Proposed alteration to NEC 120.57 : Load Calcs for EVSE

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brycenesbitt

Senior Member
Location
United States
Comments? Angry letters?
The following is the text of a proposed adjustment to the text of NEC120.57, which is under revision for the 2026 NEC cycle with comment due August 28th 2024:

Right now if you have a low power L2 EVSE, you have to load calculate it at 7200 Watts regardless.
If you had many such L2 chargers that would result in a vast overstatement of the necessary power.:

CURRENT SECOND DRAFT
120.57 Electric Vehicle Supply Equipment (EVSE) Load.
The EVSE loads shall be calculated at either 7200 watts (volt-amperes) or the nameplate rating of the equipment, whichever is larger, for each EVSE served, unless modified by 625.42.
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PROPOSED DRAFT
120.57 Electric Vehicle Supply Equipment (EVSE) Load.
For each EVSE served, loads shall be calculated at the 80% of the capacity of the attached receptacle, the nameplate rating for fixed equipment, or the adjusted nameplate rating for fixed equipment derated and labeled per 625.42(A). Disconnected circuits reserved for future EVSE shall be calculated at 7200 watts (volt-amperes). Circuits load managed per 625.42(B) may be calculated down to 0 watts, per the equipment capability.
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This input will be 1753-NFPA 70-2024, but I'm don't own the copyright to share it with the forum :-(.
It can be edited until the deadline.
 
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brycenesbitt

Senior Member
Location
United States
I was just told the NEC style manual won't allow paraphrasing another section of code as in
"fixed equipment derated and labeled per 625.42(A)".
Ugh. Any tips on how to reword?
 
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wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
So, in the first draft report, 625.42(A) says "All EMS used to provide load management of EVSE shall comply with 130.30, and the maximum equipment load on a service, feeder, and branch circuit shall be the maximum load permitted by the EMS." As Chapter 6 is allowed to amend Chapters 1 through 4, the second part of that sentence effectively amends 120.57. Therefore I don't think 120.57 needs to reference 625.42(A).

625.42(B) (EVSE with Adjustable Settings) doesn't have any comparable language, like "the equipment load shall be limited to the adjusted current setting." One approach would be to add that language in 625.42(B), rather than amending 120.57

That would effectively leave 120.57 as just a default. It would still mean that a fixed setting 20A only EVSE would need to be calculated at 7200VA, which is clearly unreasonable. So amending 120.57 is a more direct approach.

Seems like 120.57 should just say "use the nameplate rating, or 7200 VA when that information is not available."

Cheers, Wayne
 
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