Letters of Interpretation

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. Each 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.

These letters of interpretation and the standards they address may not apply to OSHA State Plans. State Plans are required to have standards and enforcement programs that are at least as effective as OSHA's and may have different or additional requirements. Please see OSHA-approved State Plans for more information.

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Date Title Standard Number
Recognition of ANSI/ASSE Z244.1 "Control of Hazardous Energy - Lockout/Tagout and Alternative Methods" consensus standard 1910.6, 1910.147, 1910.147(c)(4)(ii)
LOTO: minor servicing exemption and the use of a lockable on/off switch as an alternate measure to provide effective protection. 1910.147, 1910.147(a)(2)(ii)
Printing Industry: Lock Out/Tag Out and the essential elements of the inch-safe-service technique 1910.147, 1910.147(f)(1), 1910.147(a)(2)(ii), 1910.147(a)(3)(ii)
Lock out/Tag out periodic inspection requirements. 1910.147, 1910.147(c)(6), 1910.147(c)(6)(i), 1910.147(c)(6)(i)(B), 1910.147(c)(6)(i)(C), 1910.147(c)(6)(i)(D), 1910.147(c)(7)(iii), 1910.147(c)(7)(iv)
Clarification of "authorized" and "affected" employees and proper energy control procedures. 1910.147(b), 1910.147(c)(4), 1910.147(c)(7)(i), 1910.147(d), 1910.147(d)(4)(i), 1910.147(f)(3)(ii), 1910.147(f)(3)
Motor-control-circuit switches and relays are prohibited from being used as energy isolating devices. 1910.147, 1910.147(c)(1), 1910.147(a)(2)(ii)
Response to Edison Electric Institute's concerns regarding draft Instruction CPL 2-1.18A, "Enforcement of the Electric Power Generation, Transmission and Distribution Standard." 1910.269, 1910.269(d), 1910.269(d)(8)(v), 1910.146, 1910.147
Response to Exelon Generation's concerns regarding draft Instruction CPL 2-1.18A, "Enforcement of the Electric Power Generation, Transmission and Distribution Standard." 1910.269, 1910.269(d), 1910.269(d)(8)(v), 1910.147
Clarification on the USPS's lockout/tagout procedures and minor servicing operations for the multiple line optical character recognition sorter. 1910.147, 1910.147(a)(2)(ii)
Acceptability of modifying a standard on/off switch to provide lockout capability to a machine. 1910.147, 1910.147(c)(3), 1910.147(c)(2)(iii), 1910.303(a), 1910.399, 1910.303
Requirements for developing sufficiently-detailed written procedures for all machinery/equipment lockout/tagout. 1910.147(c)(4)(ii), 1910.147(d)(1), 1910.147
Applicability of the confined-space standard to dock-leveler pits. 1910.146, 1910.146(b), 1910.146(c)(7), 1910.146(c)(7)(i), 1910.146(c)(7)(ii), 1910.146(c)(7)(iii), 1910.146(c)(7)(iv), 1910.147
Color is not the only prescribed factor for the standardization of LOTO devices. 1910.147, 1910.147(c)(5)(ii)(B)
Use of verification tags for lockout. 1910.147, 1910.147(c)(5), 1910.333
Guidance on approval requirments for general circuit breaker panel swich lockouts in General Industry. 1910.305(b)(2), 1910.147(c)(5), 1910.303(g)(2)(ii)
Scenario of a tool change process applied to Lock Out/Tag Out's service and maintenance exception. 1910.147(a)(2)(ii)
Coverage of minor machine-servicing activities under the Lockout/Tagout standard. 1910.147(a)(2)(ii), 1910.147(a)(2)(iii)(A)
Authorized employees must have the opportunity to verify energy isolation in group lockout/tagout 1910.269(d), 1910.147(c)(2), 1910.147(d)
Required components of a LOTO inspection. 1910.147(c)(6), 1910.147(c)(7)
Applicability of OSHA's LOTO standards; isolation and verification procedures. 1910.147, 1910.333(b), 1910.399