CEI Branch Circuit & Feeder Inspection 2 — Questions and Answers
Question 1: Which NEC article governs the installation requirements for feeders, including their overcurrent protection and conductor sizing?
- Article 210
- Article 215 (Correct answer)
- Article 220
- Article 225
Correct answer: Article 215
NEC Article 215 covers feeders — the conductors and equipment between the service equipment and the final branch circuit overcurrent devices.
Question 2: Per NEC 215.2(A)(1), feeder conductor ampacity must be not less than which of the following?
- 80% of the total calculated load
- 100% of non-continuous load plus 125% of continuous load (Correct answer)
- 125% of the total calculated load
- 100% of the total calculated load
Correct answer: 100% of non-continuous load plus 125% of continuous load
NEC 215.2(A)(1) requires feeder ampacity to equal 100% of non-continuous loads plus 125% of continuous loads to account for heat buildup during sustained operation.
Question 3: Under the 10-foot feeder tap rule per NEC 240.21(B)(1), which condition must be met for a tap conductor to be installed without overcurrent protection at the tap point?
- The tap conductor must be in a raceway
- The tap conductor ampacity must not be less than the feeder OCPD rating
- The tap must not exceed 10 feet and have an ampacity of at least 1/10 the feeder OCPD rating
- The tap conductor must not exceed 10 feet and terminate in a single OCPD (Correct answer)
Correct answer: The tap conductor must not exceed 10 feet and terminate in a single OCPD
Per NEC 240.21(B)(1), tap conductors not over 10 feet must be enclosed, not over 10 feet long, and terminate in a single circuit breaker or set of fuses that limit the load to the tap conductor's ampacity.
Question 4: Which conductor in a feeder must be identified by white or gray insulation, or three continuous white stripes for sizes 6 AWG and smaller per NEC 200.6?
- Ungrounded (hot) conductor
- Grounded (neutral) conductor (Correct answer)
- Equipment grounding conductor
- High-leg conductor
Correct answer: Grounded (neutral) conductor
NEC 200.6 requires grounded conductors (neutral) 6 AWG and smaller to be identified by continuous white or gray insulation, or three continuous white stripes.
Question 5: Per NEC 230.79(C), what is the minimum rating for the service disconnect for a single-family dwelling unit?
- 60 amperes, 2-wire
- 100 amperes, 3-wire (Correct answer)
- 150 amperes, 3-wire
- 200 amperes, 3-wire
Correct answer: 100 amperes, 3-wire
NEC 230.79(C) mandates a minimum 100-ampere, 3-wire service disconnect for single-family dwellings to accommodate modern electrical loads.
Question 6: When a feeder is tapped under the 25-foot tap rule (NEC 240.21(B)(2)), what is the minimum ampacity required for the tap conductor?
- Not less than 1/3 the ampere rating of the feeder OCPD (Correct answer)
- Not less than 1/2 the ampere rating of the feeder OCPD
- Equal to the feeder OCPD ampere rating
- Not less than 1/10 the ampere rating of the feeder OCPD
Correct answer: Not less than 1/3 the ampere rating of the feeder OCPD
Per NEC 240.21(B)(2), the 25-foot tap rule requires the tap conductor ampacity to be not less than 1/3 the rating of the feeder overcurrent device.
Question 7: An inspector finds that feeder conductors supplying a panelboard are routed through a wall without any protection. The feeder is not in conduit and passes within 1.25 inches of the edge of a wood stud. What violation exists?
- No violation; feeders do not require protection
- The conductors require nail plates per NEC 300.4(A)(1) (Correct answer)
- The feeder must be installed in conduit per NEC 215.6
- The conductors must be increased one wire gauge
Correct answer: The conductors require nail plates per NEC 300.4(A)(1)
NEC 300.4(A)(1) requires steel nail plates at least 1/16 inch thick when cables or conductors pass through bored holes within 1.25 inches of the edge of a framing member.
CEI Branch Circuit & Feeder Inspection 2
Which NEC article governs the installation requirements for feeders, including their overcurrent protection and conductor sizing?