Instantaneous vs. Inverse Time Circuit Breakers for Motors

Instantaneous vs. Inverse Time Circuit Breakers for Motors

What difference does it make?

Article 430 in the National Electrical Code (NEC) recognizes two types of molded case circuit breakers (MCCBs) — instantaneous and inverse time — for motor branch circuit short circuit and ground fault protection, in addition to fuses. There’s an important difference between these two types of circuit breakers.

Instantaneous trip breakers do exactly what the name implies. When the current in the circuit reaches a value that the breaker trip mechanism is set to, it will trip of

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