Charging Plug-In Electric Vehicles at Home
Most drivers of plug-in electric vehicles (PEVs)—which include all-electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs)—charge their vehicles overnight at home using AC Level 1 or AC Level 2 charging equipment. Residential equipment is frequently installed in garages, but outdoor installation and use are also safe, even if the vehicle is being charged in the rain. Outdoor installations require outdoor-rated charging equipment. Charging at a multi-family residential complex requires additional considerations and may be more like public charging than charging at a single-family home.
Installing Charging Equipment in Your Home
Many PEV owners will be able to meet their daily driving range requirements by charging overnight with Level 1 equipment, requiring no additional cost or installation, provided that a power outlet on a dedicated branch circuit is available near their parking location. For drivers with less regular schedules, or longer commutes, Level 2 charging equipment can be installed. State incentives may be available to help offset the cost of charging equipment.
The most basic Level 2 products have standard safety features and status lights. More advanced, "smart" Level 2 products have features such as data collection, user interface systems, enhanced displays, charging timers, communications capabilities, and keypads.
Electricians can inform homeowners whether their home has adequate electrical capacity for vehicle charging. Some homes might have insufficient electric capacity for Level 2 equipment. However, homeowners may have a qualified electrician add circuits to accommodate the capacity needed for Level 2 charging.
The City of San Jose, California, was one of the first to issue requirements for installing vehicle charging systems in single-family homes and duplexes to explain the permitting process and location planning for a home charging unit.
Complying with Regulations
Charging equipment installations must comply with local, state, and national codes and regulations. Appropriate permits may be required from the local building and permitting authorities.
You can learn about related codes and standards on the Codes and Standards Resources page. Electric vehicle charging equipment is considered a continuous load by the National Electrical Code (NEC). Your electrical contractor should understand and use the appropriate NEC for a safe and code-compliant installation. NEC Article 625 contains most of the information applicable to charging equipment. If possible, consult vehicle manufacturer guidance for information about the required charging equipment and learn the specifications before purchasing equipment or electrical services.
In many areas, a site installation plan must be submitted to the permitting authority for approval before installation.
Jurisdictions that have not yet developed a specific permitting process for residential charging equipment installations can refer to the permitting template.
Electricity Costs for Charging
The fuel efficiency of an EV may be measured in kilowatt-hours (kWh) per 100 miles. To calculate the cost per mile of an EV, the cost of electricity (in dollars per kWh) and the efficiency of the vehicle (how much electricity is used to travel 100 miles) must be known. If electricity costs $0.11 per kWh and the vehicle consumes 34 kWh to travel 100 miles, the cost per mile is about $0.04.
If electricity costs $0.11 per kilowatt-hour, charging an EV with a 70-mile range (assuming a fully depleted 24 kWh battery) will cost about $2.64 to reach a full charge. This cost is about the same as operating an average central air conditioner for about 6 hours. To compare the fueling costs of individual models of conventional and plug-in vehicles, see the Vehicle Cost Calculator.
For PEV charging, the stability and planning benefits of household electricity rates offer an attractive alternative compared to traditional types of transportation. Learn more from the report: Comparing Energy Costs per Mile for Electric and Gasoline-Fueled Vehicles.