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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

July 18, 1995

Ms. Katherine G. Hammack
Senior Product Manager
Carrier Corporation
P.O. Box 25000
100 Murphy Drive
Maumelle, AR 72113

Dear Ms. Hammack:

This is in response to your letter of February 2, 1995, regarding interpretations of OSHA's Standards as they apply to air-conditioning units.

Your letter referenced and summarized 29 CFR 1910.219, "Mechanical Power-Transmission Apparatus," and indicated that you are aware of specifications that ask for the belts to be guarded in accordance with OSHA standards, however, you were not able to locate a provision requiring the guarding of belts in 1910.219. The appropriate standard to reference would be 29 CFR 1910.212, "General Requirements for all Machines."

Section 29 CFR 1910.212 requires that all machines be provided with guards to protect the operator and other employees against injuries.

It was stated in your letter, "Since air handler fans are totally enclosed in a `solid sheet metal' cabinet, we feel that our standard design more than meets the OSHA standard for belt guarding." Your assessment with regard to the "solid sheet metal" cabinet being sufficient is correct, so long as this cabinet remains in place and is not removed for service and maintenance tasks.

During the performance of any maintenance service which would require the removal of the cabinet or the opening of access doors, it is imperative that employees performing the maintenance be provided protection against contacts with any moving components of the system (e.g., fan belts, pulleys, shafts, belts, etc.). Employees' protection could be achieved by the following means:

(a) either by deenergizing the system according to 1910.147(d) (disconnecting power) before removing the "solid sheet metal" cabinet, and reenergizing (reconnecting power), only after the servicing is completed and the cabinet is placed into its original position, or, (b) if the servicing requires that the system be in running status, for any portion of the maintenance operation, then separate guarding for all moving parts (e.g., blades, shafts, pulleys, etc.), must be provided, according to 1910.212. Alternatively, the sequence of actions described in 1910.147(f) for testing or positioning of machines, equipment and components thereof must be followed.

Thank you for your interest in occupational safety and health. If you need further assistance, please contact Alcmene Haloftis of my staff, on 202-219-8031, Ex. 119.

Raymond E. Donnelly, Director
Office of General Industry Compliance