An industrial oven keeps tripping its breaker intermittently. A tech checks the amp draw and finds it steady at 38A on a 40A breaker. Why is the breaker tripping?
Answers
AThe continuous load exceeds 80% of the breaker rating
BThe oven has a severe ground fault
CThe voltage is fluctuating too much
DThe breaker is defective and must be replaced
Correct answer: A — The continuous load exceeds 80% of the breaker rating
Standard breakers are rated to carry 80% of their rating continuously. 80% of 40A is 32A. A 38A continuous load will cause the thermal element to trip eventually.
MIFOTRA exam practicealigned to NFPA 70 / IEC 60364·3 marks·Medium