EV charger wire gauge, also referred to as EV charger diameter, or wire size is the the thickness of wires used in an electrical vehicle branch circuit. EV charger wire size is measured in American Wire Gauge or sometimes in millimeters squared (mm²).
EV charger wire gause is determined by the electrical vehicle branch circuit breaker, and directly impacts the electric vehicle branch circuit performance and safety of your EV charger installation.
Table of Contents
EV Charger Wire Gauge Chart
The EV Charger Wire Gauge Chart below lists common electrical vehicle branch circuit wire sizes for Level 1 and Level 2 EV chargers. It shows the wire image and specifies the appropriate wire gauges (AWG) for different power levels and current draws.
Common EV Charger Wire Gauge
EV charger wire gauge is determined by the amperage of the circuit breaker in an electric vehicle branch circuit, the table below summarizes common EV charger wire gauge used in EV charger installations.
| EV Charger Wire Gauge ( American Wire Gauge) | EV Charger Wire Size (mm²) | Electric Vehicle Branch Circuit | Power Rating of EV Charger (kW) |
|---|---|---|---|
| 14 AWG | 2.08 mm² | 15 Amp Circuit | 2.8 kW |
| 12 AWG | 3.31 mm² | 20 Amp Circuit | 3.8 kW |
| 10 AWG | 5.26 mm² | 30 Amp Circuit | 5.7 kW |
| 8 AWG | 8.36 mm² | 40 Amp Circuit | 7.6 kW |
| 6 AWG | 13.30 mm² | 50 Amp Circuit | 9.6 kW |
| 4 AWG | 21.15 mm² | 60 Amp Circuit | 11.5 kW |
Here are some common usages for the various EV charger wire gauges:
Level 1 EV Charger Wire Size
- 12-Gauge Wire (12 AWG): Suitable for a Level 1 EV charger operating at 120V with a maximum power of 3.8 kW and a current draw of up to 20 amps.
Level 2 EV Charger Wire Size
- 10-Gauge Wire (10 AWG): Suitable for Level 2 EV charger operating at 240V with a maximum power of 5.7 kW and a current draw of up to 30 amps.
- 8-Gauge Wire (8 AWG): Suitable for Level 2 EV charger operating at 240V with a maximum power of 7.6 kW and a current draw of up to 40 amps.
- 6-Gauge Wire (6 AWG): Suitable for Level 2 EV charger operating at 240V with a maximum power of 9.6 kW and a current draw of up to 50 amps.
- 4-Gauge Wire (4 AWG): Suitable for Level 2 EV charger operating at 240V with a maximum power of 11.5 kW and a current draw of up to 60 amps.
Factors to Consider When Choosing EV Charger Wire Gauge
Electric Vehicle Branch Circuit Load (Charging Station Power)
The primary factor influencing your choice of EV charger wire gauge is the electrical load of your EV branch circuit. To determine the appropriate wire gauge, you must first understand the total electrical load of your EV charger. According to the National Electrical Code (NEC), the total current draw must be less than 80% of the circuit breaker’s rated limit due to derating requirements for continuous loads.
The higher the electric vehicle branch circuit load (charging station power), the larger the cable size should be to support the electrical current flowing to the charger. for example, Level 1 uses 14 AWG (2.08 mm²) for 120V, 2.8 kW up to 15 amps, and 12 AWG (3.31 mm²) for 120V, 3.8 kW up to 20 amps. Level 2 uses 10 AWG (5.26 mm²) for 240V, 5.7 kW up to 30 amps, 8 AWG (8.37 mm²) for 240V, 7.6 kW up to 40 amps, 6 AWG (13.3 mm²) for 240V, 9.6 kW up to 50 amps, and 4 AWG (21.2 mm²) for 240V, 11.5 kW up to 60 amps.
EV Charger Circuit Breaker Size.
The breaker size for EV charger installation is determined by the wiring configuration and the desired charge rate of the EV charger. Here are the key considerations:
Breaker Sizing and Wire Sizes:
- For Level 1 EV charging (typically 120V), breakers are usually rated between 15A to 20A, with corresponding wire sizes typically ranging from 14 AWG (for 15A) to 12 AWG (for 20A).
- For Level 2 EV charger installations (240V), breakers typically range from 30A to 60A. The wire sizes can range from 10 AWG (for 30A) up to 6 AWG (for 60A), depending on the specific installation requirements.
- According to the National Electrical Code (NEC), the breaker should have a 20% margin above the expected load to ensure safe operation.
Distance from Electrical Panel
The distance between the EV charger’s electrical panel and the EV charger itself influences the choice of cable used in EV charger installations. The greater the distance, the larger the cable size needed to compensate for voltage drops (a voltage drop of no more than 3% is generally recommended).
EV charging voltage drops occur when the electric vehicle branch circuit current travels through a long cable. Using an inadequate cable size can result in inefficient and potentially hazardous EV charging. To mitigate voltage drops, we recommend using an EV charging subpanel.
Future Electric Vehicle Branch Circuit Expansion
If you plan to expand your electrical vehicle branch circuit, it’s wise to install a wire gauge that accommodates future growth, for example when installing a Level 1 EV charger, but in the future, you plan to install a Level 2 EV charger it wise to use Level 2 EV charger wire size to save you from costly upgrades down the road.
EV Charging Cable Number of Conductors
The number of conductors in an EV charger cable depends on the type of EV charger installation.
For single-phase EV charger installations, three conductors are necessary: phase, neutral, and ground as shown in the single-phase electric vehicle branch circuit below:
For three-phase EV charger installations, four conductors are required: two phases, neutral, and ground as shown in the three-phase electric vehicle branch circuit below:
These conductors are bundled within a single cable and are typically composed of multiple metal strands to ensure flexibility and durability. The choice between single-phase and three-phase installations depends on your EV charger branch circuit and the specifications of the charging station.
Learn more on wiring an electric vehicle branch circuit:
Copper vs. Aluminum EV Charger Wiring
When considering EV charger installations, copper wiring surpasses aluminum due to its superior thermal properties, which significantly impact performance and safety.
Here’s why we recommend copper wire for EV charger installation:
- Superior Conductivity: Copper offers significantly better conductivity than aluminum. This translates to lower resistive losses, minimizing heat generation within the cable. This is crucial for EV chargers that deliver high currents for extended periods.
- Enhanced Safety: Lower heat generation with copper reduces the risk of overheating and potential fire hazards, especially during longer EV charging sessions.
- Reliable Connections: Copper’s superior malleability allows for tighter and more reliable connections at the charger terminals, further enhancing safety and preventing power loss.
Conclusions
In conclusion, selecting the appropriate EV charger wire gauge is crucial for ensuring the efficient and safe operation of your electric vehicle charging station. Consider factors such as the charging station power requirements, distance from the electrical panel, potential future expansions, and the choice between copper and aluminum wiring. By carefully evaluating these considerations, you can make an informed decision that optimizes performance while maintaining safety standards for your EV charger installation.
About the Author: James Ndungu
James Ndungu, founder and editor-in-chief of Electric Vehicle Geek, brings over five years of hands-on experience in Electric Vehicle Supply Equipment (EVSE) selection, permitting, and installation. He specializes in assisting businesses and homeowners in the United States with a seamless transition to electric vehicles.
As a certified EV charger installer and holder of advanced certifications, including the EVITP (Electric Vehicle Infrastructure Training Program), Diploma in Electric Vehicle Technology, and Diploma in Engineering Fundamentals of Electric Vehicles, I provide expert guidance and in-depth reviews on the latest EV charging equipment.
