Journeyman Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsHard
A temporary power installation is set up for a construction site. The temporary feeders and branch circuits are run as open conductors. According to NEC Article 590, what is the minimum clearance required for these open conductors above areas accessible to pedestrians only?
- A3.0 m (10 ft)
- B2.4 m (8 ft)
- C3.7 m (12 ft)
- D4.6 m (15 ft)
Show answer & explanationAnswer & explanation
Correct answer: A. 3.0 m (10 ft)
NEC Section 590.4(J) refers to the clearances in 225.18. For open conductors, 225.18(1) specifies a minimum clearance of 3.0 m (10 ft) above areas accessible to pedestrians only. This ensures adequate safety overhead clearance for foot traffic.
Why the other options are wrong
- B. This clearance is insufficient for open conductors above pedestrian areas.
- C. This clearance is required for areas accessible to vehicles, not just pedestrians.
- D. This clearance is for areas accessible to trucks or where the voltage exceeds 750V, not solely pedestrians.
Temporary Open Conductor Clearance
The minimum vertical distance required by the NEC for open conductors of temporary installations above areas accessible only to pedestrians.
- Applies to temporary installations (NEC 590).
- Specific to open conductors over pedestrian areas.
- Minimum 3.0 m (10 ft) clearance.
Memory trick: Ten feet high, for walkers passing by, temporary wires in the sky.