Sub Panel

[SparksRFlyin]

Where do you find in the NEC about what the max allowable amperage is to pull from an existing panel if panel is full (100A panel):-?

 

[augie47]

sub panel can be any size as long as it and it's feed are properly protected.

 

[kwired]

It is a 100 amp panel so you can use 100 amps branched out in an unlimited number of circuits.

 

[mcclary's electrical]

It is a 100 amp panel so you can use 100 amps branched out in an unlimited number of circuits.

Provided you stay within your load calcs for the service, yes.

 

[jaylectricity]

Provided you stay within your load calcs for the service, yes.

After the fact? Service feeders are already sized and protected.

 

[mxslick]

After the fact? Service feeders are already sized and protected.

Then new calcs are needed to make sure the added load doesn't exceed what the service can safely provide to avoid nuisance trips and worse....

SparksRFlyin, welcome to the forum!!

 

[hardworkingstiff]

After the fact? Service feeders are already sized and protected.

The service feeders should have the load calculations for the sub panel figured into them. If you are adding a sub panel "after the fact", the proper way to do it is to do a load calculation for the building, and if there is ampacity available on the main service feeder and panel size, then you can add your sub panel and additional loads only to the amount of the spare capacity in the main service.

I have seen the AHJ allow the PoCo information to be used in lieu of a load calculation if the meter records the maximum load it sees.

 

[mcclary's electrical]

After the fact? Service feeders are already sized and protected.

True, but they may not be big enough for the subpanel added load. Hence the load calc is needed.

 

[SparksRFlyin]

Thanks Fellas, I though that there was an easier way maybe a short cut like a rule of thumb in figuring out how much draw I could pull from a panel rather than do a full load calc.