PC Grounding and Bonding 3

Question 1

What is the maximum resistance to ground allowed for a driven ground rod per NEC 250.56 before a second electrode is required?

Accepted Answer

25 ohms

Answer

NEC 250.56 requires a supplemental electrode if a single driven rod has a resistance to ground exceeding 25 ohms.

Question 2

Intersystem bonding terminations (IBTs) are required to be accessible and located within how many feet of the service entrance or the grounding electrode conductor?

Accepted Answer

No distance limit is specified

Answer

NEC 250.94 requires IBTs to be accessible but does not specify a maximum distance from the service; placement is determined by practicality.

Question 3

Which conductor connects the grounded service conductor (neutral) to the grounding electrode system at the service equipment?

Accepted Answer

Main bonding jumper (MBJ)

Answer

The main bonding jumper connects the grounded (neutral) conductor to the equipment grounding conductor at the service equipment per NEC 250.28.

Question 4

When bonding metal water piping in a building, the bonding jumper must be connected to the piping at a point within how many feet of where the water service enters the building?

Accepted Answer

5 feet

Answer

NEC 250.68(C)(1) requires the bonding connection to interior metal water piping within 5 feet of where the pipe enters the building.

Question 5

A grounding electrode conductor for a residential 200A service must be at least what size if using copper?

Accepted Answer

#4 AWG

Answer

NEC Table 250.66 requires a minimum #4 AWG copper GEC for service conductors of 2/0 AWG or smaller copper (typical for 200A residential).

(PC) Professional Electrical Contractor Practice Test

(PC) Professional Electrical Contractor Practice Test

PC Grounding and Bonding 3