NEC 590 mandates electrical safety for temporary power installations, like construction sites. Find the new location of its GFCI requirements in the NEC.

NEC Article 590, as well as its subsets, handle the electrical safety of “Temporary Installations”. In the Code book, Temporary Installations include: temporary electrical power & lighting installations. These are typically seen in construction sites (temporary lighting for theaters & movie sets are addressed in NEC 520 and NEC 540, respectively). Subset 590.7 (which is a new location, previously NEC 590.6) defines the required GFCI protection for all temporary powered set-ups, whether they are supplied by existing wiring, temporary wiring, or portable generators. But what does 590.7 say it covers?

National Electrical Code 590.7 clarifies the Ground Fault protection guidelines for temporary power used for equipment in construction, remodeling, maintenance, repair, and demolition. It has two lettered parts; 590.7(A) gives requirements for GFCI protection from power supplied by receptacles, and 590.7(B), which is temporary power derived from something outside the scope stated in 590.7(A).

Part A of NEC 590.7 gives the requirements for receptacle outlets, to be more specific, 3 different kinds; Outlets not a part of the permanent wiring, outlets that are a part of the existing (or just installed) wiring, & receptacles from portable generators. Their standards are numbered and as follows:

1.) Part 1 is for receptacle outlets not a part of any permanent wiring installation. These temporary systems, when 125V to ground, single phase, 15-30 amps, require Class A (5mA +/-1) GFCI protection.

2.) Part 2 is for receptacle outlets that were either part of an existing, or newly installed permanent wiring installation. These permanent systems when 125V to ground, single phase, 15-30 amps, require Class A (5mA +/-1) GFCI protection.

Also note, these two numbered sections have an exception, stating that if a GFCI device is listed for portable use in either of the named temporary power-up environments, it will be permissible in lieu of a GFCI protected outlet.

3.) Part 3 is for receptacles from portable generators that have a capacity up to 15-kW. It has 2 lettered parts, a & b which are:

590.7(A)(3)(a): All 125V & 125/250V to ground, single phase, 15-30 amps outlets (individually on a generator, not the generator as a whole), require Class A (5mA +/-1) GFCI protection.

590.7(A)(3)(b): mentions that if the generator is being used in “Damp or Wet Locations”, the receptacles on the generator need to comply with NEC 406.9(A) & (B). That NEC section dictates weather resistance in enclosures (x. IP ratings, hoods, covers, etc.).

The portable generators have a similar exception as the previous 2 parts, where listed for portable use GFCI equipment is allowed to meet the standard, except only for generators manufactured (or remanufactured) before January 1st of 2015. Generators made after those dates need listed GFCI receptacles integrated in their systems.

Part B of NEC 590.7 states to follow the same standards outlined from the previous section, which again means all 125V & 125/250V to ground, single phase, 15-30 amps outlets require Class A (5mA +/-1) GFCI protection. There is an exception for equipment not conducive to GFCI protection, and it needs to be manually tested, tracked, & reported to Authorities Having Jurisdiction (AHJs) to ensure optimal personnel safety, as dangerous electrical leakage can be involved during operation in temporarily powered environments.

The 2026 version of NEC 590 kept things fairly similar to the previous iterations regarding temporary power and Ground fault protection. It still requires Class A Ground Fault protection for 15-30 Amp receptacles in most temporarily powered jobs. They did rearrange where information showed up in the Code, such as the GFCI protection section for temporary power in the 2026 NEC being 590.7, while the 2023 version of the NEC is 590.6. They also rearranged some of the structure, like portable use GFCIs being an Exception for certain systems, originally it was written individually in each numbered subsection of the Code.