Journeyman Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A temporary construction site requires power for portable tools and lighting. The temporary feeder conductors are run overhead. What is the minimum vertical clearance required for these conductors above areas other than public streets, alleys, roads, or driveways, according to NEC?
- A8 feet (2.44 m)
- B10 feet (3.0 m)
- C12 feet (3.7 m)
- D15 feet (4.6 m)
Show answer & explanationAnswer & explanation
Correct answer: B. 10 feet (3.0 m)
NEC 590.4(J) specifies that temporary overhead feeder conductors and branch circuits must have a minimum vertical clearance of 10 feet (3.0 m) above grade or finished ground, over areas other than public streets, alleys, roads, or driveways. This ensures safety for personnel and equipment below.
Why the other options are wrong
- A. 8 feet is typically for service drops over residential property, not temporary feeders.
- C. 12 feet is required for temporary feeders over residential driveways and commercial areas not subject to truck traffic.
- D. 15 feet is required over commercial areas subject to truck traffic or for voltage exceeding 300V to ground over residential driveways.
Temporary Overhead Feeder Clearance
Temporary overhead feeder and branch circuit conductors must maintain specific vertical clearances above grade, varying by the area beneath them, to ensure safety on construction sites.
- Applies to temporary installations (NEC Article 590).
- Clearance depends on the area (e.g., pedestrian, vehicle traffic).
- Ensures safety from accidental contact.
Memory trick: Temporary wires: Keep a CLEAR path, especially for people and trucks.