DEFINITION
Lockout/Tagout (LOTO) is the OSHA-required practice of isolating and de-energizing machinery so it cannot start up during service or maintenance. Under 29 CFR 1910.147, each energy-isolating device is locked and tagged, protecting workers from the unexpected release of hazardous energy.
ALSO KNOWN AS · lockout tagout · energy control · OSHA 1910.147 · LOTO
29 CFR 1910.147, 'The Control of Hazardous Energy (Lockout/Tagout),' protects workers servicing or maintaining machines from the unexpected energization, start-up, or release of stored energy. The standard requires an energy-control program with written procedures, employee training, and periodic inspection. 'Lockout' means physically locking each energy-isolating device in the safe position; 'tagout' means attaching a prominent warning tag where a lock cannot be applied.
A LOTO procedure follows a defined sequence: notify affected employees, shut down the equipment, isolate all energy sources (electrical, hydraulic, pneumatic, mechanical, thermal, gravity), apply individual locks and tags, release or restrain stored energy (bleed hydraulic pressure, block suspended parts, discharge capacitors), and then verify zero energy state by attempting to start the equipment before any work begins. Each authorized employee applies their own lock, and only that person removes it.
LOTO is the energy-control mechanism that makes equipment safe to inspect, repair, or service. It connects directly to inspection workflows: when an inspection reveals a defect that must be corrected, the equipment is locked out so a mechanic can work on it safely, and it stays out of service until the repair is verified.
The standard also requires a periodic inspection of the energy-control procedure itself, at least annually, by an authorized person other than the one using the procedure — a meta-inspection confirming the LOTO program is being followed correctly.
AUTHORITATIVE · SOURCE
29 CFR 1910.147 — The control of hazardous energy (OSHA.gov)FREQUENTLY · ASKED
Lockout physically locks an energy-isolating device in the safe (off) position so it cannot be operated. Tagout attaches a warning tag where a lock cannot be applied. OSHA prefers lockout; tagout alone is allowed only when the device cannot accept a lock and equivalent protection is provided.
After isolating and locking out all energy sources and releasing stored energy, you verify by attempting to operate the equipment's normal start controls (then returning them to off). Only after confirming it will not start does service work begin.
RELATED · TERMS
A red tag marks equipment as out of service and unsafe to operate until a defect is corrected. When an inspection finds a safety-affecting deficiency, the equipment is red-tagged and removed from service so no one can use it before the repair is verified.
An OSHA competent person is someone capable of identifying existing and predictable hazards in the surroundings or working conditions that are unsanitary, hazardous, or dangerous to workers, AND who has authorization to take prompt corrective measures to eliminate them.
OSHA 1910.178 is the powered-industrial-truck standard covering forklifts and similar trucks. Section 1910.178(q)(7) requires that each truck be examined at least daily before being placed in service, and removed from service if any condition adversely affects safety.
A preventive maintenance (PM) inspection is a scheduled check performed on a calendar interval or usage trigger (engine hours, mileage, cycles) to service equipment and catch wear before it causes failure — distinct from a regulatory safety inspection, though the two are often combined.
PUT · IT · TO · WORK
DigiDocs ships free inspection checklists built to OSHA, FMCSA, ASME, and ANSI. Download the PDF, or run it digitally on any phone — photo capture on failures, automatic deficiency logging, and a signed audit-trail record.