CME Grounding, Bonding & Overcurrent Protection 2

Question 1

Per NEC 240.4(D), what is the maximum overcurrent protection permitted for a 12 AWG copper branch-circuit conductor?

Accepted Answer

20A

Answer

NEC 240.4(D)(5) limits overcurrent protection for 12 AWG copper conductors to a maximum of 20A.

Question 2

What is the minimum burial depth for a ground ring below the surface of the earth per NEC 250.52(A)(4)?

Accepted Answer

30 inches

Answer

NEC 250.52(A)(4) requires a ground ring to be installed at least 2½ feet (30 inches) below the surface of the earth.

Question 3

When conductors are installed in parallel in multiple raceways, how must equipment grounding conductors be installed per NEC 250.122(F)?

Accepted Answer

In each raceway, each sized per Table 250.122 based on the overcurrent device

Answer

NEC 250.122(F) requires an EGC to be installed in each raceway when parallel conductors are used, with each EGC sized per Table 250.122 for the circuit overcurrent device.

Question 4

A concrete-encased electrode (Ufer ground) must contain at least how many feet of bare copper conductor or steel rebar per NEC 250.52(A)(3)?

Accepted Answer

20 feet

Answer

NEC 250.52(A)(3) requires at least 20 feet of bare copper conductor (4 AWG or larger) or 20 feet of steel rebar (½ inch or larger) encased in concrete for a concrete-encased electrode.

Question 5

What is the primary function of the equipment grounding conductor (EGC) in a branch circuit?

Accepted Answer

To provide a low-impedance fault current path that enables overcurrent device operation

Answer

The EGC provides a low-impedance path for fault current to return to the source, ensuring sufficient current flows to operate the overcurrent protective device and clear the fault.

(CME) Certified Master Electrician Practice Test

(CME) Certified Master Electrician Practice Test

CME Grounding, Bonding & Overcurrent Protection 2