CEA Grounding, Bonding, and Electrical Service Equipment Questions and Answers Flashcards

What is the minimum size copper grounding electrode conductor required for a service with a 350 kcmil copper service entrance conductor?

Answer: #2 AWG

Per NEC Table 250.66, a 350 kcmil copper service conductor requires a minimum #2 AWG copper grounding electrode conductor.

What is the minimum burial depth for a ground rod electrode per the NEC?

Answer: 8 feet

NEC 250.53(G) requires ground rods to be driven to a minimum depth of 8 feet into the earth.

In a separately derived system (such as a transformer secondary), where is the system bonding jumper installed?

Answer: At the source of the separately derived system

The system bonding jumper for a separately derived system is installed at the source (the transformer secondary) to bond the grounded conductor to the transformer enclosure and EGC.

What is the maximum resistance permitted for a single ground rod electrode before a supplemental electrode is required per the NEC?

Answer: 25 ohms

Per NEC 250.53(A)(2), if a single ground rod has a resistance to earth exceeding 25 ohms, a supplemental grounding electrode must be added.

Which conductor is NOT permitted to be used as a grounding electrode conductor?

Answer: Aluminum in direct contact with masonry or earth

NEC 250.64(A) prohibits aluminum or copper-clad aluminum grounding electrode conductors where they are in direct contact with masonry or the earth, or subject to corrosive conditions.

What is the purpose of bonding metallic water piping systems in a building?

Answer: To ensure all metallic piping is at the same electrical potential, preventing shock hazards

Bonding the metallic water piping equalizes electrical potential throughout the system, eliminating the risk of shock from voltage differences between piping and other grounded metal.