USCG Exam PracticeElectrical basics — generators, motors, and safety
A generator or motor is designed for a 40 °C ambient temperature rating. It must be installed in a space where ambient temperature reaches 50 °C. Under what condition may it be used in that space?
- A. It may be used without restriction provided it has a nameplate from a certified manufacturer
- B. It may be used only if the overcurrent device is removed entirely
- ✓ It may be used if derated to 80 percent of full load rating with overcurrent devices reduced accordinglyCorrect
- D. It may be used if derated to 90 percent of full load rating with no change to overcurrent devices
Why C is correct
46 CFR §183.320(b)(2) permits a 40 °C-rated generator or motor to be used in a 50 °C ambient location provided it is derated to 80 percent of its full load rating and the rating or setting of the overcurrent devices is reduced accordingly.
Cited:46 CFR §183.320