Master Electrician Exam (NEC)Services, Feeders, and Branch CircuitsEasy
A master electrician is installing a new 20A, 120V branch circuit for a bathroom receptacle in a dwelling unit. The circuit will serve only this receptacle. What is the minimum size copper equipment grounding conductor (EGC) required for this circuit?
- A14 AWG
- B8 AWG
- C10 AWG
- D12 AWG
Show answer & explanationAnswer & explanation
Correct answer: D. 12 AWG
According to NEC Table 250.122, for a branch circuit protected by a 20A overcurrent device, the minimum size copper equipment grounding conductor is 12 AWG.
Why the other options are wrong
- A. 14 AWG copper is for 15A circuits, not 20A circuits.
- B. 8 AWG copper is significantly larger than required for a 20A circuit.
- C. 10 AWG copper is larger than required for a 20A circuit.
Equipment Grounding Conductor Sizing (NEC 250.122)
The equipment grounding conductor (EGC) provides a low-impedance path for ground-fault current from equipment and enclosures to the service disconnecting means, ensuring overcurrent devices operate properly.
- Sized based on the rating of the overcurrent protective device in the circuit.
- Referenced in NEC Table 250.122.
- Must be copper, aluminum, or copper-clad aluminum.
Memory trick: EGC: Grounding conductor, sized by the breaker's bite.