USCG Exam PracticeElectrical troubleshooting and maintenance
A feeder circuit on a vessel is isolated from the main switchboard by a transformer. Per 46 CFR §111.05-23, where must a ground indicator be provided for this feeder circuit, and what alternative arrangement is explicitly permitted?
- A. Only at the main switchboard; no alternative arrangement is permitted
- B. Only at the transformer secondary terminals; relocation to the main switchboard is not permitted
- ✓ At the distribution switchboard or another location such as a centralized monitoring position; an alarm contact returned to the main switchboard via control cable is permitted so detecting equipment can remain near the transformerCorrect
- D. At both the main switchboard and the transformer simultaneously; no single-location alternative is acceptable
Why C is correct
46 CFR §111.05-23(d) requires a ground indicator for each transformer-isolated feeder circuit at the distribution switchboard or at another location such as a centralized monitoring position. The Note to paragraph (d) explicitly permits an alarm contact or indicating device returned to the main switchboard via control cable, allowing the detecting equipment to remain near the transformer for local troubleshooting.
Cited:46 CFR §111.05-23