# NEC 2017 question: Can a demand factor be used for Air-Conditioner and EV charger of an existing residential load calculation?



## Fandi (Aug 16, 2021)

Hello All,

There’s an existing residence with existing A/C. The EV charger is new. An applicant uses a demand factor in section 220.83(A) for both the existing A/C and the new EV charger as he claims that both A/C and EV charger meet the description of 220.83(A)((3)(a): _'All appliances that are fastened in place, permanently connected, or located to be on a specific circuit_'.



To me, if there were no dedicated articles of the A/C and EV chargers, then the applying of the demand factor mentioned above is acceptable. But NEC 2017 actually have such dedicated articles (art. 440 for A/C and art. 625 for EV chargers) so we must look for demand factors in those sections. And if there are no demand factors in those articles then A/C and EV chargers shall be calculated at 100%. Moreover, per 625.42, EV chargers are continuous loads. Doesn’t it mean the EV charger load is 125% in the load calculation? The applicant might use automatic load management system to set the maximum load but my point is that he can’t automatically apply the demand factor in 220.83 (A) for the EV charger without the use of automatic load management system.



For using demand factor for A/C, I don’t see any demand factor in Article 440. Plus, per section 220.14 (A), I don’t see A/C is listed in 220.14(B) through (L).

Section 220.14 (A) states that

*(A) Specific Appliances or Loads. *An outlet for a specific

appliance or other load not covered in 220.14(B) through (L)

*shall be calculated based on the ampere rating of the appliance

or load served*.



Can you advise which is the correct way to calculate the unit load in this situation?



Thank you so much.


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## Beniah Naylor (Aug 16, 2021)

I think you are correct, simply because the house and A/C unit are existing, and the EV charger is new. Since the EV charger is not existing, and the title of 220.83 specifically says "Existing buildings", you calculate the house and A/C unit by 220.83, then you add the value for a new EV system to that number.


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## Paul Sweet (Aug 16, 2021)

I'm lazy.  I've always used the optional calculation of 220.82.


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