Do you need a panel upgrade for an EV charger?

The first question on every charger call in Lockport is not which charger. It is whether the panel can take it. On the 1960s ranches on 100 amps the answer is often no. On the 1990s two-stories east of the canal, with 150 or 200 amps on paper, the answer is “probably, once we do the math.” Here is the math.

How much does a Level 2 charger draw?

A Level 2 charger runs on a 240-volt circuit and draws 32, 40 or 48 amps depending on the unit and how it is set. The circuit is sized 25 percent above that, so a 40-amp charger needs a 50-amp breaker and a 48-amp charger needs a 60. It is a continuous load: the car charges for six or eight hours, not for the ninety seconds a microwave runs. That is why it gets its own circuit and why the panel has to have the capacity, not merely the slot.

What the electrician calculates

The code load calculation for a house adds up the square footage at a set number of watts per foot, the kitchen and laundry circuits, and every fixed appliance: the range, the dryer, the water heater if it is electric, the air conditioner, the furnace blower, the well pump on the Homer Glen side. Then it applies demand factors, because not everything runs at once, and adds the charger at its full continuous rating. The result is compared to the service size.

A 200-amp service on a two-story with a gas range, gas dryer and one air conditioner usually has 60 or 70 amps of headroom. A charger fits. A 100-amp service on a ranch with an electric range, an electric dryer, a window unit in every bedroom and a hot tub does not, no matter how many slots the panel has open.

Most of the inputs are readable without a visit. The year the house went up, the brand and amperage stamped on the panel door, whether the range and dryer run on gas or electricity, and how far the panel sits from the garage are usually enough to run the numbers and have the estimate land on the first try.

The three outcomes when the panel is full

1. A charger with load management. Several chargers can share a circuit with the dryer or throttle themselves when the house is drawing hard. It is the cheapest fix on a house that is close to the line, and a real answer, not a workaround.
2. A subpanel. When the service has capacity but the panel has no slots, a subpanel gives the charger and the next few circuits somewhere to land, for a fraction of a service change.
3. A service upgrade. When the house is on 100 amps and adding a car, the panel is the right call, and the charger goes in the same day. It is also the moment to plan for the heat pump or the second car.

The circuit itself, the conduit run and what the charger install costs are on the EV charger page. The panel work, when that is the answer, is on the panel upgrades page.