2023 EVSE Load Calculation

[T. Michael Rearic]

Hi guys,
I'm reading my shiny new code book and have come across a question. Does the 2023 NEC require us to include a 7200 VA load in our new residential service calculations and if so, why isn't it reflected in the Examples section?

 

[wwhitney]

If you are doing a standard calculation, and there is an EVSE, then yes, 220.57 requires the use of 7200 VA or the nameplate rating, whichever is larger. If you are doing the optional calculation any EVSEs would fall under 220.82(B).

Since the optional calculation is only for the service or main feeder, any feeder carrying less than the total connected load that supplies an EVSE will need to use the standard calculation and 220.57 would apply.

Cheers, Wayne

 

[T. Michael Rearic]

If you are doing a standard calculation, and there is an EVSE, then yes, 220.57 requires the use of 7200 VA or the nameplate rating, whichever is larger. If you are doing the optional calculation any EVSEs would fall under 220.82(B).

Since the optional calculation is only for the service or main feeder, any feeder carrying less than the total connected load that supplies an EVSE will need to use the standard calculation and 220.57 would apply.

Cheers, Wayne

Thanks Wayne. I guess I was thinking the code was making this mandatory like small appl. load. So, the 7200 wall load would be subject to the optional 40% reduction factor?

 

[wwhitney]

Thanks Wayne. I guess I was thinking the code was making this mandatory like small appl. load.

220.82(B)(2) specifically calls out 1500 VA for each SABC in the optional load calc, but 220.82 has nothing comparable for EVSEs.

So, the 7200 wall load would be subject to the optional 40% reduction factor?

By the direct wording of the NEC, yes, if you are installing a 30A 240V EVSE. 220.82 always uses the nameplate rating.

Now some AHJs find this implausible, since an EVSE may actually draw its nameplate current for well over 3 hours. So some AHJs may be requiring that it be included at 100% in the optional calculation. If the AHJ has adopted an official amendment to their electrical code, that's obviously fine to enforce. But I would say that absent an amendment, the wording of 220.82 doesn't provide any wiggle room for the AHJ to use their judgement and discretion to require a 100% factor for EVSEs in the optional load calculation. AHJs may disagree. : - )

Cheers, Wayne