Electrical guarding threshold for direct-current equipment

September 4, 2015

Mr. Mark Duvall, Esq., Principal

Beveridge & Diamond

[Recipient address omitted]

Dear Mr. Duvall:

Thank you for your March 19, 2015 correspondence to the Occupational Safety and Health Administration (OSHA), Directorate of Enforcement Programs. You requested clarification of how OSHA’s energized electrical equipment guarding standard applies to the protection level for direct current (DC).

Scenario: You requested an interpretation of how 29 CFR 1910.303(g)(2)(i) applies to guarding exposed equipment operating at 50 volts or more direct-current (DC). You indicated that some national consensus standards consider exposed equipment operating at up to 60 volts DC, as safe. NFPA and UL consider unguarded equipment operating at 60 volts or less DC, to be safe (although with stipulations, such as, only for specific equipment applications; the employees skin is un-broken; assumed dry conditions, etc.). You suggest that if employers follow the consensus standard, with respect to dc, they should receive a de minimis violation for electrical guarding.

Question 1: Does the electrical guarding requirement in 29 CFR 1910.303(g)(2) apply to voltages below 60 volts DC?

Response: The requirement in 29 CFR 1910.303(g)(2) does not distinguish between ac or dc. OSHA regulations require guarding live parts operating at 50 volts or more, irrespective of AC or DC, or frequency (hertz) measureable.

Question 2: If an employer does not guard energized equipment at voltages below 60 volts DC, would OSHA consider it a de minimis violation?

Response: No, by definition a de minimis violation can be found when an employer varies from the requirements in the standard, and such variation has no direct or immediate relationship to employee safety or health; or complies with consensus standards instead of OSHA regulations, and the consensus standard clearly provides equal or greater employee protection. Changing the protection levels for direct current has a direct impact on employee safety due to increased shock hazard, and therefore could not be a de minimis violation.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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. If you have any further questions, please feel free to contact the Directorate of Enforcement Programs at (202) 693-2100.

Sincerely,

Thomas Galassi, Director

Directorate of Enforcement Programs