Journeyman Electrician Practice Test
Journeyman Electrician Grounding & Bonding Practice Questions
Grounding & Bonding makes up 7 of every 50 questions on a Tigertest Journeyman Electrician practice test. Here are 10 of the 28 questions on it, each with the answer and the reason.
Updated by the Tigertest team. Based on the 2023 National Electrical Code (NFPA 70) and standard electrical theory. Original questions; 50 per test, 70% to pass. State licensing law not included.
1. At the service, the main bonding jumper connects the grounded conductor to:
- A.The utility transformer
- B.The equipment grounding conductor
- C.The grounding electrode alone
- D.The ungrounded conductors
Answer: B. The main bonding jumper connects the grounded service conductor to the equipment grounding conductors and service enclosure, giving fault current a low-impedance path back to the source.
2. In a panelboard fed by a feeder in the same building, the neutral and equipment grounding conductors must be:
- A.Joined by a green bond screw
- B.Connected to a new ground rod
- C.Bonded together at one bar
- D.Kept isolated from each other
Answer: D. Downstream of the service disconnect, the grounded conductor may not be bonded to the equipment grounding conductors or the enclosure. A bond there would put neutral current on grounding paths.
3. A metal underground water pipe qualifies as a grounding electrode when it is in direct contact with earth for at least:
- A.10 ft
- B.20 ft
- C.5 ft
- D.8 ft
Answer: A. A metal underground water pipe in direct contact with the earth for 10 ft or more, electrically continuous to the electrode connection, is a grounding electrode.
4. When a metal underground water pipe is used as a grounding electrode, it must be:
- A.Used as the only electrode
- B.Bonded only to the gas pipe
- C.Supplemented by another electrode
- D.Insulated at the water meter
Answer: C. A metal water pipe electrode must be supplemented by an additional electrode, because the pipe could later be replaced with plastic.
5. A rod or pipe electrode must be in contact with soil for at least:
- A.10 ft
- B.5 ft
- C.8 ft
- D.6 ft
Answer: C. Rod and pipe electrodes must be at least 8 ft long and installed so at least 8 ft is in contact with the soil.
6. Unless listed, a stainless or copper-coated steel ground rod must be at least what diameter?
- A.5/8 in.
- B.3/4 in.
- C.3/8 in.
- D.1/2 in.
Answer: A. Rod electrodes of stainless steel, or copper- or zinc-coated steel, must be at least 5/8 in. in diameter unless listed. Pipe electrodes are at least 3/4 trade size.
7. If rock prevents driving a ground rod vertically or at an angle, it may be buried in a trench at least how deep?
- A.12 in.
- B.18 in.
- C.24 in.
- D.30 in.
Answer: D. Where rock bottom is met, the rod may be driven at an angle up to 45 degrees, and if that fails it may be laid in a trench at least 30 in. deep.
8. A single rod electrode must be supplemented unless its resistance to earth is no more than:
- A.50 ohms
- B.25 ohms
- C.5 ohms
- D.10 ohms
Answer: B. A single rod, pipe or plate electrode must be supplemented by another electrode unless it has a resistance to earth of 25 ohms or less. Most installers simply drive a second rod.
9. What is the minimum copper equipment grounding conductor for a circuit protected at 100 A?
- A.4 AWG
- B.8 AWG
- C.6 AWG
- D.10 AWG
Answer: B. The equipment grounding conductor table gives 8 AWG copper for 100 A. It is sized from the overcurrent device rating, not from the circuit conductors.
10. A concrete-encased electrode made of bare copper must be at least what size?
- A.8 AWG
- B.2 AWG
- C.6 AWG
- D.4 AWG
Answer: D. A concrete-encased electrode is at least 20 ft of bare copper not smaller than 4 AWG, or 20 ft of 1/2 in. or larger reinforcing bar, in concrete in contact with the earth.
Practice all 28 grounding & bonding questions, and the rest of the 200-question bank, in the free Journeyman Electrician training sets. Questions you miss come back until you have mastered them.
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