Journeyman Electrician’s Exam Journeyman Electrician's Grounding and Bonding 4 — Questions and Answers
Question 1: When two ground rods are used as a supplemental electrode system, what is the minimum spacing between them per NEC 250.53(B)?
- 3 feet
- 4 feet
- 6 feet (Correct answer)
- 8 feet
Correct answer: 6 feet
Per NEC 250.53(B), rod and pipe electrodes must be spaced at least 6 feet apart to avoid overlapping effective ground areas.
Question 2: A concrete-encased grounding electrode (Ufer ground) must have at least how many feet of bare or zinc-coated steel reinforcing bars?
- 10 feet
- 15 feet
- 20 feet (Correct answer)
- 25 feet
Correct answer: 20 feet
Per NEC 250.52(A)(3), the concrete-encased electrode requires at least 20 feet of one or more bare steel reinforcing bars in direct contact with earth.
Question 3: Which of the following is the correct term for the low-impedance path intended to carry fault current back to the source?
- Grounding electrode system
- Effective ground-fault current path (Correct answer)
- Equipment bonding jumper
- Neutral conductor route
Correct answer: Effective ground-fault current path
The effective ground-fault current path is the intentional, low-impedance path that carries fault current from the fault point back to the electrical supply source.
Question 4: At a subpanel in a detached garage fed by a feeder from the house, which conductors must be run to the subpanel?
- Hot, neutral only — bond neutral to ground at the subpanel
- Hot, neutral, and a separate equipment grounding conductor (Correct answer)
- Hot and equipment grounding conductor only
- Hot only — ground locally with a new electrode
Correct answer: Hot, neutral, and a separate equipment grounding conductor
A feeder to a separate structure must include a separate equipment grounding conductor; the neutral and ground must not be bonded at the subpanel.
Question 5: What is the minimum size conductor required for a ground ring surrounding a building per NEC 250.52(A)(4)?
- 4 AWG bare copper
- 2 AWG bare copper (Correct answer)
- 1/0 AWG bare copper
- 6 AWG bare copper
Correct answer: 2 AWG bare copper
Per NEC 250.52(A)(4), a ground ring must consist of at least 2 AWG bare copper conductor encircling the building.
Question 6: When using aluminum as a grounding electrode conductor, what special installation precaution must be taken near the ground or in contact with masonry?
- It must be covered with insulating tape
- It cannot be used within 18 inches of the earth or in contact with masonry (Correct answer)
- It must be installed in PVC conduit only
- It must be coated with anti-oxidant compound
Correct answer: It cannot be used within 18 inches of the earth or in contact with masonry
Per NEC 250.64(A), aluminum or copper-clad aluminum GECs cannot be used within 18 inches of the earth or in contact with masonry.
Question 7: The supply-side bonding jumper in a separately derived system serves the same function as which component at the service entrance?
- Grounding electrode conductor
- Main bonding jumper (Correct answer)
- Equipment grounding conductor
- Neutral conductor
Correct answer: Main bonding jumper
The supply-side bonding jumper at a separately derived system performs the same bonding function as the main bonding jumper does at the service entrance.
Journeyman Electrician’s Exam Journeyman Electrician's Grounding and Bonding 4
When two ground rods are used as a supplemental electrode system, what is the minimum spacing between them per NEC 250.53(B)?