Licensed Electrical Contractor Electrical Contractor Electrical Codes & Standards 1 — Questions and Answers
Question 1: Per NEC 230.71(A), what is the maximum number of service disconnecting means permitted for a single service?
- 3 disconnects
- 6 disconnects (Correct answer)
- 8 disconnects
- 12 disconnects
Correct answer: 6 disconnects
NEC 230.71(A) limits the number of service disconnects to six switches or circuit breakers for any single service. This rule ensures a reasonable number of operations are needed to de-energize a service while still allowing flexibility in panel design.
Question 2: According to NEC Chapter 9, Table 1, what is the maximum allowable conduit fill percentage when more than two conductors are installed in a raceway?
- 31%
- 40% (Correct answer)
- 53%
- 60%
Correct answer: 40%
NEC Chapter 9, Table 1 limits conduit fill to 40% of the cross-sectional area when more than two conductors are installed. This prevents excessive heat buildup and makes conductor pulling practical. One conductor allows 53% fill, and two conductors allow 31%.
Question 3: Per NEC 230.24(B), what is the minimum clearance required for service drop conductors passing over a residential driveway?
- 10 feet
- 12 feet (Correct answer)
- 15 feet
- 18 feet
Correct answer: 12 feet
NEC 230.24(B) requires service drop conductors to maintain a minimum clearance of 12 feet above residential driveways. The 10-foot clearance applies only to pedestrian-accessible areas, while 18 feet is required over public streets subject to truck traffic.
Question 4: Per NEC Table 310.15(B)(3)(a), what ampacity adjustment factor applies when 4 to 6 current-carrying conductors are installed together in the same raceway or cable?
- 0.50
- 0.70
- 0.80 (Correct answer)
- 0.90
Correct answer: 0.80
NEC Table 310.15(B)(3)(a) requires an 80% (0.80) adjustment factor when 4 to 6 current-carrying conductors share a raceway or cable, because bundled conductors trap heat and reduce each conductor's ability to dissipate it. Higher quantities of conductors require progressively lower adjustment factors.
Question 5: According to NEC Table 250.122, what is the minimum size copper equipment grounding conductor required for a circuit protected by a 60-ampere overcurrent device?
- 12 AWG
- 10 AWG (Correct answer)
- 8 AWG
- 6 AWG
Correct answer: 10 AWG
NEC Table 250.122 requires a minimum 10 AWG copper equipment grounding conductor for circuits protected by overcurrent devices up to 60 amperes. The EGC size is based on the rating of the overcurrent protective device, not the load current.
Question 6: Per NEC 240.4(D), what is the maximum overcurrent protection permitted for a 14 AWG copper conductor used in a branch circuit?
- 10 amperes
- 15 amperes (Correct answer)
- 20 amperes
- 25 amperes
Correct answer: 15 amperes
NEC 240.4(D) sets a hard limit of 15 amperes for overcurrent protection of 14 AWG copper conductors, regardless of the conductor's calculated ampacity under derating conditions. This is one of the small-conductor exceptions that override the standard ampacity table values.
Licensed Electrical Contractor Electrical Contractor Electrical Codes & Standards 1
Per NEC 230.71(A), what is the maximum number of service disconnecting means permitted for a single service?