Sometimes yes, after a load calculation — 125 amps is more room than 100 amps, not a guarantee. Compare the calculated or measured load plus the charger with 125 amps, not with the size of the cabinet. A 32-amp charger (7.68 kW at 240 V) is a modest add on a lightly loaded 125-amp service; a 48-amp charger, an electric range, or heat-pump backup strips can still use the extra 25 amps.
125-amp services show up on older suburban houses and get asked about less often than 100 or 200, but the method is the same. Educational walk-through: the same 1,800 ft² all-gas example used on the 100-amp page, with a 4,000 VA cooling nameplate entered as an example.
| 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 | 17,580 VA |
| First 10 kVA at 100%, remainder at 40% | 13,032 VA |
| Larger of the heating or cooling values entered, at 100% | 4,000 VA |
| Calculated load | 17,032 VA · 71.0 A at 240 V |
| Compared with this walk-through’s service rating | 71.0 A is under a 125 A rating by 54.0 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.
That walk-through is about 71.0 A, under 125 A by a wider margin than the same house on 100 A. Raise the charger to 48 A and it becomes about 77.4 A, still under in this light example. If 12 months of utility peak demand already sits near 80 A, a 48 A charger may not fit a measured-demand check (peak × 125% plus the new load). Use the panel headroom calculator and a licensed electrician.
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.