The purpose of ground-fault protection on temporary wiring installations during construction, remodeling, maintenance, repair or demolition of buildings, structures or equipment is to ensure personnel protection. Section 590.6 re-quires ground-fault circuit interrupter (GFCI) protection for any temporary power source supplying electrical equipment on the job site. However, questions have been raised within the past few National Electrical Code (NEC) cycles whether GFCI protection was required for all sources of power on a job site or only utility-supplied power. Do generators used on job sites also require GFCI protection for circuits used by personnel, or are generators exempt from the requirement?

GFCI protection of 15- and 20-ampere, 120-volt receptacles, not part of the permanent wiring of a building, was inserted into Section 210-8(b) of the 1975 NEC. An exception exempted two-wire 5-kilowatt (kW) and smaller generators from this requirement. In the 1984 NEC, GFCI-protection requirements for construction sites were moved to Article 305 covering temporary wiring. In the 1999 NEC, GFCI protection for 30-ampere, 120-volt receptacles was added.

In the 1999 NEC, Section 305.6, Exception No. 1 read: “Receptacles on a 2-wire, single phase portable or vehicle-mounted generator rated not more than 5 kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, shall be permitted without ground-fault protection for personnel.” This was deleted in the 2002 NEC to ensure that all 15-, 20- and 30-ampere, 120-volt receptacles on any size generator must be GFCI-protected. Questions remained about whether to apply GFCI protection on generator receptacles.

A sentence was added to 590.6 in the 2008 NEC that GFCI protection for temporary power receptacles were required for power de-rived from an electric utility company or from on-site generated power sources. There still were questions.

For the 2011 NEC, Proposal 3-140 was accepted in principle by Code-Making Panel 3, which should finally answer all questions on this issue as follows: “590.6 Ground-Fault Protection for Personnel. Ground-fault protection for personnel for all temporary wiring instal-lations shall be provided to comply with 590.6(A) and (B). This section shall apply only to temporary wiring installations used to sup-ply temporary power to equipment used by personnel during construction, remodeling, maintenance, repair, or demolition of build-ings, structures, equipment, or similar activities. This section shall apply to power derived from an electric utility company or from an on-site-generated power source.

“A. Receptacle Outlets. Temporary receptacle installations used to supply temporary power to equipment used by personnel during con-struction, remodeling, maintenance, repair, or demolition of buildings, structures, equipment, or similar activities shall comply with the requirements in 590.6(A)(1) through 590.6(A)(3), as applicable.”

“Exception: In industrial establishments only, where conditions of maintenance and supervision ensure that only qualified personnel are involved, an assured equipment-grounding conductor program as specified in 590.6(B)(2) shall be permitted for only those receptacle outlets used to supply equipment that would create a greater hazard if power were interrupted or having a design that is not compatible with GFCI protection.

“1. Receptacle Outlets Not Part of Permanent Wiring. All 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets that are not a part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel.”

“2. Receptacle Outlets Existing or Installed as Permanent Wiring. Ground-fault circuit-interrupter protection for personnel shall be pro-vided for all 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets If a receptacle(s) is installed or existing as part of the permanent wiring of the building or structure and is used for temporary electric power. Listed cord sets or devices incorporating listed ground-fault circuit-interrupter protection for personnel identified for portable use shall be permitted.”

“3. Receptacles on 15 kW or less Portable Generators. All 125-volt and 125/250-volt, single-phase, 15-, 20-, and 30-ampere receptacle out-lets that are a part of a 15 kW or smaller portable generator shall have listed ground-fault circuit-interrupter protection for personnel. Listed cord sets or devices incorporating listed ground-fault circuit-interrupter protection for personnel identified for portable use shall be permitted for use with 15 kW or less portable generators manufactured or remanufactured prior to January 1, 2011.”

The text added to (3) for the 2011 NEC process clarifies that the all 125-volt and 125/250-volt, single-phase, 15-, 20- and 30-ampere re-ceptacle outlets that are a part of a 15-kW or smaller portable generator must have GFCI protection. Any 15-kW or smaller portable gen-erators manufactured or remanufactured prior to Jan. 1, 2011, can use listed cord sets or devices incorporating listed ground-fault circuit interrupter protection for personnel for portable use. Any new generators must incorporate GFCI protection.

ODE is a staff engineering associate at Underwriters Laboratories Inc., in Research Triangle Park, N.C. He can be reached at 919.549.1726 and [email protected].