EV charger wire gauge, also referred to as EV charger diameter or wire size, is 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).
According to the National Electrical Code (NEC), the correct wire gauge for your EV charger installation is determined by the amperage rating of the dedicated EV charger circuit breaker. This specification is crucial, as it directly influences both the efficiency and safety of your EV charging system.
Selecting the correct wire gauge for your EV charger installation is essential for safely handling the continuous load of EV charging. Proper sizing ensures safe current flow, minimizes energy loss, and prevents overheating or fire hazards. It also reduces EV charging voltage drop, which can otherwise lead to reduced charging efficiency, slower charge times, and premature wear on both the charger and vehicle components.
Table of Contents
Key Takeaways
Wire gauge for EV chargers depends on the amperage of your charger and the distance between the charger and the electrical panel.
- Level 1 EV Charger (120V, 12–16A): Use 14 AWG for 12A, 12 AWG for 16A, or long runs.
- Level 2 Plug-in EV Charger (240V, 16–48A):
- 16–24A → 12 AWG
- 32A → 10 or 8 AWG
- 40A → 8 AWG
- 48A → 6 AWG (or 4 AWG for long runs or NM cable)
- High-Amp Hardwired Level 2 EV Charger (48–80A): Use 4 to 2 AWG, possibly #3 or #1 AWG for 80A on long runs.
Wire Sizing Best Practices for EV Charger Circuits
Always increase wire gauge (i.e., use thicker wire) for longer distances or warmer environments to minimize EV charging voltage drop and reduce the risk of overheating. Solid Copper conductors are recommended for EV charging installations due to their superior conductivity, thermal stability, and long-term reliability.
Before installation, verify that your EV charger terminals and any connected EV charging accessories, such as circuit breakers or disconnects, are rated for the wire size you plan to use. Avoid mixing different wire gauges within the same EV charger circuit, as this can lead to uneven current flow, elevated resistance, and localized overheating, particularly under continuous high loads. Thinner segments effectively become a bottleneck, compromising both safety and performance.
To ensure a code-compliant and secure installation, terminate only one wire per terminal, and maintain consistent wire gauge throughout the entire branch circuit unless specifically engineered for transitions.
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’s branch circuit. The table below summarizes the common EV charger wire gauge used in EV charger installations.
| EV Charger Rating (Continuous Loads) | Power Rating of EV Charger (kW) | EV Charger Dedicated Breaker Size (20/80 Rule) | Hot Wire Gauge (AWG) (Copper) | EV Charger Wire Size (mm²) |
|---|---|---|---|---|
| 12 Amp | 2.88 kW | 15 Amp | 14 | 2.08 mm² |
| 16 Amp | 3.84 kW | 20 Amp | 12 | 3.31 mm² |
| 20 Amp | 4.80 kW | 25 Amp | 10 | 5.26 mm² |
| 24 Amp | 5.76 kW | 30 Amp | 10 | 5.26 mm² |
| 28 Amp | 6.72 kW | 35 Amp | 8 | 8.37 mm² |
| 32 Amp | 7.68 kW | 40 Amp | 8 | 8.37 mm² |
| 36 Amp | 8.64 kW | 45 Amp | 6 | 13.3 mm² |
| 40 Amp | 9.60 kW | 50 Amp | 6 | 13.3 mm² |
| 48 Amp | 11.52 kW | 60 Amp | 4 | 21.2 mm² |
| 56 Amp | 13.44 kW | 70 Amp | 4 | 21.2 mm² |
| 64 Amp | 15.36 kW | 80 Amp | 3 | 26.7 mm² |
| 72 Amp | 17.28 kW | 90 Amp | 2 | 33.6 mm² |
| 80 Amp | 19.20 kW | 100 Amp | 2 | 33.6 mm² |
Here are some common usages for the various EV charger wire gauges:
Plug-In EV Charger Wire Sizes
The National Electrical Code (NEC) specifies that the maximum amperage for a plug-in EV charger is 40 amps, requiring a 50-amp circuit breaker. Plug-in chargers are limited by the capacity of NEMA outlets and the safety of removable connections.
