EV chargers, Article 220.83, Article 310.12, another residential idiot arguing with the AHJ!

[thescooper]

All info below relates to the 2020 NEC
A relatively new inspector in a town that I don't do a lot of work in requested a service load calculation for a new EV charger install I gave a quote for. It is an existing single family dwelling unit, with a 200 amp CHTH main breaker panel fed with 4/0 aluminum SEU, and the customer wants a 48 amp Tesla Wall Connector installed.
I performed a load calculation using article 220.83, and the load came out to 138 amps. The inspector refuses to approve the permit, because when he performed a standard load calculation, it came out to 194 amps, which is both a large discrepancy from the optional method, and also above the rated ampacity of 4/0 aluminum according to 310.16.
I argued that 220.83 is a valid method to determine whether an existing service is capable of handling an increased load, which he argued it was not (and then later backtracked), and also said that 310.12 does not say anything about the calculated load, only the size of the service equipment.
Am I crazy? Am I interpreting article 310.12 incorrectly? Is the AHJ allowed to pick and choose which load calculation method is acceptable or not? He wants me to install 250kcmil aluminum service entrance conductors (based on his unprompted load calculation) before he will approve my permit. Let me know what you guys think.

 

[jaggedben]

You are not crazy. He is green.

For a maybe helpful or maybe not discussion of 310.12 see here:

What Exactly Is The "Service Rating"?

I've found a befuddling little wormhole. 310.12 states: For a service rated 100 amperes through 400 amperes, the service conductors supplying the entire load associated with a one-family dwelling, or the service conductors supplying the entire load associated with an individual dwelling unit...

forums.mikeholt.com

 

[Elect117]

Is the EV charger considered an appliance? Should it be added separately? It doesn't fit into a,b,c, or d.

I agree that the inspector is wrong on being able to use the optional method. I just wonder if special equipment fit into the 40% reduction applied to appliances.

EV chargers & residential load calcs

Looking around online, I was surprised that the city of San Ramon CA has a 125% rating on EVSE equipment...

forums.mikeholt.com

I think it was a grey area on whether or not the optional method is just that. Optional and permissive and applies to only the loads listed in the calculation method.

NEC 2023 - 220.40 - "
220.40 General.
"The calculated load of a feeder or service shall not be less than the sum of the loads on the branch circuits supplied, as determined by Part II of this article, after any applicable demand factors permitted by Part III or IV or required by Part V have been applied."

Does the 4/0 still work if you separate that and add in the 125% * 48A to the mix?

 

[tortuga]

An EVSE is not a charger, appliance or an outlet its 'equipment' that provides a function similar to a GFCI to protect a 'pendant cord' type receptacle outlet.
That receptacle outlet happens to be a configuration for charging electric vehicles and connects to the vehicle.

 

[retirede]

An EVSE is not a charger, appliance or an outlet its 'equipment' that provides a function similar to a GFCI to protect a 'pendant cord' type receptacle outlet.
That receptacle outlet happens to be a configuration for charging electric vehicles and connects to the vehicle.

But it also determines the maximum possible charging current for its branch circuit. That load has to accounted for in the calculation somewhere.

 

[Elect117]

But it also determines the maximum possible charging current for its branch circuit. That load has to accounted for in the calculation somewhere.

That is why I ask if it should be included in the optional method or calculated as additional.

Based on my reading of 220.40, I am leaning towards no. As in, you shouldn't include it in the 40% demand factor.

 

[wwhitney]

Based on my reading of 220.40, I am leaning towards no. As in, you shouldn't include it in the 40% demand factor.

220.40 is immaterial when applying 220.82, as 220.40 is in Part III, but 220.82(A) says its computation is "instead of the method specified in Part III".

So any EVSE contribution to the 220.82 calculation must be in one of the categories listed within 220.82. The only category that fits is 220.82(B), which gets the 40% demand factor.

This is arguably non-conservative, but for a single EVSE at a dwelling unit, not likely to overcome the safety factor from the over-conservativeness of the rest of the 220.82 calculation. For multiple large EVSEs at a dwelling unit, good judgement might require going larger than the 220.82 minimum size.

Note that one side effect of 220.82 omitting all of Part III is that 220.60 on non-coincident loads does not apply to the optional calculation. You need to include all the loads in the 220.82 calculation, This is slated to be fixed in the 2026 NEC, when 220.60 moves to Part I, 220.6.

