperes. These injuries occur when employees contact electrically energized parts. Typically, the frame of a tool becomes accidentally energized because of an electrical fault that provides a conductive path to the tool casing. When the employee contacts the tool casing, the fault current flows through the employee to ground. The amount of current that flows through an employee depends, primarily, upon the resistance of the fault within the tool, the resistance of the employee, and the resistance of the path from the employee back to the electric power supply. Moisture in the atmosphere can contribute to the electrical fault by intensifying both the conductive path within the tool and the external path back to the electric power supply. Dry skin can have a resistance range of about 500 to 500,000 ohms and wet skin can have a resistance range of about 200 to 20,000, depending on several factors, such as the weight of the employee. Thus, more current will flow if the employee is perspiring or becomes wet because of environmental conditions.

One method of protection against injuries from electric shock is the ground-fault circuit interrupter (GFCI). This device continually monitors the current flow to and from electric equipment. If the current going out of the equipment differs by 0.005 amperes from the current returning, then the GFCI will deenergize the equipment within as little as 25 milliseconds, quickly enough to prevent electrocution.

GFCI requirements.

Proposed § 1910.304(b)(4) would set new requirements for ground-fault circuit interrupter protection of receptacles and cord connectors used in general industry. As noted earlier, this provision would only apply to installations made after the effective date of the final rule. Paragraph (b)(4)(i) would require ground-fault circuit protection for 125-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms and on rooftops. Cord- and plug-connected equipment in these locations can get wet and expose employees to severe ground-fault hazards. The NFPA 70E Committee believes, and OSHA agrees, that using 125-volt, 15- and 20-ampere cord- and plug-connected equipment in these locations exposes employees to a risk of electrocution great enough to warrant the protection afforded by ground-fault circuit interrupters.

Paragraph (b)(4)(ii) would require ground-fault circuit interrupter protection for receptacles on temporary wiring installations that are used during maintenance, remodeling, or repair of buildings, structures, or equipment, or during similar activities. However, receptacles on a 2-wire, single-phase portable or vehicle-mounted generator rated not more than 5 kW would be permitted without ground-fault circuit-interrupter protection if the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces.

OSHA currently requires GFCI protection for 120-volt, 15- and 20-ampere temporary receptacle outlets used on construction sites (§ 1926.404(b)(1)). In the 26 years that this requirement has been in effect, the Agency estimates that between 500 and 750 lives have been saved because of it.

Temporary wiring associated with construction-like activities exposes employees to the same ground-fault hazards as those associated with temporary receptacle outlets on construction sites. In § 1910.304(b)(4)(ii), OSHA is proposing to extend this requirement to temporary receptacles used in construction-like activity performed in general industry. The proposal would extend protection to receptacles of higher voltage and current ratings. This will better protect employees from ground-fault hazards than the construction rule because it covers other equipment that is just as subject to damage as 120-volt, 15- and 20-ampere equipment and that is more prevalent today than when the construction rule was promulgated.

In the preamble to the final rule adopting a requirement for GFCIs on construction sites, OSHA estimated that there were between 30 and 45 deaths per year caused by 120-volt ground faults on construction sites, and the Agency determined that nearly all of those deaths could be prevented by the use of GFCIs or an assured grounding program (41 FR 55701). OSHA fatality investigation data indicate that only 46 deaths involving 120-volt ground-faults in temporary wiring occurred over the years 1990 to 1996 (the latest year for which data are complete). This is a death rate of only 6.6 per year. Thus, OSHA believes that the rule has saved between 24 and 39 lives per year or, over the 25 years the rule has been in effect, a total of between 600 and 975 lives.

The Agency is not proposing to permit the NFPA 70E assured grounding program as an alternative to GFCIs in general industry and maritime employment. NFPA 70E's assured grounding program differs in several important respects from the assured grounding program in OSHA's construction standards. For example, NFPA 70E permits the assured grounding program as an alternative to GFCIs only (1) for industrial establishments with conditions of maintenance and supervision that ensure that only qualified personnel are involved and (2) for receptacle outlets rated other than 125 volts and 15, 20, or 30 amperes. The OSHA construction rule recognizes the assured grounding

program as an alternative to GFCIs without restriction. Additionally, under the assured grounding program, NFPA 70E requires electric equipment to be tested only when there is evidence of damage. This is in contrast to the assured grounding program required by OSHA's construction standard, which requires electric equipment to be tested after any incident that can reasonably be suspected to have caused damage. OSHA believes that these differences would be confusing for employers who are subject to both standards and would offer less protection for employees.

