Motor Combination Starter

[FaradayFF]

Hi,

I've been reading NEC motor section and came to a conclusion that if a motor has a separate overload relay, the motor doesn't need to be protected by a thermal magnetic breaker. Magnetic circuit protector can be used to protect wiring and provide short circuit protection for this configuration.

Am I right here?

Thanks,
EE

 

[texie]

Hi,

I've been reading NEC motor section and came to a conclusion that if a motor has a separate overload relay, the motor doesn't need to be protected by a thermal magnetic breaker. Magnetic circuit protector can be used to protect wiring and provide short circuit protection for this configuration.

Am I right here?

Thanks,
EE

Yes, if it is a factory assembled combination motor starter. You can not field build this.

 

[augie47]

Your Code reference is 430.109
(4) Instantaneous Trip Circuit Breaker. An instantaneous trip circuit breaker that is part of a listed combination motor controller.

 

[Jraef]

In reality there are lots of thermal mag breakers out there now with adjustable mag trips and the cost is basically the same as a mag-only breaker, so there is no reason not to just use them. Mag-only breakers are only cheaper in high volume, like for the factory combo starters.

 

[victor.cherkashi]

Don't forget, most of manufacturers label their equipment with MOP. According to NEC you must follow manufacturers instructions.

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