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Toolbox talk · 10 min · Electrical

GFCI and Temporary Power

Hazards: Electric shock and electrocution from a ground fault in a cord-and-plug tool · Damaged extension cord or missing ground prong · Wet ground, rain or standing water around temporary receptacles · Fire and insulation damage from an undetected fault

Why it matters

Exposure to electricity killed 62 construction workers in 2022 — 5.7% of all construction deaths that year — according to BLS Census of Fatal Occupational Injuries data in CPWR's July 2024 Data Bulletin. OSHA's own construction eTool lists lack of ground-fault protection as one of the five most frequent causes of electrical incidents, right alongside improper use of extension and flexible cords.

Key points

  • GFCIs or a written program — pick one. 1926.404(b)(1)(i): either GFCIs under (b)(1)(ii), or an assured equipment grounding conductor program under (b)(1)(iii) with a competent person, quarterly tests and records.
  • Every temporary 15- and 20-amp outlet. (b)(1)(ii) covers all 120-volt single-phase 15- and 20-ampere receptacles that are not part of the building's permanent wiring and are in use by employees.
  • 5 milliamps, 1/40 of a second. The GFCI compares current out against current back and cuts power when they differ by about 5 mA — long before the current through you becomes lethal.
  • It will not save you from line contact. OSHA states it directly: a GFCI does not protect against holding two energized conductors, or against contacting an overhead power line.
  • Look at the cord before each day's use. Deformed or missing pins, cut jacket, taped splice, cracked housing — (b)(1)(iii)(C) puts damaged equipment out of service until it is repaired.
  • A trip is information, not a nuisance. Find the fault. Moving the tool to an unprotected outlet removes the only thing standing between the fault and the next person to pick it up.

Do / Don't

Do

  • Push the test button on the GFCI when you plug in for the day.
  • Keep cords out of drive lanes, doorways and standing water.
  • Route cord overhead or along a wall, on hooks, never on staples or nails.
  • Tag and remove any tool with a cracked case or a missing ground prong.

Don't

  • Cut off a ground prong or force a three-prong plug into two slots.
  • Reset a GFCI a second time without finding out why it tripped.
  • Run flexible cord through a wall or doorway as permanent wiring.
  • Assume a double-insulated tool means you can skip ground-fault protection.

Quick site check

  • Test every temporary GFCI on this floor right now, and write down the ones that fail.
  • Pull the cords out of the gang box and lay them out: any missing prongs, taped splices or cut jackets?
  • Find the temporary lighting: are the lamps guarded against breakage, as 1926.405(a)(2)(ii) requires?
Discussion — ask the crew
  1. Walk to the nearest temporary receptacle on this site: is there a GFCI on it, and when was it last tested?
  2. Who here has had a GFCI trip this week — and what did you do next, reset it or find out why?
  3. Pick up the cord nearest you and look at the plug: all three prongs there, no cracked jacket, no tape over a splice?
  4. If a GFCI keeps tripping on a saw, whose call is it to take that saw out of service, and how do we tag it?
  5. Where on this site are we running cord through standing water, a doorway or a drive lane today?
Refs: 29 CFR 1926.404(b)(1)(i)-(iii) — Ground-fault protection: GFCIs or an assured equipment grounding conductor program, the 120-volt 15- and 20-ampere receptacle rule, daily visual inspection, the 3-month test interval and the test record · OSHA Construction eTool — Ground-Fault Circuit Interrupters (GFCI): how a GFCI works, the 5-milliampere trip level, and what it does not protect against · OSHA Construction eTool — Electrical Incidents: the five most frequent causes of electrical incidents on construction sites · 29 CFR 1926.405(a)(2)(ii) and (g)(2) — Temporary wiring: grounding-type receptacles, guarded lamps; flexible cords, splices and strain relief · 29 CFR 1926.416(a)(1) and (e)(1)-(e)(2) — Working near energized circuits; worn or frayed cords shall not be used; cords not fastened with staples or nails · CPWR Data Bulletin, July 2024 — Fatal Injury Trends in the Construction Industry (BLS Census of Fatal Occupational Injuries 2022, chart 8)Sign-in sheet included in the printed version

Frequently asked questions

It requires one of two things. Under 29 CFR 1926.404(b)(1)(i) the employer shall use either ground-fault circuit interrupters as specified in (b)(1)(ii) or an assured equipment grounding conductor program as specified in (b)(1)(iii). Most contractors choose GFCIs, because the alternative is a written program with a competent person, quarterly testing and records.

1926.404(b)(1)(ii): all 120-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites which are not part of the permanent wiring of the building or structure and which are in use by employees. Receptacles on a two-wire, single-phase portable or vehicle-mounted generator rated not more than 5 kW are excepted when the generator's circuit conductors are insulated from the frame and all other grounded surfaces.

OSHA's construction eTool describes it this way: the GFCI compares the amount of current going to and returning from equipment along the circuit conductors, and when the amount going differs from the amount returning by approximately 5 milliamperes, the GFCI interrupts the current. It is designed to shut off power within as little as 1/40 of a second.

No, and OSHA says so plainly: the GFCI will not protect you from line contact hazards — a person holding two hot wires, a hot and a neutral wire in each hand, or contacting an overhead power line. It protects against the most common form of shock, the ground fault, and it also protects against fires, overheating and destruction of wire insulation.

If you run the assured equipment grounding conductor program, 1926.404(b)(1)(iii)(C) requires a visual inspection before each day's use for external defects such as deformed or missing pins or insulation damage. The continuity and terminal tests of (b)(1)(iii)(D) are required before first use, after repairs, after any incident that could have caused damage — a cord run over, for example — and at intervals not to exceed 3 months.

No. 1926.416(e)(2) prohibits fastening extension cords with staples, hanging them from nails or suspending them by wire. 1926.405(g)(2) also rules out using flexible cord as a substitute for permanent wiring or running it through walls, floors or doorways.

No. A GFCI that trips repeatedly is reporting a fault in the tool or the cord, and 1926.404(b)(1)(iii)(C) says equipment found damaged or defective shall not be used until repaired. Tag it, take it out of service and get it fixed.

Sources & references

Content checked against these sources — last reviewed August 28, 2026.

Results are estimates for planning purposes and do not replace a competent person's evaluation or an engineer's design. Follow the OSHA standards that apply to your work and your employer's written program.

By — Editorial team of SteelToeTools.com (published by LSEA SAS) Updated