# Residential Load Calc's Std vs Optional



## MechanicalDVR (Dec 29, 2007)

I almost hate to ask but what is the optional method?


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## KPE (Feb 7, 2017)

NEC 220.80...
C'mon man, I'm new here!


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## Drsparky14 (Oct 22, 2016)

KPE said:


> I have completed a load calculation for a customer, and there is a large difference between the minimum required service under the two different methods. He has a 200 Amp rated panel with a 175 A main breaker. We are trying to figure out if it will be possible to add two 50 amp circuits to his existing panel for two EVSE chargers. My standard load calc comes out to 143 Amps minimum service and optional method comes out to 106 amp both without including the new EVSE circuits. I can add two 50 amp circuits under the optional method and be below 175 Amps total but only one 40 Amp circuit under the standard method. Long story short, is there a problem using the optional method and adding the two EVSE circuits? It is a residential single family home with a 120/240v, 3 wire service over 100 Amps.
> 
> Both the standard calculation and the optional calculation can be used. I almost always just do the optional because 9/10 times I can load the panel up more.
> 
> ...


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