What is lockout/tagout (LOTO)?
Lockout/tagout is putting a lock, a tag or both on the device that controls a machine's energy, so the machine cannot start or release stored energy while someone works on it.
Also called LOTO, control of hazardous energy
What it means.
OSHA's standard is titled The control of hazardous energy (lockout/tagout), 29 CFR 1910.147. It covers servicing and maintenance where the unexpected energization or start up of machines or equipment, or the release of stored energy, could injure employees. Lockout is placing a lockout device on an energy isolating device; tagout is placing a warning tag on one.
An energy isolating device physically stops energy from reaching the equipment, such as a disconnect switch, a line valve or a block. Push buttons, selector switches and other control circuit type devices are not energy isolating devices. The employer needs an energy control program made up of energy control procedures, employee training and periodic inspections. Construction and agriculture employment are outside this general industry standard.
Push buttons, selector switches and other control circuit type devices are not energy isolating devices.
Where it shows up on a job.
Before clearing a jam inside a packaging machine, the mechanic shuts it down, isolates the power and air, puts a personal lock and tag on each isolation point, releases stored energy, and tries the controls to confirm nothing moves.
Where this comes from.
Each source was read on 22 October 2026. Guidance is advice; a regulation is the rule.
- 29 CFR 1910.147Code of Federal Regulations, Title 29. Regulation. Scope, definitions and the energy control program.
- Control of Hazardous Energy (Lockout/Tagout)Occupational Safety and Health Administration. OSHA guidance, advisory. OSHA's overview of the standard.
A plain-language definition, not legal advice. For a decision on your site, read the standard that applies to it.
Related terms
- permit to work
A permit to work is a written authorization, signed by someone allowed to sign it, for a specific hazardous job to go ahead under named controls for a set period.
- safety inspection
A safety inspection is a planned look at a workplace, a job, equipment or a procedure, done to find hazards before they cause harm.
- confined space
A confined space is a space large enough for a person to enter and work in, with limited or restricted ways in and out, that is not designed for someone to stay in.
- hazard
A hazard is anything at work that can hurt someone if it is not controlled: a condition, a task, a chemical or a source of energy.