Usually a 150-amp service has more headroom than a 100-amp service for a single Level 2 charger, but that is not a load calculation. You still add the charger to the existing calculated or measured load and compare the total with 150 amps.
A 150-amp service is a middle size that many explainers mention and then skip. It is not automatically comfortable, and it is not a 200-amp heavy-up.
| Step (2023-style optional method, educational) | Result |
|---|---|
| General lighting at 3 VA/ft² | 5,400 VA |
| Small-appliance and laundry circuits at 1,500 VA each | 4,500 VA |
| General load including listed nameplates and EVSE | 21,420 VA |
| First 10 kVA at 100%, remainder at 40% | 14,568 VA |
| Larger of the heating or cooling values entered, at 100% | 4,000 VA |
| Calculated load | 18,568 VA · 77.4 A at 240 V |
| Compared with this walk-through’s service rating | 77.4 A is under a 150 A rating by 72.6 A |
Educational walk-through of the optional dwelling-unit method structure in NEC 2023 220.82. Not a permit calculation. 220.82(C) heating/cooling selections can be more involved than “the larger of two numbers,” especially with heat-pump backup strips.
The walk-through lands at about 77.4 A. If 12 months of utility peak demand already approaches 100 A, a 48 A charger may not fit. Use the calculator with measured demand if you can get it.
This is not a permit calculation, a utility approval, or a substitute for a licensed electrician, HVAC contractor, or the authority having jurisdiction. Panel Headroom is an independent educational site. It is not a utility, a certification body, or a contractor. Electrical and generator work that is done incorrectly can cause fire, shock, or carbon monoxide poisoning. Use the adopted electrical code and manufacturer instructions; pull permits where required.