Cheers, Wayne

 

[Fred B]

The use of an energy management system (EMS) in conjunction with the EV can allow for an EV in excess of the calculated max load to the structure. Essentially a load shed like used for Generator.

AFA the load calculation and the use of 4/0 or 250kcmil, if this is a dwelling unit it allows for an "undersized" 4/0 feeder @ 200A, AL per 310.12(A) Table, and not the 180A per table 310.15(B)(16) 0r 310.16.

 

[thescooper]

Thanks for all the replies so far guys. This is how I interpret the code (2020 NEC):
Article 220.83(A)(3)(a): All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
Article 100 definition of appliance: Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air-conditioning, food mixing, deep frying, and so forth.
Article 100 definition of utilization equipment: Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
So I'd argue that an EV charger (hardwired) fits the criteria to fall under article 220.83(A)(3)(a), because it's an appliance that's fastened in place, which would make it subject to the 40% demand factor afforded by 220.83.
I'd also argue that I do not have to include the 125% demand factor required by article 625.41 because article 220.83 only requires adding the nameplate rating of the appliance.
I know that article 230.42(A)(1) requires that the service entrance conductors be sized to handle the continuous and noncontinuous loads, but if you read article 230.79, it states:
The service disconnecting means shall have a rating not less than the calculated load to be carried, determined in accordance with Part III, IV, or V of Article 220, as applicable.
So article 230.79 determines my service size according to 220.83 (which in this case is an existing 200 amp service), and article 310.12 determines my service entrance conductor size.
310.12 states: For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted to be sized in accordance with 310.12(A) through (D).
Nowhere does 310.12 have any exceptions, or say unless, etc. It only says if its a single family dwelling, 100-400amp, and there are no adjustment factors required, then use Table 310.12.
In summery, even if my calculated load exceeded the ampacity rating of the service entrance conductors (which according to my load calculation, it didn't exceed), I believe 310.12 allows me to continue to use existing 4/0 Al conductors. I believe you do not need to apply a continuous load demand factor to a load calculation for an EV charger (in this specific case) because article 220.83 literally states to use the nameplate rating. So I think I'm correct, and the inspector is looking for a reason to reject my permit, because it's not how he would have done it.

 

[jaggedben]

The use of an energy management system (EMS) in conjunction with the EV can allow for an EV in excess of the calculated max load to the structure. Essentially a load shed like used for Generator.

Do you have a code citation that explicitly permits that, and that overrides requirements to calculate the total load in accordance with 220?

 

[Fred B]

This also needs to be considered: 2020 reads essentially the same as the 23 here quoted.

625.41 Overcurrent Protection.
Overcurrent protection for feeders and branch circuits supplying EVSE and WPTE, including bidirectional EVSE and WPTE, shall be sized for continuous duty and shall have a current rating of not less than 125 percent of the maximum load of the equipment. Where noncontinuous loads are supplied from the same feeder, the overcurrent device shall have a current rating of not less than the sum of the noncontinuous loads plus 125 percent of the continuous loads.

Seems that highlighted section would include service feeders and breakers

625.42 Rating.
The EVSE shall have sufficient rating to supply the load served. Electric vehicle charging loads shall be considered to be continuous loads for the purposes of this article. Service and feeder shall be sized in accordance with the product ratings, unless the overall rating of the installation can be limited through controls as permitted by 625.42(A) or (B).

 

[jaggedben]

Thanks for all the replies so far guys. This is how I interpret the code (2020 NEC):
Article 220.83(A)(3)(a): All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
Article 100 definition of appliance: Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air-conditioning, food mixing, deep frying, and so forth.
Article 100 definition of utilization equipment: Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
So I'd argue that an EV charger (hardwired) fits the criteria to fall under article 220.83(A)(3)(a), because it's an appliance that's fastened in place, which would make it subject to the 40% demand factor afforded by 220.83.

Some of us would argue that the EVSE (it's not a charger) isn't an appliance because it doesn't perform any functions similar to those mentioned in the definition of an appliance; those functions are performed by the EV. And the EV isn't fastened in place, although one could argue it's located to be on a specific circuit. Is the EV itself an appliance? Sounds weird to say but I think it meets the definition. It's still an interesting point to make that perhaps 220.82s antiquated language doesn't require one to include an EV load at all. But I don't think any of us would argue that it's right for EV loads to be left out load calculations. For that reason I continue to be surprised that 220 doesn't address EV loads explicitly.

I'd also argue that I do not have to include the 125% demand factor required by article 625.41 because article 220.83 only requires adding the nameplate rating of the appliance.

