Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

March 4, 1977

Mr. James Wolf Manager,
Government Relations
The Trane Company
2020 14th Street
North Arlington, Virginia 22201

Dear Mr. Wolf:

This is in response to your letter dated February 4, 1977, and confirms the telephone conversations with Harold Gier, Safety Specialist, Division of Occupational Safety Programming, concerning machinery and machine guarding.

In answer to your first question; the intent of 29 CFR 1910.212(a)(5), fan blade guarding requirement, is to prevent an employee from coming into contact with a blade and the size opening in the guard is dependent on the distance between the blade and the guard. This standard was intended to apply only to fans used for employee comfort cooling.

The standard was not intended to apply to fans that are an integral part of a unit such as cooling towers, air handling units, or in closed ventilating systems. However, fans of the latter type are required to be guarded in accordance with 29 CFR 1910.212(a)(1), as rotating parts. The guidelines for the construction of the guards are found in paragraphs (m) and (o) of 29 CFR 1910.219 using Table 0-12 to determine material, distance and size of openings required.

In answer to your second question; the primary concern of "enclosed" and "fully enclosed" is to prevent employees from injuries by moving belts, taking into consideration guarding by location. Enclosed on vertical and inclined belts means that only that part of the belt less than seven (7) feet from the floor must be guarded, while any other part of the belt over seven (7) feet may remain exposed. Full enclosure of horizontal belts with both runs less than 42 inches above the floor is required, meaning all exposed sides including the full length of the belts. A full length, three-sided guard is considered as meeting the intent of the standard as long as the fourth side is guarded by location.

Hopefully, this information will be helpful. If I may be of any further assistance, please feel free to contact me.


John K. Barto,
Chief Division of
Occupational Safety Programming