Overload devices are intended to protect motors, motor control apparatus, and motor branch-circuit conductors against _____.
a) excessive heating due to motor overloads
b) excessive heating due to failure to start
c) short circuits and ground faults
d) excessive heating due to motor overloads and failure to start
See answer and applicable Code reference
The correct answer is: d) excessive heating due to motor overloads and failure to start
You'll find the rules for motor and branch-circuit overload protection in Part III of Art. 430 in the 2011 NEC. As noted in the first sentence of Sec. 430.31, "Part III specifies overload devices intended to protect motors, motor-control apparatus, and motor branch-circuit conductors against excessive heating due to motor overloads and failure to start."
