From the Chicago Code Book
18-27-210.6. Branch Circuit Voltage Limitations.
(a) Occupancy Limitations. In dwelling units and guest rooms of hotels, motels, and similar occupancies, the voltage shall not
exceed 120 volts, nominal, between conductors that supply the terminals of:
(1) Lighting fixtures;
(2) Cord- and plug- connected loads of less than 1440 volt-amperes nominal.
(b) 120 volts Between Conductors. Circuits not exceeding 120 volts nominal, between conductors shall be permitted to supply the
following:
(1) The terminals of medium-base screw-shell lampholders or lampholders of other types applied within their voltage ratings;
(2) Auxiliary equipment of electric discharge lamps;
(3) Cord and plug connected or permanently connected utilization equipment.
(c) 277 Volts to Ground. Provided the premises is under the supervision of a Supervising Electrician employed by the company or
by a contract with a registered electrical contractor, circuits exceeding 120 volts, nominal, between conductors and not exceeding 277
volts, nominal, to ground shall be permitted to supply the following equipment:
(1) Lighting fixtures equipped with mogul-base screw shell lampholders or with lampholders other than the screw shell-type applied
within their voltage ratings provided:
(a) The light fixtures are installed at least 8 ft above the floor;
(b) The light fixtures have a conspicuous warning notice within the wiring compartment indicating the circuit voltage;
(c) The light fixtures are permanently installed;
(d) Switching is by low-voltage remote control relays or by circuit breakers within the branch circuit distribution panel;
(e) Circuit interrupting toggle switches are not used;
(f) The lighting fixtures do not have integral switches.
(2) Auxiliary equipment of electric discharge lamps provided:
(a) The light fixtures are installed at least 8 ft above the floor;
(b) The light fixtures have a conspicuous warning notice within the wiring compartment indicating the circuit voltage;
(c) The light fixtures are permanently installed;
(d) Switching is by low-voltage remote control relays or by circuit breakers within the branch circuit distribution panel;
(e) Circuit interrupting toggle switches are not used;
(f) The lighting fixtures does not have integral switches.
(3) Permanently installed and connected utilization equipment provided:
(a) The equipment has a conspicuous warning notice within the wiring compartment indicating the circuit voltage;
(b) The equipment is permanently installed;
(c) Switching is by low-voltage remote control relays or by circuit breakers within the branch circuit distribution panel;
(e) Circuit interrupting toggle switches are not used.
(f) Kitchen equipment is not installed at voltages of more than 150 volts to ground.
(d) 600 Volts Between Conductors. Provided the premises is under the supervision of a Supervising Electrician employed by the
