Mike Holt's Electrical Toolbox app doing dwelling load calcs wrong?

[MNSparky]

Had a discussion with an AHJ about a dwelling service calc I did to confirm that we could put an EVSE in and he questioned where the EVSE was imputed in the calculation. I use Mike Holt's Electrical Toolbox app to do service calcs (optional method) because it's fast and easy but I think it may be wrong when adding an EVSE. Once we dug into it we discovered the app adds the EVSE as a fixed in place appliance and applies the demand factor to it. Both the AHJ and I feel that it should be added at the bottom of the calc at 100% of the product rating (2023 NEC 625.42) with no demand factor applied. Is the app wrong or are we missing something?

 

[brycenesbitt]

You can also use EVLMS. What's your setup?
Note:

220.53 Appliance Load ....This demand factor shall not apply to the following:
(1) Household electric cooking equipment that is fastened in place
(2) Clothes dryers
(3) Space heating equipment
(4) Air-conditioning equipment
(5) Electric vehicle supply equipment (EVSE)

220.57 Electric Vehicle Supply Equipment (EVSE) Load.
The EVSE load shall be calculated at either 7200 watts (volt-amperes) or the nameplate rating of the equipment, whichever is larger.

 

[texie]

Is the app based on the 2023 NEC? I ask because prior editions were silent on this. As noted by the above poster, new to the 2023 edition is 220.57 which requires EVSE to be calculated at the full value.

 

[texie]

I just checked my phone and I have this app. There is a setting to select code year and the latest is NEC 2017. That would explain your miscalculation. There does not seem to be an updated version of the app so I'm left wondering if mike has abandoned this app. Yet it is shown on his website as current. This seems so unlike him. May have to reach out to see whats up with this.

 

[JoeStillman]

You can use the optional method. See 220.82(B)(3).

 

[MNSparky]

I just checked my phone and I have this app. There is a setting to select code year and the latest is NEC 2017. That would explain your miscalculation. There does not seem to be an updated version of the app so I'm left wondering if mike has abandoned this app. Yet it is shown on his website as current. This seems so unlike him. May have to reach out to see whats up with this.

Where do you see the setting for the NEC version? The only settings it offers me is language, measurement units and temperature units. I deleted the app and reloaded to the latest version 1.0.34. I have a iPhone.

At any rate, we all agree that the EVSE needs to be taken at 100% at the bottom, right? If so I'll have to go back to doing the calcs manually until the app gets updated.

 

[MNSparky]

You can use the optional method. See 220.82(B)(3).

That's the method I've been using.

 

[wwhitney]

At any rate, we all agree that the EVSE needs to be taken at 100% at the bottom, right? If so I'll have to go back to doing the calcs manually until the app gets updated.

No, I don't agree, as far as what 220.82 actually says. I agree that would be a reasonable methodology for the NEC to adopt, but it hasn't done so.

Does your jurisdiction have an amendment to 2023 NEC 220.82? If not, EVSEs fall under 220.82(B), and are subject to the 40% marginal factor.

Cheers, Wayne

 

[MNSparky]

You can also use EVLMS. What's your setup?
Note:

220.53 Appliance Load ....This demand factor shall not apply to the following:
(1) Household electric cooking equipment that is fastened in place
(2) Clothes dryers
(3) Space heating equipment
(4) Air-conditioning equipment
(5) Electric vehicle supply equipment (EVSE)

220.57 Electric Vehicle Supply Equipment (EVSE) Load.
The EVSE load shall be calculated at either 7200 watts (volt-amperes) or the nameplate rating of the equipment, whichever is larger.

Dwelling with a 200amp service but they want to go all electric appliances along with a 100amp Ford Charge Station Pro. It's not going to happen without some kind of load shedding.

 

[MNSparky]

No, I don't agree, as far as what 220.82 actually says. I agree that would be a reasonable methodology for the NEC to adopt, but it hasn't done so.

