Main Breaker versus Main Lug

[Scott1186]

I have a 225 KVA transformer feeding a panel. The primary side of transformer has disconnecting means within 10 feet. The secondary side is feeding a distribution panel. There is a breaker there feeding a 42 circuit panel approximately 250 feet away in a separate room. Does that final panel need to be a main breaker or can it be main lug? I referenced 240.21 (c) (1-6), but am looking for a little more clarification.

 

[Buck Parrish]

Main Lug

 

[petersonra]

there is no reason the panel has to have a main. there is no code requirement that any panel have a main. it does have to be protected at its bus rating though, but the protection does not have to be within the panel.

 

[charlie b]

Let me ask for clarification on one point:

The secondary side is feeding a distribution panel.

Does this distribution panel have a main breaker? If not, then there needs to be an overcurrent device of some description between it and the transformer secondary. I agree that the "final panel" does not need a main breaker.

 

[ggunn]

there is no reason the panel has to have a main. there is no code requirement that any panel have a main. it does have to be protected at its bus rating though, but the protection does not have to be within the panel.

...at or below its bus rating...