OSHA also considered including the assured grounding program requirements from the construction standard as an alternative to GFCIs in this proposed rule. However, the Agency believes that GFCIs alone, without the assured grounding program as an alternative will provide better protection for employees. The construction standard's assured grounding program demands constant vigilance on the part of employees to provide them with the same level of protection as GFCIs. Under that program, employers must test cord- and plug-connected equipment generally at 3-month intervals, and employees must inspect them daily. In contrast, GFCIs constantly monitor the circuit for ground faults and open the circuit when ground-fault current becomes excessive without the need for either the employer or the employee to take. Considering that three fourths of all electrical accidents are caused by poor work practices (55 FR 31986), OSHA believes that GFCIs are a much more reliable method of protecting employees.

For these reasons, OSHA believes that this proposal would afford better protection for employees than NFPA 70E. However, OSHA requests comments on whether the assured grounding program required by the electrical standards for construction in § 1926.404(b)(1)(iii) provides equal or better protection for employees than GFCIs, and whether it should be added as an alternative to GFCIs in the general industry electrical installation standard.

E. Carnivals, Circuses, Fairs, and Similar Events

The proposed standard has new requirements for carnivals, circuses, exhibitions, fairs, traveling attractions, and similar events. These requirements, which are based on corresponding requirements in NFPA 70E, would cover the installation of portable wiring and equipment for these temporary attractions. From 1991 to 2002, OSHA received reports of 46 serious accidents

associated with carnivals, circuses, exhibitions, fairs, and similar events. Eleven of these accidents, resulting in 10 fatalities and 5 injuries, involved electric shock. Eight of those 11 cases (8 fatalities and 1 injury) involved electric wiring and equipment covered by the installation requirements in Subpart S. OSHA believes that the new electrical requirements for these events will prevent similar accidents in the future.

These accidents were investigated by OSHA generally in response to employer reports of a fatality or three or more hospitalized injuries.

In paragraph (k) of § 1910.306, mechanical protection of electric equipment and wiring methods would be required in and around rides, concessions, or other units subject to physical damage. Inside tents and concession stands, the electrical wiring for temporary lighting would need to be secured and protected from physical damage. These new provisions would provide more electrical safety for employees working in and around this equipment.

The disconnecting means would need to be readily accessible to the operator; that is, the fused disconnect switch or circuit breaker would have to be located within sight and within 6 feet of the operator for concession stands and rides. This provision would provide protection by enabling the operator to stop the equipment in an emergency. The disconnecting means would also have to be lockable if it is exposed to unqualified persons, to prevent such persons from operating it.

F. Zone Classification

Introduction.

Section 1910.307 contains OSHA's electrical safety requirements for locations that can be hazardous because of the presence of flammable or combustible substances. Hazardous locations are currently classified according to the properties of flammable vapors, liquids or gases, or combustible dusts or fibers that may be present. These locations are designated in the NEC and § 1910.307 as one of six types: Class I, Division 1; Class I, Division 2; Class II, Division 1; Class II, Division 2; Class III, Division 1; and Class III, Division 2. This system is called the “division classification system,” or the “division system.” The NEC first addressed this system in 1920. The OSHA website has a short but informative paper on this topic, which is available at

http://www.osha.gov/doc/outreachtraining/htmlfiles/hazloc.html.

The latest version of NFPA 70E incorporates an alternative system (in addition to the division classification system) for installing electric equipment in Class I locations. (Class II locations continue under the division system.) This system is called the “zone classification system,” or the “zone system.” The zone system designates three classifications: Class I, Zone 0; Class I, Zone 1; and Class I, Zone 2. The zone system is based on various European standards that were developed by the International Electrotechnical Commission (IEC).

A modified version of this system was first adopted into the NEC in the 1996 edition. Although the zone and division classification systems differ in concept, individual equipment can be approved for use under both systems when the equipment incorporates protective techniques for both systems (as determined by the nationally recognized testing laboratory that lists or labels the equipment).

The IEC prepares and publishes international standards for all electrical, electronic and related technologies. This global organization is made up of members from more than 60 participating countries, including the U.S.

The zone system is an alternative method to the division system; employers may use either system for installations of electric equipment in Class I hazardous locations. OSHA proposes to permit the use of the zone system under § 1910.307 and any other OSHA standard that references § 1910.307.

