# 62 Ill. Adm. Code 220.90: Section 220.90 Low and Medium-Voltage Alternating Current Circuits

> Illinois · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T62_P220_S220_90

## Section

- **Citation:** 62 Ill. Adm. Code 220.90
- **Heading:** Section 220.90 Low and Medium-Voltage Alternating Current Circuits
- **Jurisdiction:** Illinois
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Illinois Administrative Code / Title 62 MINING / CHAPTER I: DEPARTMENT OF NATURAL RESOURCES / Part 220 SURFACE INSTALLATION HEALTH AND SAFETY / Section 220.90 Low and Medium-Voltage Alternating Current Circuits

## Text

Section 220
Section 220.90  Low and
Medium-Voltage Alternating Current Circuits
a)         Low-voltage and medium-voltage circuits serving portable,
mobile and stationary, three (3)-phase alternating-current equipment;
protective devices.
1)         Low and medium-voltage circuits supplying power to portable or
mobile three (3)-phase alternating-current equipment shall be protected by
suitable circuit breakers of adequate interrupting capacity, which are properly
tested and maintained and equipped with devices to provide protection against
grounded phase, short circuit, and overload.
2)         Low and medium-voltage circuits supplying power to stationary
equipment shall be deenergized with the occurrence of an overload or, short
circuit, by a circuit breaker, or fuses of the correct type and capacity. Such
devices shall, in addition, on solidly grounded or resistance grounded systems
deenergize the circuit on the occurrence of a phase-to-ground fault.
Ungrounded low and medium-voltage circuits supplying power to stationary
equipment shall be provided with ground detectors to indicate visually the
presence of a grounded on any phase.  Other no less effective devices may be
approved by an authorized representative of the Department.
b)         Testing, examination, and maintenance of circuit breaker;
procedures.
1)         Circuit breakers and their auxiliary devices shall be tested
and examined at least once each month by a qualified person.
2)         In performing such tests, the circuit breaker auxiliaries or
control circuits shall be actuated in any manner which causes the circuit
breaker to open.  In the absence of auxiliaries or control circuits, the
breaker will be operated manually.  All components of the circuit breaker and
its auxiliary devices shall be visually examined and such repairs or
adjustments as are indicated by such tests and examinations shall be carried out
immediately.
c)         Testing, examination, and maintenance of circuit breakers;
record
uit
breaker to open.  In the absence of auxiliaries or control circuits, the
breaker will be operated manually.  All components of the circuit breaker and
its auxiliary devices shall be visually examined and such repairs or
adjustments as are indicated by such tests and examinations shall be carried out
immediately.
c)         Testing, examination, and maintenance of circuit breakers;
record.
The operator shall maintain a written record of each test,
examination, repair, or adjustment of all circuit breakers protecting low and
medium-voltage circuits serving three (3)-phase alternating-current equipment
and such record shall be kept in an approved book.
d)         Low-voltage and medium-voltage three (3)-phase circuits;
system grounding.
1)         Low-voltage and medium-voltage circuits supplying power to
portable or mobile three (3)-phase alternating-current equipment shall contain:
A)        Either a direct or derived neutral grounded through a suitable
resistor as the power source; or
B)        A grounding circuit originating at the grounded side of the
grounding resistor which extends along with the power conductors and serves as
a grounding conductor for the frames of all the electric equipment supplied
power from the circuit.
2)         Grounding resistors shall be connected to a low resistance
ground field, and shall be of an CHMIC value which limits the ground fault
current to no more than twenty-five (25) amperes.  Such grounding resistors
shall be rated for maximum fault current continuously and provide insulation
from ground for a voltage equal to the phase-to-phase voltage of the system.
e)         Grounding resistors; continuous current-rating.
The ground
fault current rating of grounding resistors shall meet the "extended time
rating" set forth in American Institute of Electrical Engineers Standard
No. 32.
f)         Low-voltage and medium-voltage ground check circuits.
Present
technology does not provide for a fail safe ground monitor system
-to-phase voltage of the system.
e)         Grounding resistors; continuous current-rating.
The ground
fault current rating of grounding resistors shall meet the "extended time
rating" set forth in American Institute of Electrical Engineers Standard
No. 32.
f)         Low-voltage and medium-voltage ground check circuits.
Present
technology does not provide for a fail safe ground monitor system.  In the
event such technology becomes available, The Mining Board has the authority to
adopt rules requiring such systems.
g)         Systems grounding.
Three
(3)-phase low-voltage and medium-voltage circuits of more than two hundred
forty (240) volts phase-to-phase extending to stationary equipment shall be
grounded in one of following ways:
1)         Solidly grounded through a direct or derived neutral;
2)         Contain a direct or derived neutral grounded through a
suitable resistor located at the power source; or
3)         Ungrounded Delta.
h)         Disconnecting devices.
Disconnecting
devices shall be installed at the beginning of each branch line supplying power
to each piece of portable or mobile equipment and shall provide visual evidence
that the power is disconnected.
i)          Connection of single-phase loads.
Single-phase
loads shall be connected phase-to-phase in resistance grounded systems.
j)          Qualified person.
An individual
is a qualified person within the meaning of this Section 220.90 of this Part,
if such person is a qualified person under Section 220.50(e) of this Part.

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T62_P220_S220_90. Check the current official text before relying on it. Not legal advice.