Control panel circuit protection

[althomas49]

When designing a control panel that will contain a 100HP soft start, a 10HP IEC contactor, and the associated motor control circuit, how does the main panel disconnect get applied?

I understand that I need a main panel circuit breaker, a circuit breaker for 100HP, a circuit breaker for the 10HP, and a circuit breaker for the control circuit. In this case though, since the 100HP starter requires such a large CB, the main panel CB would be the same size, so do I actually need 2 of the same size CB or can I connect the smaller CBs on the load side of the large CB?

 

[DRWeig]

If your main panel breaker also provides the code-required protection for entire panel, and it also is the proper size for the 100 HP motor and its soft-starter, you don't need a second one for that specific load.

If you've done the calculations independently (for main breaker and 100 HP breaker) and arrived at the same answer, you are good to go. Just feed the 10 HP and control circuit loads through their own independent protective devices.

Good on ya,

Goober Dave

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