The rule
| Rule | What it covers | Since |
|---|---|---|
| OSHA 29 CFR 1926.404(b)(1) — construction | All 120 V, single-phase, 15 A and 20 A receptacle outlets on construction sites that are not part of the permanent wiring: GFCI protection, or an assured equipment grounding conductor program. NEC 590.6 asks the same of temporary installations and adds the 30 A receptacles. | OSHA 1981; NEC 590.6 (formerly 305-6) 1990s |
29 CFR 1926.404(b)(1)(ii): all 120 V, single-phase, 15 A and 20 A receptacle outlets that are not part of the building's permanent wiring and are in use by employees must have GFCI protection. The alternative, 1926.404(b)(1)(iii), is an assured equipment grounding conductor program — written procedures, a competent person, continuity and grounding tests on every cord set and tool before first use, after repair, after suspected damage, and at least every three months, with colour-coded tape recording each quarter. Most contractors find the GFCI cheaper than the paperwork.
The NEC's version
Article 590.6 asks the same of temporary installations and adds the 30 A receptacles; it also allows listed cord sets and devices with built-in GFCI protection to satisfy the rule for receptacles that lack it. That sentence is why a portable GFCI at the cord counts.
Meeting it in practice
- Spider boxes and temporary panels with GFCI receptacles or GFCI breakers protect what plugs into them — and nothing on a receptacle somewhere else.
- Generators vary: some have GFCI receptacles built in, some have a floating neutral that a plug-in GFCI trips on (generators and inverters).
- A portable GFCI — a plug-head cord, an in-line module, or a rewireable head on the crew's own cord — protects the worker on any source, and travels to the next site. Manual reset, so a tripped saw does not restart on its own (why).
Testing on site
Press TEST before each day's use; a device that fails comes off the job (how often). Keep the devices upstream of the damage: a GFCI at the source end of a 100 ft cord protects the whole cord; one at the tool end protects only the tool.