Lockout/Tagout (LOTO) Basics

Lockout/tagout, commonly shortened to LOTO, is the set of procedures that keep equipment from starting up unexpectedly or releasing stored energy while someone is servicing it. It's governed in the United States by OSHA standard 29 CFR 1910.147 for general industry, with a parallel construction requirement under 1926.417, and it consistently lands in OSHA's top ten most-cited standards every year. Properly isolating a circuit means locking out the disconnect switch or circuit breaker that feeds the equipment, not just switching it off. This guide covers what LOTO requires, the six-step procedure OSHA prescribes, the types of hazardous energy it controls, and the mistakes that most often draw citations.

What Triggers a LOTO Requirement

OSHA's test is straightforward: if a machine could start on its own, or stored energy could be released and harm someone during servicing or maintenance, lockout/tagout applies. That covers the majority of repair and setup work, clearing jams, removing or bypassing machine guards, and working inside electrical enclosures. A narrow exception exists for minor tool changes and adjustments that are routine, repetitive, and integral to production, but the standard's default assumption is that LOTO is required unless a documented exception clearly applies.

Lockout vs. Tagout: Not Interchangeable

The two terms describe different levels of protection, and OSHA does not treat them as equally acceptable substitutes:

• Lockout physically secures an energy-isolating device, a circuit breaker, valve, or disconnect switch, in the safe position with a padlock, so the device cannot be operated at all until the lock is removed.
• Tagout attaches a warning tag to the isolating device, but a tag alone does not physically block operation; it only communicates that the device should not be used.

OSHA's default rule is lockout whenever the device is capable of accepting a lock. Tagout alone is only permitted when the device physically cannot accept a lock, and even then, the employer must demonstrate that the tagout program provides protection equal to lockout, typically through additional measures like removing a circuit element or adding an extra disconnect.

The Seven Types of Hazardous Energy

A complete LOTO procedure has to account for every form of energy present at the equipment, not just the obvious electrical feed:

• Electrical (line power, capacitor stored charge, batteries)
• Mechanical (springs, flywheels, counterweights)
• Hydraulic (pressurized fluid in cylinders or lines)
• Pneumatic (compressed air in lines or accumulators)
• Chemical (reactive or hazardous process materials)
• Thermal (hot surfaces, steam, or extreme cold)
• Gravitational (raised components that could fall)

A common inspection finding is a worker who isolates the electrical feed but overlooks a pneumatic line or a hydraulic accumulator holding stored pressure; a compliant procedure addresses every energy source present, not just the most visible one.

The Six-Step LOTO Procedure

Verification is the step most often skipped in practice and one of the most frequently cited violations; skipping it means the crew is trusting that isolation worked rather than confirming it did.

Group Lockout and Multiple Workers

When more than one person needs to work on the same equipment, a hasp lets each authorized employee attach their own individual lock to a single isolation point. The equipment stays locked out until the very last person removes their own lock, and no one is permitted to remove a lock that isn't theirs. This rule is treated as absolute under 1910.147; a supervisor removing another worker's lock, even with good intentions, is a serious violation.

Removing LOTO Devices When Work Is Complete

• Inspect the work area to confirm all tools have been removed and equipment components are intact.
• Verify that all employees are safely clear of the equipment.
• Each employee removes only their own lock or tag.
• Notify affected employees that servicing is complete and the equipment is about to be re-energized.

Common LOTO Violations

• No machine-specific written procedures: a generic, facility-wide LOTO program without documented steps for each piece of equipment is the single most common finding in OSHA inspections.
• Failing to address every energy source: isolating electrical power while ignoring a pneumatic or hydraulic line is a frequent gap inspectors specifically test for.
• Using a tag where a lock would fit: tagout alone on a device capable of accepting a lock, without documented equivalent protection, violates the standard's lockout preference.
• Skipping verification: proceeding to work without confirming a true zero-energy state defeats the purpose of the entire procedure.
• Inadequate training: authorized, affected, and other employees each need training scoped to their role, and retraining is required whenever job assignments, equipment, or procedures change.

The Bottom Line

Lockout/tagout exists because unexpected startup or stored-energy release during servicing is one of the most preventable causes of serious workplace injury, and OSHA 1910.147 estimates the standard prevents roughly 120 fatalities and 50,000 injuries every year when followed correctly. The core of a compliant program is straightforward: identify every energy source at the equipment, physically lock out each isolating device rather than relying on a tag alone, relieve any stored energy, and verify a true zero-energy state before work begins. The violations that draw the most citations almost always trace back to skipping one of those steps, not to unusual or exotic equipment.