United States
Hong KongGFCI and temporary power
Ground fault circuit interrupter protection, or an assured equipment grounding conductor program, is required for temporary power on construction sites under 29 CFR 1926.404(b)(1).
A short rule with an alternative in it, and the alternative is what makes it a good question.
The two options
GFCI protection on all 125-volt, single-phase, 15, 20 and 30 ampere receptacle outlets not part of the permanent wiring.
Or an assured equipment grounding conductor program, which is a written program of inspection and testing of cords and equipment.
A question asking what is required and offering the assured grounding program as an option is testing whether you know both exist. GFCI is far more common in practice, which is why the alternative gets forgotten.
What a GFCI does
Compares current going out against current coming back. A difference means current is going somewhere else, which on a construction site usually means through a person. Two ways to comply. Breakers protect wiring.
It trips fast and at a low current, well below what a circuit breaker responds to. A breaker protects the wiring; a GFCI protects the person.
The assured grounding program
Written, with a designated competent person, covering inspection of cords before each use and periodic testing of continuity and terminal connections.
Tested equipment is marked to show it has been. That marking is what an inspector looks for.
Other temporary power points
- Extension cords are of the three-wire type and rated for hard or extra-hard usage
- Cords are not run through doorways or windows where they can be damaged
- Damaged cords are removed from service
- Temporary lighting is guarded where it could be contacted
Common questions
What is required for temporary power on site?
GFCI protection, or an assured equipment grounding conductor program, under 29 CFR 1926.404(b)(1).
What is an assured equipment grounding program?
A written program of inspection and testing of cords and equipment, with a competent person and marking of tested items.
What does a GFCI do?
Compares outgoing and returning current and trips when they differ, which means current is flowing somewhere else.
Is a circuit breaker enough?
No. A breaker protects the wiring; a GFCI protects the person.
What type of extension cords are required?
Three-wire type rated for hard or extra-hard usage, not run where they can be damaged.