E2 Grounding and Bonding 2

Question 1

What is the minimum size equipment grounding conductor required for a 200-ampere circuit per NEC Table 250.122?

Accepted Answer

4 AWG copper

Answer

NEC Table 250.122 requires a 4 AWG copper equipment grounding conductor for circuits rated up to 200 amperes.

Question 2

Which NEC article specifically addresses grounding and bonding requirements?

Accepted Answer

Article 250

Answer

NEC Article 250 covers all general requirements for grounding and bonding of electrical installations.

Question 3

What is the purpose of bonding jumpers in a commercial electrical system?

Accepted Answer

Ensure electrical continuity and reduce impedance

Answer

Bonding jumpers ensure electrical continuity and create a low-impedance path to facilitate overcurrent device operation during a fault.

Question 4

A separately derived system must have its grounding electrode conductor connected at which point?

Accepted Answer

Source of the separately derived system

Answer

Per NEC 250.30(A), the grounding electrode conductor for a separately derived system must connect at the source (e.g., transformer secondary).

Question 5

What is the maximum resistance allowed between a grounding electrode and the earth per NEC 250.53(A)(2)?

Accepted Answer

25 ohms

Answer

NEC 250.53(A)(2) requires supplemental electrodes when a single rod, pipe, or plate electrode has resistance exceeding 25 ohms.

(E2) E2 Commercial Electrical Inspector Practice Test