Sub-Panel Code Section?

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JOHNEO99

JOHNEO99

Senior Member
Location
Northern Illinois
Hi everyone

I am doing a house for a friend and he wants a sub-panel in his garage.
Ive done a hundred sub panels in houses usually 100a sub off 200a main.

My question is what section in the code book states what size sub panel can be drawn from the main panel?

What is the largest size sub panel you can bring off a 200 amp main?


J
 
Technically there is no such thing as a sub-panel, so you will ot find any NEC reference to one.

The code only addresses service entrance location equipment and non-service entrance location equipment.

Any panel can feed any number of additional panels at any ampacity that the original panel is designed to handle.

As an extreme example: a Square D QO124M150 panel has a 150A main breaker with 24 1-pole spaces, but you could feed (6) 200A 4 wire "sub-feed" panels (each 200 breaker takes 4 spaces and there are 12 spaces on each side of the bus) assuming the wire gutter capacity is not exceeded.
 
JOHNEO99 said:
What is the largest size sub panel you can bring off a 200 amp main?
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It?s not about the size of the sub-panel, nor about the number of available spaces in the main panel. It?s all about the load. Is there sufficient room in the existing service to add new load? If so, then you can put any size sub-panel you want, so long as you do not add more load than the service can handle.
 
charlie b said:

It?s not about the size of the sub-panel, nor about the number of available spaces in the main panel. It?s all about the load. Is there sufficient room in the existing service to add new load? If so, then you can put any size sub-panel you want, so long as you do not add more load than the service can handle.
Click to expand...


So i do a load calc to figure the load?
 
JOHNEO99 said:
So i do a load calc to figure the load?
Click to expand...
Or do a 30 day load reading, or get a year's worth of demand readings from the utility (showing peak demand in KW, not usage in KW-Hr). But I think a load calc is easier and faster, for a single family residence.
 
charlie b said:

Or do a 30 day load reading, or get a year's worth of demand readings from the utility (showing peak demand in KW, not usage in KW-Hr). But I think a load calc is easier and faster, for a single family residence.
Click to expand...

Ya its new so i will do the load calc and go from there.

Thank you
 
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