As noted earlier, OSHA is proposing in § 1910.307(b) to require employers to document the designation of hazardous locations within their facilities. The documentation must denote the boundaries of each division or zone so that employees who install, inspect, maintain, or operate equipment in these areas will be able to determine whether the equipment is safe for the location. As noted earlier, OSHA is proposing to require documentation for the division system only for new installations that use that system. It would apply to all installations made under the zone system.

Proposed changes to OSHA's existing requirements for the division classification system.

The term “hazardous concentrations” is currently used in various definitions of specific hazardous locations in § 1910.399. For example, § 1910.399 defines “Class I, Division 1,” in part, as follows:

A Class I, Division 1 location is a location: (a) in which hazardous concentrations of flammable gases or vapors may exist under normal operating conditions * * *

The proposal would change the term “hazardous concentrations” to “ignitable concentrations” in each of the

definitions. This change would reflect changes already incorporated into the 1999 NEC and the 2000 edition of NFPA 70E to make the definition more specific about the hazard being addressed. The changes will make these definitions clearer in addition to making the OSHA standard consistent with the latest editions of NEC and NFPA 70E.

OSHA is also proposing to add a new paragraph (f) to § 1910.307 that sets acceptable protection techniques under the division system. These requirements address design features that must be used to protect employees who are using equipment in a hazardous location classified under the division system. Neither the current Subpart S nor NFPA 70E explicitly require specific protection techniques that may be used in the division classification system; however, the NEC does require specific protection techniques for installations made under the division classification system in various requirements spread throughout the Articles covering hazardous locations. OSHA has listed these techniques in one paragraph in the proposal to make the standard easier to use and to provide parallel requirements for both the division classification system and the zone classification system. Protective techniques other than those listed in paragraph (f) are acceptable if the equipment is: (1) Intrinsically safe as specified in § 1910.307(c)(1); approved for the specific hazardous location as specified in § 1910.307(c)(2); or (3) of a type and design that the employer demonstrates is safe for the specific hazardous location as specified in § 1910.307(c)(3). New paragraph (f) is intended to clarify the existing OSHA requirements for hazardous locations by explicitly listing the types of protective techniques used under the division classification system. (The protection techniques are required implicitly under the existing standard through the requirements for approval and listing or labeling by a nationally recognized testing laboratory and through the reference to the National Electrical Code in the note following § 1910.307(b)(3).)

Brief background and description of the zone system.

The zone system stemmed from the independent efforts of countries in Europe and elsewhere to develop an area classification system to address safety in locations containing hazardous substances. The IEC formalized these efforts into the zone system, which is now used to classify the majority of the world's hazardous location systems.

Brenon, M., Kelly, P., McManama, K., Klausmeyer, U., Shao, W., Smith, P., “The Impact of the IECEx Scheme on the Global Availability of Explosion Protected Apparatus,”

Record of Conference Papers of the 1999 Petroleum and Chemical Industry Technical Conference

, September 13-15, 1999, Paper No. PCIC-99-07, pp. 99-109.

Article 505 of the 1996 NEC included requirements for the U.S. version of the zone system for the first time. The current version of NFPA 70E (NFPA 70E-2000) includes requirements for the zone system based on the 1999 version of the NEC. OSHA is proposing to adopt zone system rules that are based on these NFPA 70E provisions. This will permit electric equipment approved for use in hazardous locations to be used in U.S. workplaces, under either the division or zone system.

Major differences between the division classification system and the zone classification system.

The zone system can best be described by comparing it with the division system. Both systems characterize locations by the likelihood and circumstances under which flammable gases or vapors exist. The systems both define the types of gases or vapors that may exist and categorize them under a number of groups. Each system specifies an allowable range of operating temperature, and corresponding requirements, for electric equipment used in a particular division or zone.

In contrast to the division system, however, the zone system is only used to classify areas that are hazardous because of the presence of flammable gases or vapors (Class I locations). The division system must be used to classify areas that may contain combustible dusts or easily ignitable fibers or flyings (Class II and III locations, respectively).

The zone system defines three types of Class I locations (Zones 0, 1, and 2) rather than two locations under the division system (Divisions 1 and 2). Zones 0 and 1 equate to Division 1, whereas Zone 2 equates to Division 2. In a Class I, Division 1 location, flammable gases or vapors are or may be present in the air in ignitable concentrations. In a Class I, Zone 1 location, ignitable concentrations of flammable gases or vapors are not always present, but such concentrations may exist periodically even under normal conditions. By contrast, in a Class I, Zone 0 location, such gases or vapors are present either continuously or for long periods of time. (See Table 2.) Thus, a Class I, Zone 0 location is, in essence, a worst-case Class I, Division 1 location.

