Understanding OSHA 1910.147
OSHA standard 29 CFR 1910.147 establishes the baseline requirements for controlling hazardous energy during the servicing and maintenance of machines. If an unexpected energization or start-up could occur and cause injury, the equipment must be locked out.
While companies must have a generalized corporate energy control program, the law also requires granular, step-by-step procedures for each individual piece of equipment that has multiple energy sources.
Who Needs Machine-Specific Procedures?
The rule of thumb is that if a machine has more than one energy source (e.g., electrical plus pneumatic), it requires its own written procedure. You cannot rely on a generic factory-wide guideline.
OSHA does offer a strict exemption. A documented procedure is not required if a machine has exactly one singular energy source that can be easily identified and isolated, and locking out that one source completely de-energizes the machine with no potential for stored energy.
Key Elements of a Compliant LOTO Procedure
A machine-specific LOTO procedure must be explicit. It must guide authorized employees through a safe and repeatable process. Ambiguity in these steps leads to fatal mistakes.
The document must list the specific types and magnitudes of energy present, as well as the exact location of the isolation devices (such as breaker panels or valves).
- Scope and Purpose: Identify the exact machine and the intended use of the procedure.
- Shutdown Steps: The chronological sequence for safely turning the machine off.
- Isolation Steps: Specific instructions on where and how to apply locks and tags to valves, breakers, or disconnects.
- Stored Energy Relief: Instructions to bleed, block, or safely dissipate residual energy (e.g., bleeding air pressure or blocking elevated parts).
- Verification Steps: The critical final step to physically test the controls and confirm the machine will not start.
Annual Inspection and Verification
OSHA requires that all machine-specific energy control procedures be inspected at least annually. This ensures the procedure is still accurate and that employees understand how to execute it.
The inspection must be performed by an "authorized employee" other than the ones currently using the energy control procedure being inspected. The inspector must document the date, the equipment, and the employees involved.
Frequently asked questions
What types of hazardous energy must be isolated?
Hazardous energy includes electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and gravity (potential energy).
Can I use one procedure for identical machines?
Yes, if multiple machines are the exact same make and model and have identical energy control setups, one written procedure can cover all of them, provided their physical locations and disconnects are clearly marked.
What is the difference between an Authorized and Affected employee?
An 'Authorized' employee is trained to apply the lock and perform the maintenance. An 'Affected' employee operates the machine or works in the area but does not perform the servicing.
Why is the verification step so important?
Verification, or 'Try Out', confirms that the correct isolations were made and no residual energy remains. Skipping this step is a leading cause of LOTO-related accidents.