Recommended Wire Sizes for Plug-In EV Chargers
| Plug-In EV Charger Rating (Amps) | Power Rating (kW) | Breaker Size (Amps) | Wire Gauge (AWG) | Wire Size (mm²) | EV Charger Outlet |
|---|---|---|---|---|---|
| 12 A | 2.88 kW | 15 A | 14 | 2.08 mm² | NEMA 5-15 (120V) |
| 16 A | 3.84 kW | 20 A | 12 | 3.31 mm² | NEMA 5-20 (120V) |
| 20 A | 4.80 kW | 25 A | 10 | 5.26 mm² | NEMA 6-20 (240V) |
| 24 A | 5.76 kW | 30 A | 10 | 5.26 mm² | NEMA 6-30 (240V) |
| 32 A | 7.68 kW | 40 A | 8 | 8.37 mm² | NEMA 14-50 (240V) |
| 40 A | 9.60 kW | 50 A | 6 | 13.3 mm² | NEMA 14-50 or NEMA 6-50 |
To assist you with the installation process of plug-in EV charger outlets, we recommend checking out our comprehensive guide on installing NEMA outlets for plug-in EV chargers. This guide covers everything you need to know, including how to select the correct outlet for your charger’s amperage, determine the proper dedicated circuit breaker size, choose the right outlet wiring and wire gauge, and provide installation tips.
Hardwired EV Charger Wire Sizes
Hardwired chargers are permanently installed, providing higher power capacity and supporting faster charging rates compared to plug-in chargers. They are ideal for chargers exceeding 40 amps or when a clean, permanent setup is desired.
Recommended Wire Sizes for Hardwired EV Chargers
| Hardwired EV Charger Rating (Continuous Loads) | Power Rating of EV Charger (kW) | EV Charger Dedicated Breaker Size (20/80 Rule) | Hot Wire Gauge (AWG) (Copper) | EV Charger Wire Size (mm²) |
|---|---|---|---|---|
| 12 Amp | 2.88 kW | 15 Amp | 14 | 2.08 mm² |
| 16 Amp | 3.84 kW | 20 Amp | 12 | 3.31 mm² |
| 20 Amp | 4.80 kW | 25 Amp | 10 | 5.26 mm² |
| 24 Amp | 5.76 kW | 30 Amp | 10 | 5.26 mm² |
| 28 Amp | 6.72 kW | 35 Amp | 8 | 8.37 mm² |
| 32 Amp | 7.68 kW | 40 Amp | 8 | 8.37 mm² |
| 36 Amp | 8.64 kW | 45 Amp | 6 | 13.3 mm² |
| 40 Amp | 9.60 kW | 50 Amp | 6 | 13.3 mm² |
| 48 Amp | 11.52 kW | 60 Amp | 4 | 21.2 mm² |
| 56 Amp | 13.44 kW | 70 Amp | 4 | 21.2 mm² |
| 64 Amp | 15.36 kW | 80 Amp | 3 | 26.7 mm² |
| 72 Amp | 17.28 kW | 90 Amp | 2 | 33.6 mm² |
| 80 Amp | 19.20 kW | 100 Amp | 2 | 33.6 mm² |
For those installing a hardwired EV charger, we recommend checking out our comprehensive guide on hardwired EV charger installation. This guide covers essential topics like selecting the correct wire gauge for your charger’s amperage, determining the appropriate dedicated circuit breaker size, and following expert installation practices.
Level 1 EV Charger Wire Size
12-Gauge Wire (12 AWG): Ideal for Level 1 EV chargers operating at 120V.
Level 1 EV chargers are ideal for home use when only a standard 120V outlet is available. They provide slower charging speeds but are convenient for overnight charging of smaller EV batteries or plug-in hybrid vehicles.
With a NEMA 5-15 outlet (12 amps continuous load), it supports up to 1.3 kW. With a NEMA 5-20 outlet (16 amps continuous load), it supports up to 1.7 kW. This setup is perfect for slow, steady Level 1 EV charging.
Level 2 EV Charger Wire Size
Level 2 EV chargers operate at 240V, offering significantly faster charging speeds than Level 1 chargers, making them ideal for daily at-home use. These chargers require higher amperage and thicker wires to accommodate the increased power demand and the continuous load of Level 2 charging.
