Residential Calculations

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xformer

Senior Member
Location
Dallas, Tx
Occupation
Master Electrician
Hello everyone. Question, For dwelling unit calculations, is an EVSE load required? My understanding is that it is required. Am I in error?
 
I don't think the NEC requires it, but other state codes may require it. The Illinois Electric Vehicle Charging Act requires dwelling units, up to four in a building, have service capacity and space for a 2 pole 40 amp breaker for EV charging equipment for each dwelling. I assume other states have similar rules.
 
I think that is new for the 2023 in the part III standard calc. I don't think it applies to any of the optional calcs.
 
don_resqcapt19 said:
Nothing in that section requires you to include an EV circuit. The section simply tells you how to calculate the load for an EV charger if you decide to install such a circuit.
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A requirement if op want to install evse like for a range 220.55
 
Deltaforce said:
A requirement if op want to install evse like for a range 220.55
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That has nothing to do with the original question. The question simply asks if the NEC requires you to include load for an EV charger. It does not. It simply tells us how to calculate such a load if you want to install an EV charger.

No idea of what 220.55 has to do with an EV circuit.
 
I think what deltaforce is saying and we all seem to agree, is in the NEC 220 calculations its a optional branch circuit and outlet like a range circuit and outlet is optional but they give you a default value if the equipment is not yet known.
So you can wire a new home with a 240V 50A outlet in the garage, and count the load as 7200VA if the EVSE is unknown at the time.
Unlike a HVAC branch circuit and outlet where an exact nameplate FLA / RLA needs to be known at the time of calculation to do a correct calculation, if I have a 30A disconnect (outlet) for a unknown HVAC load at time of calculation there is no default value provided by the NEC.
 
don_resqcapt19 said:
That has nothing to do with the original question. The question simply asks if the NEC requires you to include load for an EV charger. It does not. It simply tells us how to calculate such a load if you want to install an EV charger.

No idea of what 220.55 has to do with an EV circuit.
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You 100% correct, code not require evse load in dwelling load calculation just like it not require home range load in dwelling load calculation. However if op wants install evse, which of course not in his original question, evse load to include in dwelling unit calculations as per 220.57 just like if op want install a range he include range load in dwelling load calculations as per 220.55
Sorry if it incorrect or confusing
 
xformer said:
Hello everyone. Question, For dwelling unit calculations, is an EVSE load required? My understanding is that it is required. Am I in error?
Click to expand...
I calculate EVSE load at Zero VA.

Now true, in the 2026 load calculation we got the wording tweaked to allow either the nameplate of the EVSE or 7200VA if the EVSE is unknown. But it's better at zero, which just requires installing equipment to ensure the EVSE is either non-coincident, or dynamically limited. There's really no need to add any capacity for residential EV charging: there's tons of spare capacity as long as you avoid certain peak times of day using dynamic techniques.
 
I see these EV questions and threads a lot. Nobody is first looking into seeing if the primary transformer can handle the load. This is the first thing to look into before assuming or adding a bunch of EV circuits. There was a transformer fire in an apartment building complex after they added a bunch of EV outlets in Florida a few months ago.
 
herding_cats said:
I see these EV questions and threads a lot. Nobody is first looking into seeing if the primary transformer can handle the load. This is the first thing to look into before assuming or adding a bunch of EV circuits.
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The utilities are bad at their part of that.
Yes, they want the load data to determine if the secondaries can handle it.

But in my area they assume the EV load will be at maximum at 6pm when the rest of the load is at peak and THAT is an invalid assumption.
Right now my most local Poco's forms are not complex enough to model real EV loads.

The Pocos don't share the secondary and transformer loads willingly in my areas: they reserve the exclusive right to size them.
So nobody can "check" they have to go through a multi-week and highly variable process for a new load directly with an insane bureaucracy.
 
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