Journeyman Electrician Exam (NEC)Services, Feeders, and Branch CircuitsEasy
A client requests the installation of a 120-volt, 20-ampere branch circuit for lighting in a dwelling unit. The circuit conductors are run in EMT conduit. What is the minimum size copper equipment grounding conductor (EGC) required for this circuit, according to NEC 250.122?
- ANo. 10 AWG copper
- BNo. 8 AWG copper
- CNo. 12 AWG copper
- DNo. 14 AWG copper
Show answer & explanationAnswer & explanation
Correct answer: C. No. 12 AWG copper
According to NEC Table 250.122, for a circuit with an overcurrent protective device rating of 20 amperes, the minimum size copper equipment grounding conductor required is No. 12 AWG.
Why the other options are wrong
- A. No. 10 AWG copper is required for 60-ampere circuits or larger, not a 20-ampere circuit.
- B. No. 8 AWG copper is required for 100-ampere circuits or larger, not a 20-ampere circuit.
- D. No. 14 AWG copper is the minimum size for a 15-ampere circuit, not a 20-ampere circuit.
EGC Sizing (Branch Circuit)
The minimum size of an equipment grounding conductor (EGC) for a branch circuit is determined by the rating of the overcurrent protective device (OCPD) for that circuit, as specified in NEC Table 250.122.
- Size depends on OCPD rating.
- NEC Table 250.122 is the reference.
- Ensures proper fault current path.
Memory trick: Grounding Wire: OCPD Dictates Diameter.