Key takeaways
- Size the breaker at 125 percent of the charger's draw.
- Choose plug-in or hardwired based on how the charger will be used and how much current it needs.
- Place the charger where the cable reaches the vehicle's port without strain, and where it stays dry.
- A load calculation shows whether your panel can take the new circuit.
- Installation is permitted work, and an inspection follows.
Plug-in or hardwired
There are two ways to connect a Level 2 charger. A plug-in unit goes into a 240-volt receptacle, most often a 14-50 type, similar to what many ranges and RVs use. A hardwired unit connects straight to the circuit conductors with no plug.
Plug-in is convenient and lets you take the charger with you if you move. The weak point is the receptacle. Repeated plugging, heat from a long charge and a loose connection can wear it out, so it needs to be a good-quality receptacle installed correctly. Hardwiring removes that weak point and generally allows a higher charging current. Many chargers let you set the current lower than their maximum, which helps if your panel capacity is limited.
A charger that is mounted outdoors, or in a garage that gets damp, should be rated for that environment. Check the enclosure rating on the label and follow the installation instructions.
Circuit requirements
Charging is a continuous load, so the breaker is rated at 125 percent of the charger's current. A charger set to 32 amps takes a 40-amp breaker. One set to 40 amps takes a 50-amp breaker. The circuit has its own breaker, and it is not shared with anything else.
The wire size depends on the breaker rating, the type of cable or conductor, and the length of the run. A long run from the panel to a far corner of the garage may need heavier wire than a short one to limit voltage drop. The wire has to be protected, either in conduit or in an approved cable, and the connections have to be tight and rated for the conductors used.
Ground-fault protection is also part of the picture. Depending on the charger and the code edition your jurisdiction follows, it may be built into the charger or provided by the breaker. Your electrician will know which applies. This is not something to improvise with parts from a hardware store.
Choosing the location
Start with the vehicle. Charge ports sit in different places, and the cable needs to reach without being stretched, kinked or lying where someone will drive over it. If two vehicles share the garage, or you may change vehicles, place the charger so it can serve either parking position.
Then look at the route from the panel. In an attached garage with the panel on the other side of the wall, the run is short. If the panel is in a basement, the cable runs through joists and may need to cross finished ceilings. A detached garage needs an underground feeder in conduit, and in Southwest Ohio that means trenching through clay soil that stays wet in spring and freezes in winter. The conduit has to be buried to the depth the code requires and use fittings rated for wet locations.
Indoors, the charger is mounted at a height the code sets, off the floor and away from where it can be hit. Keep it clear of water sources and away from places where stored items could pile up against it.
The load calculation
Before a new circuit goes in, the electrician checks that the service can handle it. That is the load calculation. It adds up the demand from the house: general lighting and outlets, the kitchen range, dryer, water heater, heating and cooling, and anything else that is large and fixed, then adds the charger.
The code allows several methods. One works from the size of the house and the ratings on major appliances. Another uses the house's actual measured demand over a period. The result is compared with the rating of the service and the panel.
If the total fits, the circuit goes in as planned. If it does not, the options are a charger set to a lower current, a load management device that shares capacity with a big appliance, or a panel upgrade. Older homes with 100-amp service or full panels are where this comes up most often, so it is worth finding out before you buy a charger. For the full picture on equipment, see EV charger installation.
Permits and inspection
A new 240-volt circuit is permitted work. In Ohio, permits and inspections run through your local building department, and the process differs by city and county. The electrician typically files the permit, installs the circuit, and schedules the inspection.
The inspector looks at the breaker, the wire, the grounding, the connections and the mounting. If anything is wrong, it gets corrected and rechecked. Keep the permit record with your home papers. It helps when you sell the house or talk to your insurer.
Some electric utilities offer information on EV charging and may have their own rate options. Ask yours before you finish the install. If you are ready to get a charger circuit looked at, you can contact us about your home.
Frequently asked questions
Can I install a Level 2 charger myself?
The charger circuit involves 240-volt wiring, work inside the panel, and a permit. It should be done by a licensed electrician. Mistakes here lead to overheated connections, which can start a fire during a long charge.
Does the charger have to be in the garage?
No. It can be outside on an exterior wall or a post if the charger is rated for outdoor use and the circuit is installed for wet locations. A garage is simpler because the run is usually shorter and the unit is out of the weather.
What if my panel is full?
There are options short of a new panel. A lower-current charger, a load management device, or rearranging the panel with tandem breakers where permitted can sometimes work. An electrician can tell you which are allowed for your panel.
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