100A Subpanel

[Sandlamb]

I don’t understand why we can’t use #2 AL to feed a 100A subpanel but we can use it to run a 100A service. Can’t find 1 nor 1/0 quadruplex around me nor can I find a 90A breaker! Will 100 be ok?


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[infinity]

You need a conductor that's rated for at least 100 amps for a sub-panel. Service conductors have a diversity factor so they only need to be 83% of the OCPD size. #1/0 SER cable is a stock item around here.

Welcome to the Forum.

 

[Sandlamb]

This is going to be directly buried for 100’ to a pole barn for lights and receptacles.


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[wwhitney]

I don’t understand why we can’t use #2 AL to feed a 100A subpanel but we can use it to run a 100A service.

You can use #2 Al to feed a 100A subpanel if it's on a 100A residential service. But you can't do so on a larger residential service, because you only are allowed the 83% factor for a collection of loads with the full diversity of a dwelling unit.

Can’t find 1 nor 1/0 quadruplex around me nor can I find a 90A breaker! Will 100 be ok?

If the service size is above 100A, no, it won't be OK. Find larger conductors or a smaller breaker.

Cheers, Wayne