By EV Charge Cost Editorial Team. Published September 28, 2026, updated October 26, 2026.
Adding an EV charger is usually the biggest new load a home takes on in years. Whether your panel can carry it depends on two different things: the capacity of your electrical service, and physical room in the panel for a new breaker. Neither can be judged from the outside, but you can understand what the electrician is looking at.
What "capacity" means
Your service has an amp rating, usually printed on the main breaker and the panel label. That rating is the total current the house can draw safely at once. It is not the sum of all the breakers; panels routinely hold more breaker ratings than the service could supply simultaneously, because not everything runs at once.
An EV charger breaks that "not everything at once" assumption. It draws full current for hours, often overnight when heating, cooling or a water heater may also run. That is why the code treats it as a continuous load and limits it to 80% of its breaker, and why the electrician counts it at full value.
How big the new load is
At 240 V, the current is the charger power ÷ 240. The table shows the continuous draw at each common size and how long it takes to cover average driving (37 miles a day at 13,500 miles a year) for a 33.5 kWh/100 mi EV.
| Breaker | Continuous draw | Power | Hours for 37 mi/day | Hours for 74 mi/day |
|---|---|---|---|---|
| 20 A | 16 A | 3.84 kW | 3 h 14 min | 6 h 27 min |
| 30 A | 24 A | 5.76 kW | 2 h 9 min | 4 h 18 min |
| 40 A | 32 A | 7.68 kW | 1 h 37 min | 3 h 14 min |
| 50 A | 40 A | 9.60 kW | 1 h 17 min | 2 h 35 min |
| 60 A | 48 A | 11.52 kW | 1 h 5 min | 2 h 9 min |
The pattern matters: a smaller charger draws less current but simply runs longer. If your car is parked ten hours a night, even the 20 A row replaces well over an average day's driving.
What an electrician checks
- A load calculation. Existing major loads (heating, air conditioning, range, dryer, water heater, well pump) are added up using the code method, then the EV circuit is added at full continuous value.
- Service rating and condition. The main breaker, service conductors and panel must be rated for the result, and the panel must be in sound condition.
- Breaker space. A 240 V circuit needs a two-pole breaker slot. A full panel may need rearranging or a subpanel.
- The wire run. Distance from panel to parking spot, wire size for the chosen amperage, and routing.
- Local rules and permits. Most jurisdictions require a permit and inspection for a new 240 V circuit.
If the panel is tight
- Choose a smaller circuit. Most chargers can be set to a lower current. As the table shows, 16–24 A covers typical driving overnight.
- Use load management. Some chargers and add-on energy monitors measure household current and turn the charger down when other loads run, so the total stays under the service rating. Your electrician and local code decide whether that lets the charger count at a reduced value.
- Share one circuit between two chargers instead of adding two. See charging two EVs at home.
- Consider 120 V. A dedicated 120 V circuit adds 1.44 kW, about 4 miles per hour, which is enough for short commutes. See charging on a regular outlet.
- Upgrade the panel or service when the numbers genuinely require it. A service upgrade involves your utility and usually takes longer.
What to gather before the visit
- A clear photo of the panel label, main breaker and breaker directory.
- The list of large appliances, especially electric heating, heat pumps and electric water heaters.
- Your typical and longest daily mileage, and your car's maximum AC charging rate.
- Where you park and where the charger should go.
Do not open the panel yourself. Panel work is for a licensed electrician, under a permit, following the charger manufacturer's installation instructions. For sizing the charger itself, see how many amps you need.