CEI Electrical Code & Standards 3 — Questions and Answers
Question 1: According to the NEC, what is the minimum burial depth for a rigid metal conduit (RMC) installed under a residential driveway?
- 6 inches
- 12 inches (Correct answer)
- 18 inches
- 24 inches
Correct answer: 12 inches
NEC Table 300.5 requires RMC to be buried at least 6 inches under a residential driveway, but under a street or road 24 inches is required; under driveways for dwellings 12 inches applies.
Question 2: Under the NEC, what minimum headroom is required in electrical equipment rooms containing service equipment rated 1200 amperes or more?
- 6 feet (Correct answer)
- 6 feet 3 inches
- 6 feet 6 inches
- 7 feet
Correct answer: 6 feet
NEC 110.26(E)(1)(a) requires a minimum headroom of 6 feet 3 inches for service equipment rooms, but 6 feet applies in specific lower-rated scenarios.
Question 3: What is the maximum number of overcurrent devices (excluding the main breaker) permitted in a lighting and appliance branch circuit panelboard?
- 24
- 36
- 42 (Correct answer)
- No limit
Correct answer: 42
NEC 408.15 limits lighting and appliance branch circuit panelboards to a maximum of 42 overcurrent devices.
Question 4: Which NEC section requires arc-fault circuit interrupter (AFCI) protection for dwelling unit bedroom circuits?
- 210.8
- 210.12 (Correct answer)
- 210.20
- 210.52
Correct answer: 210.12
NEC 210.12 requires AFCI protection for branch circuits supplying outlets in dwelling unit bedrooms and many other areas.
Question 5: Under the NEC, luminaires installed in clothes closets must maintain a minimum clearance of how many inches from storage space when they are surface-mounted fluorescent types?
- 6 inches (Correct answer)
- 12 inches
- 6 inches — not permitted at all
- No clearance required
Correct answer: 6 inches
NEC 410.16(C)(3) permits surface-mounted fluorescent luminaires in clothes closets with a minimum 6-inch clearance from the storage area.
Question 6: According to NFPA 70E, what is the primary purpose of an Energized Electrical Work Permit?
- To authorize overtime pay for electricians
- To document justification and safety procedures for working on energized equipment (Correct answer)
- To certify that equipment meets UL listing requirements
- To record the nameplate data of electrical equipment
Correct answer: To document justification and safety procedures for working on energized equipment
NFPA 70E requires an Energized Electrical Work Permit to document why energized work is necessary and the safety procedures to be followed.
Question 7: Under NEC 250.122, if the overcurrent device protecting a circuit is 400 amperes, what is the minimum size equipment grounding conductor required using copper conductors?
- 3 AWG (Correct answer)
- 2 AWG
- 1 AWG
- 1/0 AWG
Correct answer: 3 AWG
NEC Table 250.122 specifies a minimum 3 AWG copper equipment grounding conductor for circuits protected by 400-ampere overcurrent devices.
CEI Electrical Code & Standards 3
According to the NEC, what is the minimum burial depth for a rigid metal conduit (RMC) installed under a residential driveway?