Title 46
SECTION 129.380
129.380 Overcurrent protection.
§ 129.380 Overcurrent protection.(a) Overcurrent protection must be provided for each ungrounded conductor, to open the electric circuit if the current reaches a value that causes an excessive or dangerous temperature in the conductor or its insulation.
(b) Each conductor of a control, interlock, or indicator circuit, such as a conductor for an instrument, pilot light, ground-detector light, or potential transformer, must be protected by an overcurrent device.
(c) Each generator must be protected by an overcurrent device set at a value not exceeding 115 percent of the generator's full-load rating.
(d) Circuits of control systems for steering gear must be protected against short circuit.
(e) Each feeder circuit for steering gear must be protected by a circuit breaker that complies with §§ 58.25-55(a) and (b) of this chapter.
(f) Each branch circuit for lighting must be protected against overcurrent by either fuses or circuit breakers. Neither the fuses nor the circuit breakers may be rated at more than 30 amperes.
(g) Each conductor must be protected in accordance with its current-carrying capacity. If the allowable current-carrying capacity does not correspond to a standard size of device, the next larger overcurrent device may be used, provided it is less than 150 percent of the conductor's current-carrying capacity.
(h) An overcurrent device must be installed to protect each motor conductor and control apparatus against overcurrent due to short circuit or ground fault. Each overcurrent device must be capable of carrying the starting current of the motor.
(i) An emergency switch must be provided in each normally ungrounded main supply conductor from a battery. The switch must be accessible from the battery and located as close as practicable to it.
(j) No grounded conductor of a circuit may be disconnected by a switch or circuit breaker unless the ungrounded conductors are all simultaneously disconnected.
(k) A means of disconnect must be provided on the supply side of and adjacent to each fuse, to de-energize the fuse for inspection and maintenance.
(l) A way for locking the means of disconnect open must be provided unless the means of disconnect for a fused circuit is within sight of the equipment that the circuit supplies.
(m) Each fuse must be of the cartridge type and be listed by Underwriters Laboratories (UL) or another independent laboratory recognized by the Commandant.
(n) Each circuit breaker must meet UL 489 and be of the manually-reset type designed for -
(1) Inverse delay;
(2) Instantaneous short-circuit protection; and
(3) Switching duty if the breaker is used as a switch.
(o) Each circuit breaker must indicate whether it is open or closed.