Electrician Grounding and Bonding 2

Question 1

For a separately derived system such as a step-down transformer, where must the system bonding jumper be installed per NEC 250.30(A)(1)?

Accepted Answer

At the source of the separately derived system

Answer

At the first overcurrent device downstream of the transformer

Answer

At the transformer primary terminals

Answer

At the remote panelboard served by the transformer

Question 2

Per NEC 250.52(A)(3), a concrete-encased grounding electrode must contain at least how much bare copper conductor or rebar encased in the concrete?

Accepted Answer

20 feet

Answer

10 feet

Answer

15 feet

Answer

25 feet

Question 3

Per NEC 250.56, if a single ground rod electrode has a resistance to earth exceeding what value, a supplemental electrode must be added?

Accepted Answer

25 ohms

Answer

15 ohms

Answer

50 ohms

Answer

100 ohms

Question 4

Which NEC table is used to determine the minimum size of a grounding electrode conductor based on the size of the service entrance conductors?

Accepted Answer

Table 250.66

Answer

Table 250.52

Answer

Table 310.16

Answer

Table 250.122

Question 5

What is the minimum conductor size required for a ground ring grounding electrode per NEC 250.52(A)(4)?

Accepted Answer

2 AWG bare copper

Answer

6 AWG bare copper

Answer

4 AWG bare copper

Answer

1/0 AWG bare copper

Question 6

At what minimum depth below grade must a ground ring electrode be buried per NEC 250.52(A)(4)?

Accepted Answer

30 inches

Answer

18 inches

Answer

24 inches

Answer

36 inches

Question 7

Per NEC 250.53(B), what is the minimum separation required between two ground rod electrodes when more than one is installed?

Accepted Answer

6 feet

Answer

2 feet

Answer

4 feet

Answer

8 feet