USCG Exam PracticeSwitchboards and distribution systems
Under 46 CFR §111.05-37, under what condition may an overcurrent device be installed in a permanently grounded conductor?
- A. When the overcurrent device is a fuse rated at 125% of the conductor ampacity
- ✓ When the overcurrent device simultaneously opens each ungrounded conductor of the circuitCorrect
- C. When the grounded conductor is part of the emergency-main switchboard bus-tie
- D. When the overcurrent device is a ground fault circuit interrupter rated for marine use
Why B is correct
46 CFR §111.05-37(a) prohibits an overcurrent device in a permanently grounded conductor unless that device simultaneously opens each ungrounded conductor of the circuit. The neutral of the emergency-main switchboard bus-tie is specifically prohibited from having any switch or circuit breaker under §111.05-37(b).
Cited:46 CFR §111.05-37