CEA CEA Grounding, Bonding, and Electrical Service Equipment Questions and Answers 2

Question 1

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

Accepted Answer

#2 AWG

Answer

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

Question 2

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

Accepted Answer

8 feet

Answer

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

Question 3

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

Accepted Answer

At the source of the separately derived system

Answer

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.

Question 4

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

Accepted Answer

25 ohms

Answer

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.

Question 5

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

Accepted Answer

Aluminum in direct contact with masonry or earth

Answer

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.

(CEA) Certified Electrical Apprentice Practice Test

(CEA) Certified Electrical Apprentice Practice Test

CEA CEA Grounding, Bonding, and Electrical Service Equipment Questions and Answers 2