CEA CEA Grounding, Bonding, and Electrical Service Equipment Questions and Answers 1 — Questions and Answers
Question 1: What is the primary purpose of an equipment grounding conductor (EGC)?
- To carry normal load current back to the source
- To provide a low-impedance path for fault current so overcurrent devices operate quickly (Correct answer)
- To reduce voltage drop on branch circuits
- To bond the neutral conductor to the panel
Correct answer: To provide a low-impedance path for fault current so overcurrent devices operate quickly
The EGC provides a low-impedance fault current return path so that a line-to-ground fault causes enough current to trip the overcurrent protective device quickly.
Question 2: What is the difference between grounding and bonding?
- They are the same thing
- Grounding connects the system to earth; bonding connects conductive parts together to equalize potential (Correct answer)
- Bonding connects to earth; grounding connects conductors together
- Grounding is only for high-voltage systems
Correct answer: Grounding connects the system to earth; bonding connects conductive parts together to equalize potential
Grounding establishes a reference connection to earth potential, while bonding electrically connects conductive parts together to eliminate voltage differences between them.
Question 3: According to NEC Article 250, which conductor connects the grounded (neutral) conductor to the equipment grounding conductor at the service?
- Equipment grounding conductor
- Main bonding jumper (Correct answer)
- System bonding jumper
- Grounding electrode conductor
Correct answer: Main bonding jumper
The main bonding jumper (MBJ) connects the grounded conductor to the equipment grounding conductor and the service enclosure at the service equipment.
Question 4: What is a grounding electrode conductor (GEC)?
- The conductor that bonds equipment enclosures together
- The conductor that connects the grounded system conductor or equipment to the grounding electrode (Correct answer)
- The conductor inside flexible metal conduit
- The conductor that returns load current to the transformer
Correct answer: The conductor that connects the grounded system conductor or equipment to the grounding electrode
The GEC connects the grounded service conductor (or equipment) to the grounding electrode system, establishing the earth connection.
Question 5: Which of the following is a listed grounding electrode per NEC 250.52?
- Aluminum water service pipe
- Concrete-encased electrode (Ufer ground) (Correct answer)
- Plastic water pipe with metallic fittings
- PVC conduit buried 30 inches
Correct answer: Concrete-encased electrode (Ufer ground)
A concrete-encased electrode (Ufer ground) — at least 20 feet of #4 AWG or larger bare copper or rebar encased in concrete — is a listed grounding electrode per NEC 250.52(A)(3).
Question 6: When two or more ground rods are used as the grounding electrode system, what is the minimum spacing between them per the NEC?
- 4 feet
- 6 feet
- 8 feet (Correct answer)
- 10 feet
Correct answer: 8 feet
NEC 250.53(B) requires ground rods to be spaced at least 6 feet apart, though greater spacing improves effectiveness.
CEA CEA Grounding, Bonding, and Electrical Service Equipment Questions and Answers 1
What is the primary purpose of an equipment grounding conductor (EGC)?