October 24, 2005

Mr. Jimmy Hill
Safety and Mission Assurance Directorate
Industrial Safety Department
Marshall Space Flight Center
Huntsville, AL 35812

Dear Mr. Hill:

Thank you for your inquiry dated May 24, 2005, regarding clarification of the definition for "Readily accessible" as contained in the Occupational Safety and Health Administration's (OSHA) electrical standards. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any question not delineated within your original correspondence. We apologize for the delay in our response. Your paraphrased scenario, question, and our response are provided below.

Scenario: It is not a standard practice at the Marshall Space Flight Center to lock electrical panels operating at 600 volts or less, but a request has been received from our Facilities Department to place locks that require a key to open all electrical panels. Locking the panels is to control access by unauthorized employees. A majority of these panels are lighting panels operating at 277 volts and are located throughout the center in office buildings, shop areas, and testing facilities. The breakers in these electrical panels are not used by employees as switches to turn equipment on and off daily.

Question: Does locking the electrical panels operating at 600 volts or less (to control access by unauthorized employees) violate OSHA electrical requirements for not being "Readily accessible" in the event of an emergency?

Response: In accordance with 29 CFR 1910.399, Readily accessible is defined as "capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc." This definition, however, does not preclude the use of a lock on the disconnecting means (circuit breakers panel), provided those, for whom ready access may be necessary, have a key (or lock combination) available. Additionally, the National Electrical Code (NEC) 2005, Article 110.26, partly states, "Enclosures housing electrical apparatus that are controlled by a lock(s) shall be considered accessible to qualified persons." Please note that the use of multiple locks, which requires different keys or combinations, on disconnecting switches may preclude the installation from being accessible or readily accessible to a particular individual who is authorized to access the panel.

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. 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 www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Enforcement at 202-693-1850.

Sincerely,



Richard E. Fairfax, Director
Directorate of Enforcement Programs