Each system classifies flammable gases and vapors into a number of groups. The division system has four such groups, designated A, B, C, and D, with group A containing the most volatile substances, and groups B, C, and D containing gases or vapors that are progressively less volatile. The zone system has three such groups, designated IIA, IIB, and IIC, with group IIC containing the most volatile gases, and groups IIA and IIB containing gases or vapors that are progressively less volatile. Substances classified under Groups A and B in the division system generally fall under Group IIC of the zone system. However, some differences exist between the groups in the two systems. Thus, regardless of the classification system being used, equipment intended for use in a Class I hazardous location must indicate the groups for which it is approved, as required by proposed § 1910.307(c)(2)(ii) and (g)(5)(ii). Table 2 summarizes the similarities and differences between the two systems.

The other major differences concern the allowable protection schemes and the maximum allowable surface temperature of equipment under each system. The protection schemes acceptable for each division and zone are listed in Table 3, and the remainder of this paragraph discusses the differences in maximum allowable temperature. According to the NEC, equipment is acceptable for a hazardous location only if its surface temperatures will not approach the ignition temperature, or more specifically the autoignition temperature, of the particular gases and vapors that might be present in that location. There are 14 temperature limits, and corresponding identification codes, under the division system. Each limit specifies the maximum surface temperature for equipment labeled with the matching code. There are six such temperature limits and corresponding identification codes under the zone system. The six zone system limits correspond directly to 6 of the 14 division system temperature limits. However, as shown in Table 2, the remaining eight division temperature limits have values intermediate to the six zone system temperature limits. For example, the division system has 4 intermediate temperature limits, 215°C, 230°C, 260°C, and 280°C (T2D, T2C, T2B, and T2A, respectively), between the zone system's temperature limits of 200°C (T3) and 300°C (T2). Equipment approved for one of these intermediate values may be used under the zone system only for the higher (in temperature) of the two closest zone system values. For example, equipment marked T2A under the division system, which has a maximum surface temperature of 280°C,

could only be used in locations where the ignition temperature of the substance is greater than or equal to the T2 value, which is 300°C. In essence, T2A equipment becomes derated to T2 equipment when it is installed using the zone classification system. It could not be used in zone-classified locations where the ignition temperature of the substance is less than or equal to the T3 value, which is 200°C, because the equipment could become hot enough to cause ignition.

More details on the differences in gas groups.

In the 1999 NEC, the definitions for each of the division system gas and vapor groups, except Group A,

were changed to make them comparable to the definitions of the zone system groups. A gas or vapor is classified in the division system's Group B, C, or D or the zone systems Group IIC, IIB, or IIA based on the gas's or vapor's maximum experimental safe gap (MESG)

or its minimum igniting current ratio (MIC ratio).

These values are established under standard experimental conditions for each gas and vapor.

Acetylene is the only Group A gas under the division system.

The MESG is the maximum clearance between two parallel metal surfaces that has been found, under specified test conditions, to prevent an explosion in a test chamber from being propagated to a secondary chamber containing the same gas or vapor at the same concentration.

The MIC ratio is the ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under the same test conditions.

The 1999 NEC indicates two factors that may affect MESG and MIC values: (1) Lower ambient temperatures (lower than minus 25°C or minus 13°F), and (2) oxygen enriched atmospheres. The 1999 NEC Handbook states that the latter factor can drastically change the explosion characteristics of materials. Such an atmosphere lowers the minimum ignition energy, increases the explosion pressure, and can reduce the maximum experimental safe gap. These factors would make it unsafe to use otherwise approved “intrinsically safe” and “explosion-proof” equipment, unless the equipment has been tested for the specific conditions involved. Employers must ensure that the equipment approval is valid for the actual conditions present where the equipment is installed. This is required generally for all electric equipment. However, it is essential in hazardous locations because of the dire consequences that may result.

Rationale for adopting the zone system requirements.

