Journeyman Electrician Exam (NEC)Wiring Methods and MaterialsMedium
An electrical contractor is installing a series of nonmetallic boxes for a residential lighting circuit. According to NEC 314.17(C), what is the maximum length of conductor that must be left free at each box opening to allow for splices or the connection of luminaires or devices?
- A10 inches
- B6 inches
- C4 inches
- D8 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 6 inches
NEC 314.17(C) mandates that not less than 6 inches of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath, must be left at each outlet, junction, and switch point for splices or the connection of luminaires or devices.
Why the other options are wrong
- A. Incorrect. While more than 6 inches is acceptable, 10 inches is not the minimum specified by the NEC.
- C. Incorrect. 4 inches is too short and does not meet the NEC requirement.
- D. Incorrect. While more than 6 inches is acceptable, 8 inches is not the minimum specified by the NEC.
Free Conductor Length
The NEC requires a minimum length of free conductor at each box opening to facilitate safe and proper termination and splicing of wires.
- NEC 314.17(C) sets the requirement for free conductor length.
- The minimum length is 6 inches.
- Ensures adequate wire length for future maintenance, device replacement, and proper stripping.
Memory trick: Six inches of slack, for a safe wiring track!