Journeyman Electrician Exam (NEC)Grounding and BondingEasy
A technician is installing a new 60-ampere, 208-volt, 3-phase circuit for a rooftop HVAC unit. The circuit is protected by a 60-ampere circuit breaker. The circuit conductors are 6 AWG copper. What is the minimum size copper equipment grounding conductor required for this circuit?
- A4 AWG copper
- B10 AWG copper
- C8 AWG copper
- D6 AWG copper
Show answer & explanationAnswer & explanation
Correct answer: B. 10 AWG copper
According to NEC Table 250.122, for a 60-ampere overcurrent protective device, the minimum size copper equipment grounding conductor is 10 AWG.
Why the other options are wrong
- A. This size is significantly larger than required for a 60-ampere circuit.
- C. This size is larger than required for a 60-ampere circuit.
- D. This size is the same as the circuit conductors, but not necessarily the minimum for the EGC.
EGC Sizing (General)
Equipment grounding conductors are sized based on the ampere rating of the overcurrent protective device in the circuit, as found in NEC Table 250.122.
- Based on OCPD rating, not conductor ampacity.
- Provides a low-impedance fault path.
- Ensures OCPD operation during a ground fault.
Memory trick: EGC: OCPD's rating determines its size!