As stated earlier, the zone system has been accepted in many countries. Such international acceptance has meant that U.S. manufacturers of electric equipment suitable for installation in hazardous locations have had to ensure that their equipment met the zone system requirements if they wished to sell such equipment in zone-system countries in addition to meeting the U.S. division system requirements. Also, U.S. employers that had hazardous locations in their workplaces have sought to use equipment approved for use only in zone-classified locations in this country. This, in turn, led NFPA to incorporate the zone system in the NEC starting in the 1996 edition.

OSHA has determined that employees can be protected from the hazards of explosion in Class I hazardous locations by the installation of electric equipment following the latest NEC requirements for the zone classification system (Article 505 of the 2002 NEC). Therefore, the Agency is incorporating the zone system in this proposed revision of the electrical installation requirements in Subpart S. Under the proposed standard, employers would be able to comply with either the zone classification system or the division system for Class 1 hazardous locations.

New § 1910.307(g) and related definitions.

OSHA is proposing to add a new paragraph (g) to § 1910.307 to cover the zone classification system. This new paragraph addresses the following topics: scope; location and general requirements; protection techniques; special precaution; and listing and marking. A brief description of the contents of each paragraph follows.

Paragraph (g)(1) permits employers to use the zone classification system as an alternative to the division classification system. This paragraph also explains that the requirements in § 1910.307 that are specific to installations built under the division classification do not apply to installations built under the zone classification system. Thus, paragraph (c), electrical installations; paragraph (d), conduits; paragraph (e), equipment in Division 2 locations; and paragraph (f), protection techniques do not apply to installations built under the zone system. Paragraph (g) contains counterparts to each of these requirements.

Paragraphs (g)(2)(i) and (ii) describe how hazardous locations are classified under the zone system. The employer must consider each individual room, section, or area separately and must designate locations according to the specific properties of the flammable gases, liquids, or vapors that might be present. The same requirements apply to the division system. (See § 1910.307(a).)

Paragraphs (g)(2)(iii) and (g)(2)(iv) require that conduit threads be of certain types and that connections be made wrench tight. These provisions ensure that there is no arcing across conduit connections in the event that they have to carry fault current. Paragraph (d) contains similar requirements for division system installations.

Paragraph (g)(3) presents the protection techniques that are acceptable in zone-classified hazardous locations. Electric equipment in these locations must incorporate at least one of these protection techniques, and the equipment must be approved for the specific hazardous location. The protection techniques listed in the proposal have been taken directly from NFPA 70E-2000.

Paragraph (g)(4) sets special precautions that must be taken with respect to hazardous locations classified under the zone system. First, the classification of areas and the selection of equipment and wiring must be under the supervision of a qualified professional engineer. This provision is contained in NFPA 70E-2000 and in the 1999 NEC. Because the zone system has been permitted in the U.S. only since 1997,

employers and installers in this country have relatively little experience with installations made using the zone classification system. The experts that developed NFPA 70E and the NEC have determined that, for the zone system, it is essential for competent persons to classify the hazardous locations and select equipment for those locations. OSHA agrees with these experts. Paragraph (g)(4) also indicates when it is safe to have locations classified using the division system on the same premises as locations classified under the zone system and vice versa. These provisions are also taken from NFPA 70E-2000.

As noted earlier, the zone system was first incorporated into the NEC in the 1996 edition. This edition was adopted by various governmental jurisdictions beginning in 1997. Installations made using the zone system were not permitted by these jurisdictions before then. In addition, the existing OSHA standard does not permit classifying hazardous locations under the zone system, and employers have not been certain that installations made using the zone classification systems would be acceptable to OSHA.

Paragraph (g)(5) contains requirements for marking equipment that is approved for hazardous locations classified under the zone system. These provisions are comparable to the corresponding marking requirements under the division system, but reflect the need to provide information

necessary for safely installing equipment in a zone-classified location.

Equivalence of systems and permitted protection techniques.

Table 2 shows the general equivalence between the two classification systems. It should be noted, however, that a given area classified under one system is not permitted to overlap an area classified under the other system. For example, although Division 2 and Zone 2 are basically equivalent classifications, under the proposed standard a Zone 2 location is permitted to touch a Division 2 location, but the two locations are not permitted to overlap. This ensures that equipment installed and maintenance performed in these locations are appropriate for the conditions in each location.

Division 2 and Zone 2 are basically equivalent classifications, but there are some differences in what types of equipment are acceptable in each of those locations. See, for example, the earlier discussion on maximum allowable surface temperatures.

Table 2.—Equivalence of Hazardous (Classified) Location Systems, Class I Locations Only