What size copper Equipment Grounding Conductor (EGC) is required for two Level II EVSE circuits on 40-ampere circuits?

In the context of grounding for electric vehicle supply equipment (EVSE), an Equipment Grounding Conductor (EGC) is essential for safety. The NEC (National Electrical Code) provides guidelines for determining the size of the EGC based on the overcurrent protection device and the rating of the circuits.

For circuits rated at 40 amperes, the NEC specifies that the minimum size for the copper EGC should be based on the size of the circuit's overcurrent protection. In this case, with the circuit rated at 40 amperes, the corresponding EGC size is typically 10 AWG copper. This size provides adequate grounding capabilities to ensure protection against electrical faults.

In addition to safety considerations, using the correct gauge also helps to maintain system integrity and reduce the risk of damage during fault conditions. Ensuring compliance with these standards helps to safeguard against potential hazards and ensures that the charging equipment operates safely.

Larger conductors, such as 8 AWG, may be used in specific applications that require increased capacity but exceed what is necessary for 40 amperes. Smaller sizes, like 12 AWG or 14 AWG, would not meet the minimum requirements for grounding under the NEC for this application, thus posing potential safety risks.