Motor Starter used as a circuit breaker?

[gadero]

End user is trying to minimize project cost and has a spare starter in an MCC that he wants to reuse and serve a piece of packaged mechanical (multiple motors) equipment. The equipment is equipped with an integral control panel that protects the motors. The starter would protect the feeder only. The starter includes a motor circuit protector and thermal overload element.

I've never seen this application and not sure that I may have a problem. Any thougths?

Thanks

 

[tommom]

It's not listed for the application - I wouldn't do it. That starter is sized for a motor circuit, which is sized under different code and UL rules. I don't think it should be done.

 

[dpc]

Not allowed. A combination starter is listed for control and protection of one motor. Just replace the MCP with a standard thermal-mag breaker, get rid of the starter and O/L and use that instead.

 

[waross]

Many motor starters start life as a contactor and then an overload devicer is added.
As dpc says you must change the MCP and remove the overload relay. The starter/contactor may have a rating as a contactor that will allow it to be used as a switching device if that is dsirable.
Some of the magnetic motor starters that I purchase are a combination of a contactor with NEMA motor ratings, IEC motor ratings and additional ratings for use as a contactor,
And an overload relay, priced and sold separately.
respectfully

 

[rcw retired EE]

Technically this can be done, but not according to code. The motor circuit protector provides short circuit protection and the starter overloads could be sized to protect the feeder cables from overload. But since the equipment is not listed for such a service I would not recommend it. Too much liability if something is not correct or someone changes the overload settings.

 

[waross]

I apologize for an unclear post.
I was following (and agreeing with) dpcs post. I meant to add that after proper overload and over current protection was installed, the starter could be used as a contactor if there was a wish to control the circuit remotely.
This would be contingent on the contactor haveing an adequate current rating when used as a contactor.
respectfully