Journeyman Electrician Exam (NEC) flashcards

The minimum size of a grounding electrode conductor (GEC) for a metal underground water pipe electrode is determined by the size of the largest service-entrance conductor or equivalent ungrounded conductor, using NEC Table 250.66.

• NEC Table 250.66 is the primary reference for GEC sizing.
• The GEC size is based on the service-entrance conductor size, not the service OCPD, when conductors are larger.
• Metal underground water pipe is a common and preferred grounding electrode.

Memory trick: Service conductor size dictates the ground wire's might.