The device
- UL 943 — Ground-Fault Circuit-Interrupters. Class A 4–6 mA, the trip-time curve, miswire lock-out (2006), self-test (2015). The listing mark on every GFCI we sell.
- UL 943C — Special-purpose GFCIs (Classes C, D, E) for 480 / 600 V industrial circuits.
- UL 1699 — Arc-fault circuit interrupters. UL 1449 — Surge protective devices.
- CSA C22.2 No. 144.1 — the Canadian GFCI standard, harmonized with UL 943; the c(UL)us or cCSAus mark covers both countries.
Where (the National Electrical Code, NFPA 70)
| Rule | What it covers | Since |
|---|---|---|
| NEC 210.8(A) — dwelling units | Receptacles (125 V through 250 V, 50 A or less since 2020) in bathrooms, garages and accessory buildings, outdoors, crawl spaces, unfinished basements, kitchens, sinks (within 6 ft), boathouses, bathtubs and showers (within 6 ft), laundry areas, and indoor damp or wet locations. | Bathrooms 1975; outdoors 1973; kitchens 1987; basements 1990; laundry 2014; 250 V receptacles 2020 |
| NEC 210.8(B) — other than dwelling units | Bathrooms, kitchens and areas with sinks, rooftops, outdoors, indoor damp or wet locations, locker rooms with showers, garages and service bays, crawl spaces, unfinished basements, laundry areas. | Commercial kitchens 2008; broadened 2017 and 2020 |
| NEC 210.8(F) — outdoor outlets, dwellings | Outdoor outlets supplied by single-phase branch circuits 150 V to ground or less, 50 A or less — including hard-wired equipment such as air-conditioner condensers (with a temporary exception for HVAC that most jurisdictions adopted). | 2020 |
| NEC 406.4(D)(2) — replacements where no ground exists | A non-grounding receptacle may be replaced with a GFCI receptacle (or a grounding-type one protected by a GFCI) marked "No Equipment Ground" — the Code's route to protection in two-wire homes. | 1993 (as 210-7(d)) |
| NEC 422.5 — appliances | Certain appliances rated 150 V to ground or less and 60 A or less: automotive vacuums, drinking-water coolers and bottle-fill stations, high-pressure spray washers, tire inflators, vending machines, sump pumps, dishwashers (2020), and others as listed. | Vending machines 2005; dishwashers 2014; broadened 2017 / 2020 |
| NEC Article 680 — pools, spas, hot tubs, fountains | Pump motors (2020: all, cord-connected or hard-wired), underwater luminaires above the low-voltage limit, receptacles within 20 ft of the water, spa and hot-tub equipment. | Pool receptacles 1968 (the first GFCI rule); pump motors broadened 2020 |
- 210.12 — AFCI protection (a different device).
- 406.4(D)(3) — the "GFCI Protected" marking on downstream receptacles; 406.9 and 406.12 — WR and TR devices.
- 590.6 — temporary installations: GFCI on 125 V, 15 / 20 / 30 A receptacles, listed cord sets accepted.
The workplace
| 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 1910.304(b)(3) carries a parallel rule for temporary wiring in general industry; NFPA 70E is the electrical-safety-in-the-workplace standard that references both.
The RCD world
| Rule | What it covers | Since |
|---|---|---|
| IEC 61008 / 61009 / 61540 — RCDs, RCBOs, portable RCDs | Residual-current devices for the 230 V world: 30 mA for additional protection, 10 mA where required, 100–300 mA for fire protection; types AC, A, F and B by the waveform detected. | 1990s; type F 2010s |
- IEC 61008 RCCBs · 61009 RCBOs · 61540 portable RCDs · 62423 Types F and B.
- IEC 60364-4-41 — where 30 mA "additional protection" is required in an installation; BS 7671 (UK wiring regulations, 18th Edition) — the national version.
Editions and adoption
The NEC is revised every three years; a jurisdiction adopts an edition on its own schedule and may amend it. Where this site says "since 2020", it means the 2020 edition of the NEC; whether that binds you depends on what your state or city adopted. UL standards apply to the product at the date of manufacture.