A Level 2 home EV charger generally needs its own dedicated circuit, sized for the charger’s rating and the fact that charging is a continuous load. Level 1 charging uses a standard outlet, but even then, a circuit that is not shared with other heavy loads is a good idea.
The charger’s installation instructions and the electrical code determine the exact circuit requirements.
Why EV Charging Needs Its Own Circuit
EV chargers draw a large amount of current for long periods, often several hours at a time. Under the electrical code, this is treated as a continuous load.
Because of that, the circuit must be sized with extra room above the charger’s rated current. In general, the circuit is sized at 125 percent of the charger’s continuous current. For example, a charger that draws 40 amps would typically need a 50-amp circuit.
Sharing that circuit with other outlets or appliances could overload it, leading to tripped breakers or overheated wiring.
Level 1 vs. Level 2 Circuit Needs
Level 1 charging uses a standard 120-volt outlet. It draws less current, but it still runs for many hours. If the outlet shares a circuit with other devices, such as a freezer or power tools in the garage, the circuit may become overloaded. Using an outlet on a lightly loaded or dedicated circuit helps.
Level 2 charging uses a 240-volt circuit and is almost always installed on its own dedicated circuit. Hardwired chargers connect directly to that circuit, while plug-in chargers use a 240-volt receptacle rated for the load.
Planning the Circuit
Planning a charger circuit starts with the charger’s rating and installation instructions. Many chargers can be set to different current levels, which affects the circuit size.
The panel needs both space for a new breaker and enough capacity for the added load. A load calculation shows whether the home’s service can support the charger. If not, a lower charger setting, a load management device or a panel upgrade may be needed.
The wire size, breaker and receptacle, if used, must all match. Location, wiring distance and GFCI protection requirements also affect the design.
Leave the Installation to a Qualified Electrician
Installing a high-current circuit involves the panel, energized parts and careful sizing. Mistakes can cause overheating, damage to the vehicle or charger and fire risks. A new charger circuit generally requires a permit and inspection in Denver.
Never use an extension cord or adapter as a permanent setup for charging, and never increase a breaker size to stop trips.
If you are planning home charging, our EV charger installation in Denver page explains how charger circuits are planned. For other appliances that need their own circuits, our dedicated circuit installation page may help. Contact us with your charger model.