# Installing a Sub Panel



## jhayleck (Mar 19, 2012)

I have a quick questions about installing a sub panel. I bought a house that had a sub panel being feed from the main panel with a 100 amp 2 pole breaker and the sub panel itself had a 100 amp breaker, Is this aloud? code and where in the code book would this be found. 

Thank you

Rookie electrician


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## Dennis Alwon (May 9, 2009)

It is all based on the loads being served. There is no reason that you cannot do that as long as the load on the main is not over 100 amps. You can have 6 panels rated 100 amp and fed with 2 pole 100 amp breakers as long as the calculated load is not greater than the service.


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## k_buz (Mar 12, 2012)

What size wire is feeding the subpanel?


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## Cletis (Aug 20, 2010)

*90*



k_buz said:


> What size wire is feeding the subpanel?


I hope their 90's ...


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## bobelectric (Feb 24, 2007)

We are allowed to use a subpanel at 80% of mcb value.


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## MHElectric (Oct 14, 2011)

bobelectric said:


> We are allowed to use a subpanel at 80% of mcb value.


Thats interesting.. there any code reference for this, or is this just what is enforced in your area. Ive always figured inspectors would frown on anything over 50%, but thats just me playing it safe.


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## BBQ (Nov 16, 2010)

The NEC allows a 400 amp sub panel from a 60 amp service 

As Dennis said the only factor is the actual load.


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## wildleg (Apr 12, 2009)

BBQ said:


> The NEC allows a 400 amp sub panel from a 60 amp service
> 
> As Dennis said the only factor is the actual load.


 
how do you come up with the number 400 ?


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## BBQ (Nov 16, 2010)

wildleg said:


> how do you come up with the number 400 ?


They taught me my numbers in school. 


It was just a number, it could have been a 4000 amp sub panel from a 30 amp service but that seemed stupid :laughing:


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