What size equipment grounding conductor is required for a 70-amp circuit?

What size equipment grounding conductor is required for a 70-amp circuit?

• A. 6 AWG
• B. 4 AWG
• C. 8 AWG
• D. 10 AWG

Answer: (C)

The size of the equipment grounding conductor is determined by the overcurrent device protecting the circuit, using NEC Table 250.122. Its purpose is to provide a low-impedance path for fault current so the protective device can trip. For a circuit protected at 70 amperes, the minimum copper EGC size required is 8 AWG. So 8 AWG copper satisfies the requirement; using a larger size (like 6 or 4 AWG) is allowed but not necessary, while a smaller size (like 10 AWG) would not meet code. If aluminum is used, the required size would be different and larger according to the table.

The size of the equipment grounding conductor is determined by the overcurrent device protecting the circuit, using NEC Table 250.122. Its purpose is to provide a low-impedance path for fault current so the protective device can trip. For a circuit protected at 70 amperes, the minimum copper EGC size required is 8 AWG. So 8 AWG copper satisfies the requirement; using a larger size (like 6 or 4 AWG) is allowed but not necessary, while a smaller size (like 10 AWG) would not meet code. If aluminum is used, the required size would be different and larger according to the table.