Breaker sizing

[Rockyd]

Working for a contractor who wants to put a 1/0 Al wire on a 70 amp siemens breaker. Wire is already pulled. I don't think it will happen, (can anyone confirm max wire size to breaker size for siemens) short of a special order from the factory.

The 70A breaker is the main for hundereds of sub-panels in a high end project, so if special order is only way, they can do that.

Haven't seen any of the panels, but believe it is a bolt on breaker with 125 amp bus bars. Think it would be cheaper to just install 100 amp breakers, but that is a whole different issue.

 

[Minuteman]

Why not splice to a #4 copper in a listed AL/CU connection?

 

[kingpb]

I think you will find that the terminals can take the #1/0 AWG AL. It is probably the upper limit, but should work. Not sure why the #1/0 AWG, but if it's for voltage drop, you can always use pins crimped onto the cable at the terminals, which will reduce the size into the lugs, actually may be a good practice anyway because AL terminations require maintenance (which rarely gets done).

 

[Rockyd]

Thanks King! Without having a chance to inspect the equipment, it didn't sound right that the breaker may, or may not, accept a 1/0 wire. 110.3(b) should list the Max size wire, but by the time I get to look at it, it's too late.

Splicing is going to be out of the question....sometimes, what happens in Vegas, needs to stay in Vegas!