OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.



February 20, 1987




SUBJECT: Electrical standards for construction, revised Subpart K


In revising its electrical standards for construction, OSHA devised a new format, which divides 29 CFR 1926, Subpart K into four categories. As stated in the preamble to the final rule (51 Federal. Register 25297), OSHA believes that the use of this format can provide for the continued effective coverage of hazards and equipment formerly addressed, with enough flexibility to accommodate other equipment and protective methods in the future. Electrical safety-related work practices, Part II of this new format, carried over work-practice requirements from the former Subpart K. For example, the former 1926.400(g) was moved, without substantive change, and placed in new 1926.417, under Part II of Subpart K.

Questions have arisen regarding the application of newly-revised 29 CFR 1926 Subpart K to the electric utility industry. OSHA has therefore determined to clarify the Subpart with respect to two provisions, 29 CFR 1926.432(a) and 29 CFR 1926.417(b).




  1. 29 CFR 1926.432(a). Section 1926.432(a), requiring that equipment used in certain areas be "identified for use" in those areas by testing laboratories, is not applicable to power generation installations. Section 1926.432 was taken directly from Section 110-11 and 300-6 of the 1981 National Electrical Code. Because installations for the generation, transmission, or distribution of electrical energy are excluded from the scope of the NEC, it was not OSHA's intent that new 1926.432 be applied to such installations.
  2. 29 CFR 1926.417(b). A second concern regarding Subpart K relates to application of 29 CFR 1926.417(b) to electric utilities. That provision, titles "Lockout and tagging of circuits," requires that "equipment or circuits that are deenergized shall be rendered inoperative..." This provision was taken without change from existing Subpart K and no change in required practices is intended. OSHA does not construe this provision to require that all disconnects used for deenergization of equipment or circuits by locked in all instances in the electric utility industry. See 51 Federal Register 25315. Specifically, where there are unique elements of power-generating installations that would make application of locks or other means of rendering equipment inoperable infeasible, the standard should not be read to require locks, provided that an equivalent level of employee safety is achieved by tagging.

    Guidance for implementing this determination may be drawn from pertinent provisions of Subpart V of the Construction Standards, governing construction work performed on power transmission or distribution lines or equipment, including construction in energized substations. Where lines or equipment must be deenergized during construction, 29 CFR 1926.957(b) and 1926.950(d) apply to require appropriate tagging procedures. Thus, to promote uniformity of procedures for deenergizing and tagging of generating installations during all types of work and to maximize the safety to require lockout of installations of electric equipment where lockout is infeasible, as long as the employer is following the procedures for tagging prescribed in 1926.950(d) as specified in 1926.957(b), and is adequately training employees in the use of these procedures.