Perhaps the greatest advancement in worker safety over the past 30 years has been the development and implementation of ground-fault circuit-interrupter (GFCI) protection. Both the National Electrical Code (NEC) and the Occupational Safety and Health Administration (OSHA) have initiated requirements designed to afford a superior level of protection for both employees and the general public who may be exposed to the hazards of electricity. The purpose of this article will be to explore this development as it relates to GFCI protection for temporary wiring as required by Article 305 of the NEC and OSHA’s 1926, Subpart K, Electrical Standards.
Photo 1. Typical "Spider box" supplies GFCI protected receptacles for use on construction sites.
Both the NEC and OSHA recognize that workers performing construction, demolition and maintenance activities are especially vulnerable to the hazards of electricity. Frequently, workers have environmental and physical conditions which directly impact their ability to work safely around the hazards associated with the use of electrical tools and equipment. Essentially, the NEC developed and OSHA adopted a two-prong approach to affording protection to workers. Until recently, (1996 NEC) Article 305 and OSHA 1926.404(b) have both permitted either the use of the Assured Equipment Grounding Conductor Program (AEGCP) or the use of GFCI protection for all 125-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites. The concept of the AEGCP is that frequent and regular inspection and testing of all equipment grounding conductors, receptacles and attachment plugs, will "assure” that the continuity of the EGC is maintained and that a low-impedance grounding path will protect workers sufficiently against the hazards of electrical shock by facilitating the operation of the overcurrent device. GFCI devices, on the other hand, sense an unbalance or leakage current in the area of 4-6 mA and open the circuit in a 1/40 of a second to provide protection against electrocution.
Diagram 1. GFCI protection required for 15, 20, and 30 ampere, 125-volt receptacles on construction sites.
The 1996 NEC
Two significant changes occurred in Section 305-6, Ground-Fault Protection for Personnel, in the 1996 NEC. First, the scope of the GFCI requirements was greatly expanded by removing the limitation to construction sites only. Prior to the 1996 NEC, the GFCI requirements for 15- and 20- ampere, 125-volt receptacle outlets, only applied to personnel on construction sites. The 1996 NEC removed this limitation and expanded the scope of the provision to include all "temporary wiring installations utilized to supply temporary power to equipment used by personnel during construction, remolding, maintenance, repair, or demolition of buildings, structures, equipment or similar activities.” This was a dramatic expansion of the scope and resulted in a significant advancement for worker safety.
Diagram 2. Principles of operation of GFCI protective devices
The second significant change was the restrictions placed on the use of the AEGCP. Prior to the 1996 NEC, either the GFCI or the AEGCP could be utilized to meet the requirements of this section. In the 1996 NEC, the use of the AEGCP was strictly limited to "other receptacles not covered in (a).” This meant that, for other than industrial establishments (see exception) all 15- and 20-ampere, 125-volt, single-phase receptacle outlets had to be provided with GFCI protection.
Interestingly, CMP-3 also clarified that when providing GFCI protection, cord sets incorporating listed GFCI protection for personnel are permissible.
Diagram 3. Typical protective GFCI devices
The changes in the 1996 NEC were a great step, a leap, towards enhancing worker safety. Subsequent revisions have continued to expand the scope of the protection to include 30-ampere, 125-volt, single-phase receptacle outlets and to clarify that where GFCI protection is required, such protection is required, regardless if the receptacle exists or is considered to be part of the permanent wiring of the building. In other words, if personnel are performing any of the covered activities, (construction, demolition, maintenance, etc.), they must be provided some form of GFCI protection, regardless if the outlet exists or is part of the permanent wiring of the building.
Often this is accomplished by the use of listed cord sets which incorporate the GFCI protection into the cord set. Notice that the wording of Section 305-6(a) currently permits "cord sets or devices incorporating listed ground-fault circuit interrupter protection for personnel identified for portable use.” Two points relevant to this provision. First, note that the cord set must utilize listed GFCI protection, not that the cord set must be listed. This sentence structure is intentionally different from other NEC sections mandating similar requirements. That is because OSHA does permit employers to construct their own extension cord sets. There are several conditions that must be met but the practice is acceptable. Requiring the cord sets to be listed would severely limit this provision. Secondly, the cord sets must utilize GFCI protection which is identified for portable use. Such protection includes "open neutral” protection which enhances personnel safety where such devices are subject to the possibility of losing a neutral connection. For this reason, it is not permissible to utilize standard GFCI receptacles, intended for permanent installation only, as part of a "shop-made” cord set.
Diagram 4. GFCI tripping curves showing time and milliampere values
OSHA Construction Standards
Since the early 1970’s, OSHA Construction Electrical Standards have been driven by the NEC. Current requirements parallel the 1984 edition of the NEC. In fact, Section 1926. 404(a) Note, states, "If the electrical installation is made in accordance with the National Electrical Code ANSI/NFPA 70-1984, exclusive of Formal Interpretations and Tentative Interim Amendments, it will be deemed to be in compliance with 1926.403 through 1926.408, except for 1926.404(b)(1) and 1926.405(a)(2)(ii)(E), (F), (G), and (J).” Unfortunately, as we have just discussed, significant changes in the NEC have occurred which are not currently enforceable by OSHA. The restriction on the AEGCP for example, does not exist within the OSHA regulations. The addition of the 30-ampere, 125-volt receptacle outlet is not included as well. The scope of application for GFCI requirements for OSHA is still limited to construction sites only.
Needless to say, there exists great differences between the NEC requirements and the OSHA regulations. From an enforcement point of view and from a safety point of view this is troublesome. Section 6(b) of the OSHA Act mandates steps that must be taken before OSHA can promulgate a new rule. Logistically, OSHA is simply not capable of keeping up with the latest developments in the NEC.
This fact, however, ought not change employer strategies for protecting personnel from electrical shock. The use of GFCI protection provides a level of safety superior to that of the AEGCP and it can be implemented in an easier and more cost-efficient manner for the employer. OSHA regulations are a minimum safety standard for protecting workers. Particularly when it comes to GFCI requirements, employers should follow the provisions of Article 305 and strive to enhance personnel protection by adhering to the stronger of the two standards.
Read more by Michael Callanan