Master Electrician Exam (NEC)Services, Feeders, and Branch CircuitsEasy
A commercial kitchen is being renovated, and a new 208Y/120V, 3-phase, 4-wire feeder is being installed from the main service panel to a subpanel in the kitchen. The feeder is protected by a 100A overcurrent device. What is the minimum size copper equipment grounding conductor required for this feeder?
- A4 AWG copper
- B6 AWG copper
- C10 AWG copper
- D8 AWG copper
Show answer & explanationAnswer & explanation
Correct answer: D. 8 AWG copper
According to NEC Table 250.122, for a feeder protected by a 100A overcurrent device, the minimum size for a copper equipment grounding conductor is 8 AWG.
Why the other options are wrong
- A. This size is larger than the minimum required but could be used.
- B. This size is larger than the minimum required but could be used.
- C. This size is too small for a 100A overcurrent device, according to NEC Table 250.122.
Feeder Equipment Grounding Conductor Sizing
The equipment grounding conductor (EGC) for a feeder provides a low-impedance path for ground-fault current from equipment to the service disconnecting means.
- Sized based on the rating of the overcurrent protective device protecting the feeder.
- Refer to NEC Table 250.122.
- Ensures proper operation of overcurrent protective devices during a ground fault.
Memory trick: EGC protects by current, not load.