MCC Feeder Buckets- Trip settings

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adityalagudu

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victoria,TX,USA
I need to install dual pole 12" feeder buckets for Eaton Freedom 2100 series MCC. The motors ratings are : 480V, 0.5 HP, 6.6 LRA.

The minimum circuit breaker trip ratings I can see in the Eaton/ Cutler-Hammer feeder units catalog is 15A. Does all Circuit Breakers comes with adjustable trip settings?How to make sure the correct trip rating on the Breaker? If adjustable trip settings CB is required, how to order the correct Circuit Breakers.
 
adityalagudu said:
I need to install dual pole 12" feeder buckets for Eaton Freedom 2100 series MCC. The motors ratings are : 480V, 0.5 HP, 6.6 LRA.

The minimum circuit breaker trip ratings I can see in the Eaton/ Cutler-Hammer feeder units catalog is 15A. Does all Circuit Breakers comes with adjustable trip settings?How to make sure the correct trip rating on the Breaker? If adjustable trip settings CB is required, how to order the correct Circuit Breakers.
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The does not require you to have a circuit breaker with a rating less than 15 Amp so why would you bother?
 
A feeder breaker is there to protect the field wiring. Minimum field wiring is 14ga, which you protect with a 15A breaker. Therefore there is no need for a feeder breaker smaller than 15A.

When protecting small motors where the normal rules for minimum breaker sizes would result in 15A appearing to be too large, there are exceptions to allow you to do this. You have to understand all of the details. In a nutshell though, Fractional HP motors like your often have built-in thermal protection, which is one of those allowable exceptions. If not, you must have external thermal OL protection in some form or another and that is what protects the motor windings, leaving the Feeder CB there to just protect the 14ga conductors.

Standard Thermal-Magnetic Circuit breakers in North America are not adjustable, they are fixed trip. You can get Electronic Trip circuit breakers that are adjustable, but ones that have adjustments that go lower than 15A are few and far between, and comparatively very expensive if you find one.
 
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ptonsparky said:
You may have seen motor circuit protectors with adjustable trip ratings. They will be several times above your motor FLA to accommodate starting. Set them too low and they trip. Imagine that. Little or no time delay.
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And you can't use an MCP as a stand-alone feeder breaker, it can ONLY be part of a listed combination starter assembly.
 
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