The primary intent of this discussion is to explain how overcurrent protection devices are determined for single motor branch-circuits. References will be taken from the 2020 National Electrical Code (NEC). These references will apply to general single motor applications for a continuous duty NEMA Design B energy efficient motor, unless otherwise noted.
Electricity operates within predictable boundaries. We have come to identify these boundaries as Ohm’s Law. Ohm’s Law was developed as a means of explaining how electricity operates within a closed circuit. The Ohm’s Law formula helps to communicate the relationship between different properties within an electrical circuit. We can use Ohm’s Law to explain what has occurred, as well as what will occur, when certain conditions are imposed upon an electrical circuit.
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