Breaker sizing and wire gauge specifications for hardwiring a 48-amp Level 2 EV charging station
Short answer
Hardwiring a 48-amp Level 2 EV charger requires a dedicated 60-amp, 240-volt two-pole circuit breaker and 6 AWG copper THHN wire in conduit or 4 AWG copper NM-B cable. Electrical code mandates sizing the breaker to 125 percent of the continuous 48-amp load to prevent overheating. The station must be directly hardwired, as standard plug receptacles cannot safely support 48-amp continuous charging.
Hardwiring a 48-amp Level 2 electric vehicle charger requires a dedicated 60-amp, 240-volt two-pole circuit breaker paired with 6 AWG copper THHN conductors in conduit or 4 AWG copper NM-B Romex.
Electric vehicle supply equipment draws maximum electrical current for hours at a time, classifying it as a continuous load under National Electrical Code (NEC) Article 625. Residential 48-amp charging delivers 11.5 kilowatts of power, demanding precise branch circuit conductor sizing and thermal protection to prevent overheating.
If you only do one thing: Size the dedicated circuit breaker to exactly 125% of the continuous 48-amp draw—a 60-amp breaker—and install 6 AWG THHN copper wire inside conduit to ensure code-compliant thermal capacity.
- Overcurrent protection sizing: NEC Section 625.41 classifies EV charging as a continuous load, requiring overcurrent protection sized at 125% of the 48A continuous rating, which specifies a 60A, 240V two-pole breaker.
- Conduit wire gauge: Specify 6 AWG (American Wire Gauge) copper conductors rated for 75°C or 90°C (such as THHN/THWN) inside conduit, which provides an allowable ampacity of 65 amps under NEC Table 310.16.
- Non-metallic sheathed cable limit: When installing Type NM-B (Romex) cable, specify 4 AWG copper because NEC Section 334.80 restricts NM-B to the 60°C column, where 6 AWG is limited to 55 amps and cannot support a 60A breaker.
- Equipment ground sizing: Install a minimum 10 AWG copper equipment grounding conductor to satisfy NEC Table 250.122 for a 60-amp branch circuit overcurrent device.
- Termination torque ratings: Fasten all breaker lugs and charger terminal blocks using a calibrated torque tool to manufacturer specifications (typically 20 to 50 inch-pounds) to prevent high-resistance thermal failures.
- Direct hardwire requirement: Terminate conductors directly into the charging station lugs, as plug-and-receptacle setups like NEMA 14-50 are limited by code to a 50-amp breaker and a 40-amp continuous charging rate.
- Watch out for: Using 6 AWG NM-B Romex on a 60A breaker, which violates NEC ampacity rules (rated for only 55A at 60°C) and creates severe fire hazards under multi-hour 48A thermal loads.
- Watch out for: Voltage drop exceeding 3% on runs beyond 80 feet, which requires upsizing the conductor from 6 AWG to 4 AWG copper to prevent slow charging speeds and excessive conductor heat.
- Watch out for: Main electrical panel overloading; verify that the existing service panel has sufficient capacity under an NEC Article 220 load calculation before adding a continuous 60A load.
Calculate your electrical panel's existing load margin under NEC Article 220, and if 60 amps of continuous capacity is available, run 6 AWG THHN copper through conduit to the charger location. For complex load calculations or professional electrical installations, schedule a consultation with ARS/Rescue Rooter at 866-399-2885.