CB sizing greater than 800A, 240.4(c)

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plevymcs

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I have a Service Entrance with conductors sized for a 1500A. The load is multiple motors in a MCC. I want to use a PD frame size CB, thermal-magnetic breaker. Am I allowed to round up to 1600A for overcurrent protection, or do I use the next lower size available setting? The MCC bus is 1600A so the 1600CB size would not exceed the bus ampacity.

If I am allowed to round up, does the conductor ampacity need to be increased so it is greater than CB setting?

If I have a Thermal-Magnetic breaker, similar to Siemens SPD, and it is located in a manner that meets the requirements allowing an adjustable setting CB, do I set it for 1500A and call it a day?

Paul
 
Since you're over the 800 amp threshold you can not round up. Sizing the OCPD to 1500 or less is required. This can be accomplished with a variable trip CB if all the conditions for its use are met.
 
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