USCG Exam PracticeSwitchboards and distribution systems
A permanently grounded conductor in a shipboard distribution system has an overcurrent device installed in it. Under 46 CFR §111.05-37, this installation is permissible only if which condition is met?
- A. The overcurrent device is rated at no more than 125 percent of the conductor's ampacity
- ✓ The overcurrent device simultaneously opens each ungrounded conductor of the circuitCorrect
- C. A ground fault indicator is installed on the same panel to detect neutral current
- D. The overcurrent device is a fuse rather than a circuit breaker to limit interrupting energy
Why B is correct
46 CFR §111.05-37(a) permits an overcurrent device on a permanently grounded conductor only if that device simultaneously opens each ungrounded conductor of the circuit. This prevents the neutral from being opened while ungrounded conductors remain energized, which would create a shock hazard.
Cited:46 CFR §111.05-37