Sizing Feeder coming off a bus plug.

[Bwear]

I am an apprentice and wanting to better understand how sizing a feeder from a bus plug works. Say I have an equipment power panel with a 30A Main Circuit Breaker. Assuming continuous duty, do I multiply the 30A x 125%. Which comes out to 37.5A Would you fuse the Bus Plug at 40A and pull #8 THHN to it?

 

[infinity]

Yes your calculation (30*125%) is correct for a continuous load. Not sure what you mean by a bus plug, do you mean a circuit beaker?

 

[Bwear]

The Bus Plug is just a fusible safety disconnect coming off a Bus Duct or Bussway.

 

[david luchini]

If your panel has a 30A main circuit breaker, provide a 30A feeder. Fuse the bus plug at 30A, pull #10.

 

[infinity]

If your panel has a 30A main circuit breaker, provide a 30A feeder. Fuse the bus plug at 30A, pull #10.

Yes that's correct, my previous response seems to imply that you need a larger than 30 amp feeder but you do not.