Each sign and outline lighting system shall be controlled by an externally operable switch or circuit breaker that opens all ungrounded conductors simultaneously on _____ branch circuits.
a) 15A
b) 20A
c) multiwire
d) outdoor
See answer and applicable Code reference
The correct answer is: c) multiwire
Article 600 covers the installation of conductors, equipment, and field wiring for electric signs and outline lighting. As noted in the first two sentences of Sec. 600.6, "Each sign and outline lighting system, feeder circuit or branch circuit supplying a sign, outline lighting system, or skeleton tubing shall be controlled by an externally operable switch or circuit breaker that opens all ungrounded conductors and controls no other load. The switch or circuit breaker shall open all ungrounded conductors simultaneously on multiwire branch circuits in accordance with 210.4(B)."