I think this is correct.

I know that article 230.42(A)(1) requires that the service entrance conductors be sized to handle the continuous and noncontinuous loads, but if you read article 230.79, it states:
The service disconnecting means shall have a rating not less than the calculated load to be carried, determined in accordance with Part III, IV, or V of Article 220, as applicable.
So article 230.79 determines my service size according to 220.83 (which in this case is an existing 200 amp service), and article 310.12 determines my service entrance conductor size.
310.12 states: For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted to be sized in accordance with 310.12(A) through (D).
Nowhere does 310.12 have any exceptions, or say unless, etc. It only says if its a single family dwelling, 100-400amp, and there are no adjustment factors required, then use Table 310.12.
In summery, even if my calculated load exceeded the ampacity rating of the service entrance conductors (which according to my load calculation, it didn't exceed), I believe 310.12 allows me to continue to use existing 4/0 Al conductors. I believe you do not need to apply a continuous load demand factor to a load calculation for an EV charger (in this specific case) because article 220.83 literally states to use the nameplate rating. So I think I'm correct, and the inspector is looking for a reason to reject my permit, because it's not how he would have done it.

I agree with your conclusions. Certainly the language in 310.12 is rather muddy, but this is how most people see it as far as I've ever seen. I've never had an AHJ question applying 310.12 based on breaker rating, when the calculated load is below the breaker rating.

 

[wwhitney]

Do you have a code citation that explicitly permits that, and that overrides requirements to calculate the total load in accordance with 220?

For EVSEs, 625.42(A) is new in the 2023 NEC. Which I believe added alot of other relevant sections, like an expanded 750.30(C) which references a new 220.70.

Cheers, Wayne

 

[Birken Vogt]

Do you have a code citation that explicitly permits that, and that overrides requirements to calculate the total load in accordance with 220?

For EVSEs, 625.42(A) is new in the 2023 NEC. Which I believe added alot of other relevant sections, like an expanded 750.30(C) which references a new 220.70.

Cheers, Wayne

It should also fall under "unlikely to be operated simultaneously" in the old wording

 

[ramsy]

How to calculate a new ESVE load is clear for existing buildings, regardless if not defined as an appliance.

220.16(A)(2)
Loads for new circuits or extended circuits in previously wired dwelling units shall be calculated in accordance with 220.14.

220.14(A) Specific Appliances or Loads.
An outlet for a specific appliance or other load not covered in 220.14(B) through (M) shall be calculated based on the ampere rating of the appliance or load served.

The operative terms "other load not covered", "or load served" in 220.14(A) wont be limited to appliances.

 

[ramsy]

do not have to include the 125% demand factor required by article 625.41 because article 220.83 only requires adding the nameplate rating of the appliance.

The operative terms "other load not covered", "or load served" in 220.14(A) wont be limited to appliances.

One reason for calculating ESVE loads @ 125% nameplate rating in Art. 220 is 625.42 rating "shall be considered to be continuous loads", and due to increased inductive current rise, since a significant inductive component exists with ESVE inverters + any wireless inductor..

 

[ramsy]

I argued that 220.83 is a valid method to determine whether an existing service is capable of handling an increased load, which he argued it was not (and then later backtracked), and also said that 310.12 does not say anything about the calculated load, only the size of the service equipment.

Your best argument may be getting a 220.87 load calc on a stamped set of plans, for lowest bid with this AHJ.

 

[Jpflex]

In regard to the service feeder being too small for the added load did this include the 83% ampacity reduction allowance?

 

[thescooper]

In regard to the service feeder being too small for the added load did this include the 83% ampacity reduction allowance?

The AHJ is stating that because he did a load calculation, and it came out to over the rated ampacity of 4/0 aluminum, that I have to replace the service entrance conductors, regardless of what 310.12 states.

 

[jaggedben]

The AHJ is stating that because he did a load calculation, and it came out to over the rated ampacity of 4/0 aluminum, that I have to replace the service entrance conductors, regardless of what 310.12 states.

I wouldn't try to win on that particular point because it's far from settled, see the discussion I linked to in post #2.

I would instead focus on being permitted to use 220 Part IV, which is quite clear. In your initial post you mentioned using 220.83, but perhaps with this inspector 220.82 is a better bet since it applies to all dwellings regardless of whether they are existing and such. Don't concede the point about 220.83, but just show him that you are compliant with 220.82 as well.