What does “Lockout/tagout” mean?
Short answer
Lockout/tagout (LOTO) means cutting a machine's power and locking or tagging the switch before repairs. OSHA's standard is 29 CFR 1910.147.
Also known as: LOTO, control of hazardous energy, 29 CFR 1910.147
What the standard requires
29 CFR 1910.147 covers service and repair of machines where a sudden start-up, or release of stored energy, could hurt workers. The employer must run an energy control program with three parts: procedures, training and inspections.
- Use lockout if the energy device can be locked, unless tagout gives full protection.
- Use tagout where the device cannot be locked. A tag is a warning, not a block.
- Inspect each procedure at least yearly.
- The inspector must be an authorized employee (one trained to lock out machines) who does not use it.
- Train authorized employees on energy sources and shutoff steps. Tell other employees about the procedures.
Scope and an example
The standard does not cover construction, agriculture, some maritime work, power utilities, electrical hazards under subpart S, or oil and gas well work. Normal production is covered only when, for example, a guard is removed or bypassed.
Example: a technician clearing a jam on a packaging line shuts the line down, locks the breaker, adds a personal tag and checks that the line cannot start before reaching in. A LOTO failure with no injury is a PSIF-type event that needs investigation.
Mix-up: LOTO applies to service and repair, not every machine stop, and a tag alone does not stop energy. It is one control among many on the hierarchy of controls.
Frequently asked questions
How often must lockout/tagout procedures be inspected?
At least yearly, by an authorized employee who does not use the procedure. The inspection must fix any gaps. For lockout, the inspector also reviews duties with each authorized employee.
Does 29 CFR 1910.147 apply to construction?
No. It excludes construction and agriculture, plus some maritime work, utility installations and a few other types. Check the construction standards instead.
Is tagout alone acceptable?
Only where the device cannot be locked out, or where the employer shows tagout gives full protection. Lockout is the default when the device can be locked.
Sources
Reviewed against the sources above on Oct 5, 2026. Rules change: confirm current requirements with the issuing body or your counsel before relying on any summary.
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