Yes, if you have qualifying maximum-demand data, typically 12 months of utility peaks. The usual check is: take that peak, multiply by 125%, add the new EV load, and compare the total with the ampacity of the feeder or the rating of the service. Public permit materials, including the City of Orlando EV charging checklist, paraphrase those conditions. It is still your electrician and the AHJ who decide whether the data and the arithmetic qualify.
This is often the fairest picture of an existing house, because it uses what the house actually drew rather than a stack of nameplates. A simple educational example, not a permit form:
| Step | Example A | Example B |
|---|---|---|
| 12-month peak | 9.7 kW (40.4 A) | 18 kW (75.0 A) |
| Peak × 125% | 50.5 A | 93.8 A |
| New 32 A charger at nameplate | 32 A | 32 A |
| Total vs a 100 A service | 82.5 A, under | 125.8 A, over |
| Same total vs a 200 A service | under | 125.8 A, under |
The 30-day recording exception, used when a full year of data is missing, has extra limits. Trade commentary notes that the exception is not available where the service has a renewable energy system or peak-load shaving. Fifteen-minute interval data is the natural match; hourly averages can hide short peaks.
The panel calculator’s measured-demand mode runs this arithmetic, and can optionally show a more conservative total that also takes the new EV load at 125%. Commentaries disagree on that last point.
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.