Wire Size Recommendations for Level 2 EV Chargers
| Level 2 EV Charger Rating (Continuous Loads) | Power Rating of EV Charger (kW) | EV Charger Dedicated Breaker Size (20/80 Rule) | Hot Wire Gauge (AWG) (Copper) | EV Charger Wire Size (mm²) |
|---|---|---|---|---|
| 12 Amp | 2.88 kW | 15 Amp | 14 | 2.08 mm² |
| 16 Amp | 3.84 kW | 20 Amp | 12 | 3.31 mm² |
| 20 Amp | 4.80 kW | 25 Amp | 10 | 5.26 mm² |
| 24 Amp | 5.76 kW | 30 Amp | 10 | 5.26 mm² |
| 28 Amp | 6.72 kW | 35 Amp | 8 | 8.37 mm² |
| 32 Amp | 7.68 kW | 40 Amp | 8 | 8.37 mm² |
| 36 Amp | 8.64 kW | 45 Amp | 6 | 13.3 mm² |
| 40 Amp | 9.60 kW | 50 Amp | 6 | 13.3 mm² |
| 48 Amp | 11.52 kW | 60 Amp | 4 | 21.2 mm² |
| 56 Amp | 13.44 kW | 70 Amp | 4 | 21.2 mm² |
| 64 Amp | 15.36 kW | 80 Amp | 3 | 26.7 mm² |
| 72 Amp | 17.28 kW | 90 Amp | 2 | 33.6 mm² |
| 80 Amp | 19.20 kW | 100 Amp | 2 | 33.6 mm² |
EV Charger Ground Conductor Size
The ground conductor in an EV charger circuit acts as a pathway for excess electrical current to safely flow to ground, preventing electrical shock and damage to equipment. Its size is typically based on the EV charger’s circuit breaker rating, as outlined in NEC Table 250.122.
In my EV charger installations, I always make sure to use the correct gauge ground conductor based on the dedicated EV charger circuit breaker size (not the load or wire size), not only to provide a safe pathway for excess electrical current, but also to ensure it can handle EV charging ground-fault or leakage current without overheating or failure, preserving the integrity and safety of the entire grounding system.
| EV Charger Rating (Continuous Loads) | EV Charger Dedicated Breaker Size (20/80 Rule) | Grounding Conductor (Copper) | Grounding Conductor (Aluminum) |
|---|---|---|---|
| 12 Amp | 15 Amp | 14 AWG | 12 AWG |
| 16 Amp | 20 Amp | 12 AWG | 10 AWG |
| 20 Amp | 25 Amp | 10 AWG | 8 AWG |
| 24 Amp | 30 Amp | 10 AWG | 8 AWG |
| 28 Amp | 35 Amp | 10 AWG | 8 AWG |
| 32 Amp | 40 Amp | 10 AWG | 8 AWG |
| 36 Amp | 45 Amp | 10 AWG | 8 AWG |
| 40 Amp | 50 Amp | 10 AWG | 8 AWG |
| 48 Amp | 60 Amp | 10 AWG | 8 AWG |
| 56 Amp | 70 Amp | 8 AWG | 6 AWG |
| 64 Amp | 80 Amp | 8 AWG | 6 AWG |
| 72 Amp | 90 Amp | 8 AWG | 6 AWG |
| 80 Amp | 100 Amp | 8 AWG | 6 AWG |
For more detailed installation guidelines, refer to our EV Charger Earthing Guide.
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’s 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.
EV Charger Circuit Breaker Size.
The circuit breaker sizing for Electric Vehicle Supply Equipment (EVSE) is governed by the National Electrical Code (NEC), particularly with continuous loads experienced during EV charging.
According to NEC Article 100, a continuous load is defined as one where the maximum current is expected to flow for three hours or more, exactly the case for most EV charging sessions.
To prevent overheating and ensure long-term safety, NEC Section 625.41 requires that the branch circuit and overcurrent protection device be sized to at least 125% of the EV charger’s rated current.
This 125% rule, often referred to as the “80% rule,” ensures the circuit operates at no more than 80% of its rated capacity under continuous load, leaving a built-in safety margin.
For example, a Level 2 EV charger rated at 40 amps would require a 50-amp breaker (40A × 1.25) and properly sized conductors, as confirmed in NEC Article 210.
This principle is essential for preventing thermal overload, maintaining code compliance, and ensuring the long-term safety of your EV charging installation.
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’s 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.
Number of Conductors in EV Charger Branch Circuit
The number of conductors in an EV charger branch circuit depends not only on the type of installation, such as a hardwired EV charger installation or plug-in EV charger installation, but also on the charger’s specifications and whether the system is single-phase or three-phase. Factors like the need for a neutral, support for load sharing, or integrated smart features also influence conductor requirements.
For single-phase EV charger installations, three conductors are common: phase, neutral, and ground, as shown in the single-phase electric vehicle branch circuit below:
For three-phase EV charger installations, four conductors are common: two phase wires, one neutral, and one ground. This is illustrated in the three-phase 240V EV branch circuit example on the subpanel 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 about 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.
James Ndungu is a certified EV charger installer with over five years of experience in EVSE selection, permitting, and installation. He holds advanced credentials, including certification from the Electric Vehicle Infrastructure Training Program (EVITP) and specialized training in EV charging equipment and installation, as well as diplomas in EV Technology and Engineering Fundamentals of EVs. Since 2021, James has tested dozens of EV chargers and accessories, sharing expert insights into the latest EV charging technologies.