Does your jurisdiction have an amendment to 2023 NEC 220.82? If not, EVSEs fall under 220.82(B), and are subject to the 40% marginal factor.

Cheers, Wayne

625.42 says its a continuous load and to size service/feeder in accordance with the product ratings... I take that as meaning we need to put it in at 100% when doing the calc but it's not very clear.

 

[wwhitney]

625.42 says its a continuous load and to size service/feeder in accordance with the product ratings... I take that as meaning we need to put it in at 100% when doing the calc but it's not very clear.

To me "size service in accordance with the product ratings" just means "put the product rating into the usual formulas." I.e. it's redundant language.

Cheers, Wayne

 

[MNSparky]

I emailed the Chief AHJ for MN so I could put this to bed. He said the EVSE should not be considered a fixed in place appliance and should not have the demand factor applied to it in 220.82(B)(3). Per 625.42, the EVSE should be entered at 100% of the equipment rating. He also mentioned this is consistent with proposed language for the 2026 NEC clarifying EVSE load calculations.

So, the Mike Holt app is either operating on a different code cycle (I still haven't found which one it's working under) or it has EVSE loads entered wrong, at least for MN.

 

[wwhitney]

I emailed the Chief AHJ for MN so I could put this to bed. He said the EVSE should not be considered a fixed in place appliance and should not have the demand factor applied to it in 220.82(B)(3). Per 625.42, the EVSE should be entered at 100% of the equipment rating.

He's applying reasonable judgement as to how the NEC should read, rather than going by what the NEC actually says. Reading 625.42 as modifying Article 220 to require a 100% factor for EVSEs in all cases is just not supported by the language. "100%" or the like doesn't appear anywhere in 625.42.

So I agree that the NEC should possibly be rewritten to eliminate the 40% factor for EVSEs under 220.82, but it hasn't happened yet.

Cheers, Wayne

 

[MNSparky]

He's applying reasonable judgement as to how the NEC should read, rather than going by what the NEC actually says. Reading 625.42 as modifying Article 220 to require a 100% factor for EVSEs in all cases is just not supported by the language. "100%" or the like doesn't appear anywhere in 625.42.

So I agree that the NEC should possibly be rewritten to eliminate the 40% factor for EVSEs under 220.82, but it hasn't happened yet.

Cheers, Wayne

I see your point and agree the language in the code definitely leaves it up to several possible interpretations. The language that pulled me towards it needing to be accounted for at 100% of the nameplate is how it's considered a continuous load and the language in 625.42 and 220.57 saying it needs to be calculated at the nameplate rating. Hopefully they clarify in the 2026 NEC. Thanks for the opinions!

 

[brycenesbitt]

Dwelling with a 200amp service but they want to go all electric appliances along with a 100amp Ford Charge Station Pro. It's not going to happen without some kind of load shedding.

Oooh, that's tough. AFIK the 100A ford charge station does not support load management.
You could do up to 60A charger with an RVE DCC-12 though.
A Channing Street Copper stove for the kitchen?

 

[Fred B]

Dwelling with a 200amp service but they want to go all electric appliances along with a 100amp Ford Charge Station Pro. It's not going to happen without some kind of load shedding.

Add to it that most of the ford vehicles that are looking for the 100A charge stations also provide potential to use as bi-directional charging acting as a power backup when utlity power is out. Would have to look further to see if any other conditions occur when used as such like when using a solar battery combo that back feed.

 

[retirede]

Add to it that most of the ford vehicles that are looking for the 100A charge stations also provide potential to use as bi-directional charging acting as a power backup when utlity power is out. Would have to look further to see if any other conditions occur when used as such like when using a solar battery combo that back feed.

The EVSE itself does not provide bidirectional charging. It simply has the ability to communicate with the truck to tell it to close the HV battery contactors and feed the DC to an external inverter. It takes an additional $5000 worth of equipment to make it work.