How is EV charger load calculated in the 2023 NEC?

NEC 220.57 uses 7200 volt amperes or the EVSE nameplate rating, whichever is larger. Section 625.41 treats EVSE as a continuous load, so the circuit and overcurrent device are sized at 125 percent of the rated load.

Can load management let a big charger fit a small service?

Yes. NEC 625.42 permits the EVSE rating to be based on a restricted access adjustable setting or an energy management system, and Article 750 allows an EMS to limit the load so the service calculation stays within the conductor ampacity.

What size EV charger usually fits a 100 amp service?

A 40 ampere circuit at 32 amperes continuous is the common fit on a 100 ampere dwelling service, and 30 amperes is safer with electric range and dryer loads. Always confirm with a 220.83 calculation.

Can a 60 amp EV charger go on a 100 amp panel?

Sometimes, but the panel bus rating is not what decides it. The load calculation decides it, and on a 100 ampere service a 60 ampere charger usually fails a straight calculation. The 2023 NEC gives you two legitimate ways forward: run the numbers and prove there is room, or install load management so the charger cannot compete with the rest of the house.

Run the calculation first

Section 220.57 of the 2023 NEC sets the electric vehicle supply equipment load at 7200 volt amperes or the nameplate rating of the EVSE, whichever is larger. Section 625.41 classifies EVSE as a continuous load, so the branch circuit and the overcurrent device are sized at 125 percent of the rated load. A 60 ampere breaker corresponds to a 48 ampere continuous charger, which is 11,520 volt amperes at 240 volts.

For an existing dwelling, 220.83 is the practical tool. Part (B) applies when additional air conditioning or space heating is not being added, and it lets you take the first 8 kVA of the total connected load at 100 percent and the remainder at 40 percent, then add the larger of the heating or cooling load at 100 percent. Add the 11,520 volt ampere charger to the general lighting, small appliance, laundry, range, dryer, and water heater loads and see where you land. Divide the result by 240 volts and compare to 100 amperes.

Most 100 ampere services with an electric range and an electric dryer do not have 48 amperes of continuous headroom. A 40 ampere charger at 32 amperes continuous, or a 30 ampere charger at 24 amperes, frequently does fit.

Load management is the code sanctioned shortcut

Section 625.42 allows the EVSE rating to be based on an adjustable setting when the equipment has a restricted access adjustable setting, and it permits the use of an energy management system per 750.30 to limit the EVSE load. Article 750 lets an EMS set the maximum load on a feeder or service so the calculated load never exceeds the ampacity of the conductors or the rating of the overcurrent device.

In practice this means a charger with a listed load management module, or a separate EVEMS device that sheds the charger when the rest of the house draws too much. With that in place, a 60 ampere circuit can be installed on a 100 ampere service because the system is prevented from ever adding the full 48 amperes on top of peak house load. Section 750.30(C) requires the EMS to have an overriding means, and the setting must be documented and marked at the equipment.

The panel itself

Separately from the calculation, check the panelboard. Section 408.36 requires a panelboard to be protected by an overcurrent device not greater than its rating, and 408.30 requires the busbar rating to be adequate. You also need two adjacent spaces for the two pole breaker, and the breaker must be listed for the panel per 110.3(B). Section 625.40 requires the EVSE branch circuit to have no other outlets, and 210.8(A) and 625.54 drive GFCI protection where receptacle outlets are involved.

Field takeaway

Do the 220.83 calculation before you quote the job. If it does not fit, offer a 40 ampere charger, a load management system under 625.42 and Article 750, or a service upgrade. Do not simply install the 60 ampere breaker because there are two open spaces in the panel.