CEA NEC Wiring and Protection 5 — Questions and Answers
Question 1: What is the minimum size copper conductor permitted for a main bonding jumper in a service panel supplying a 200-ampere service per NEC Table 250.66?
- 6 AWG
- 4 AWG (Correct answer)
- 2 AWG
- 1/0 AWG
Correct answer: 4 AWG
Per NEC Table 250.66, a 200-ampere service with 3/0 AWG or 4/0 AWG service entrance conductors requires a minimum 4 AWG copper bonding jumper.
Question 2: Under NEC 501.15, sealing fittings in Class I, Division 1 conduit systems must be installed within how many inches of an enclosure?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
NEC 501.15(A)(1) requires sealing fittings to be installed within 18 inches of enclosures, switches, circuit breakers, or fuses in Class I, Division 1 locations.
Question 3: Which NEC section requires arc-fault circuit interrupter (AFCI) protection for bedroom circuits in dwelling units?
- NEC 210.8
- NEC 210.12 (Correct answer)
- NEC 215.9
- NEC 240.6
Correct answer: NEC 210.12
NEC 210.12 requires AFCI protection for branch circuits supplying outlets in dwelling unit bedrooms and other specified areas.
Question 4: Per NEC 240.21(C), tap conductors from a feeder that are no longer than 25 feet must have an ampacity of at least what percentage of the feeder ampacity?
- 100%
- 1/3 of the feeder (Correct answer)
- 1/4 of the feeder
- 1/2 of the feeder
Correct answer: 1/3 of the feeder
NEC 240.21(C)(2) allows 25-foot tap conductors if they have an ampacity of at least 1/3 of the rating of the overcurrent device protecting the feeder.
Question 5: What is the required minimum working clearance in front of a 240-volt panelboard installed in a residential dwelling per NEC 110.26(A)(1)?
- 18 inches
- 24 inches
- 30 inches (Correct answer)
- 36 inches
Correct answer: 30 inches
NEC 110.26(A)(1) Condition 1 requires a minimum of 30 inches of working clearance in front of electrical equipment operating at 0–150 volts to ground.
Question 6: Under NEC 352.10, rigid PVC conduit (Type PVC) is NOT permitted to be used in which of the following locations?
- Encased in concrete below grade
- Exposed to sunlight where listed for that use
- Support of luminaires or other equipment (Correct answer)
- Wet locations
Correct answer: Support of luminaires or other equipment
NEC 352.10 lists permitted uses for PVC conduit, and 352.12(E) prohibits its use for the support of luminaires or other equipment not described in the Code.
Question 7: Per NEC 230.23, service entrance conductors installed overhead (service drop conductors) must have a minimum size of:
- 14 AWG copper
- 12 AWG copper
- 8 AWG copper (Correct answer)
- 10 AWG copper
Correct answer: 8 AWG copper
NEC 230.23(B) requires overhead service conductors to be a minimum of 8 AWG copper or 6 AWG aluminum for service drop wiring.
CEA NEC Wiring and Protection 5
What is the minimum size copper conductor permitted for a main bonding jumper in a service panel supplying a 200-ampere service per NEC Table 250.66?