EV charging calculated loads - opinions wanted

[jaggedben]

I have an AHJ who is saying that to calculate a service load according to article 220.83(A) one does not get to consider EV charging circuits to be part of the general load, but must add them at 125% (for being continuous) to the other load calculations. The AHJ seems to be specially calling out EVs as different.

In other words, instead of:
100% of the first 8kVA
+
40% of the remaining kVA

he wants:
100% of the first 8kVA of non-EV loads
+
40% of the remaining non-EV loads
+
125% of the EV loads

I can't find any language in the code that supports the AHJ's position. Am I missing something? I found some other threads on the subject but none of them for me nail down either:
a) whether the code treats EVs as special
b) what an EV really needs

Related question: 220.83 does not seem to require continuous load factors to be added (i.e. 125%). Am I missing something there?

See:
http://forums.mikeholt.com/showthread.php?t=175424
http://forums.mikeholt.com/showthread.php?t=145716
http://forums.mikeholt.com/showthread.php?t=160958

The situation pertains to an underground service that a customer would prefer not to pay to upgrade. It is currently a 125A main with two 40A car charging circuits, only one of which is currently being used. It does not have any air conditioning; only oven and dryer are electric among heating appliances. The calculated load under my reading of 220.83(A) is 98A whereas by the AHJs reckoning it's 166A. (I suppose perhaps I could convince the customer to have one car charging circuit removed and it would come to 116A by the AHJs reckoning.)

Thoughts? Please distinguish between how you think the code language does treat EVs vs if you have opinions about how it ought to.

 

[wwhitney]

What year NEC is operative?

Cheers, Wayne

 

[wwhitney]

I'm not so familiar with Article 220, but here are my thoughts:

- In the optional calculation method of section (2011) 220.82, an EVSE and EV would definitely fall under 220.82(B)(3)(a). As such, it is part of the 10 kVA plus 40% calculation. [Note: I sort of think an EVSE is not an appliance, as it is not utilization equipment, as it is just a fancy safety switch. But then the EV itself is the utilization equipment, and an appliance, and subject to 220.82(B)(3)(a). The only difference this would make is when the EVSE's rating exceeds the EV's rating (e.g. a 32 amp EVSE with a 27.5 amp EV, like the Nissan Leaf).]

- I check 2011 Table 220.3 "Additional Load Calculation References", and there is no reference to Article 625. I also couldn't find any reference to EVSEs in Article 220, so nothing modifies the basic argument of the first point.

- In 2014, Table 220.3 does refer one to 625.41. The relevant language from 625.41 is "Where an automatic load management system is used, the maximum electric vehicle supply equipment load on a service and feeder shall be the maximum load permitted by the automatic load management system." It seems to me that absent an automatic load management system, this doesn't change any of the above reasoning.

- From a practical point of view, allowing the 40% factor of 220.82 makes no sense for an EVSE. An EVSE is unique among residential outlets in that it can easily draw its full rated current for 8 hours or more in normal operations. [E.g. a 32 amp EVSE charging a 60 to 100 kWh EV.] With 3 or 4 EVSEs on a residential service, you could easily come up with a 220.82 calculation that is lower than the actual current demand of the EVSEs if all are in full use at once. So while the NEC doesn't seem to treat EVSEs specially under 220.82, it should; they belong outside the "General Loads" category of 220.82(B) and should be treated the same as the HVAC load under 220.82(C).

Cheers, Wayne