Lockout/Tagout (LOTO)

Lockout/tagout protects you from machines and equipment that start up unexpectedly, or release stored energy, while you service, repair, clean or unjam them. Failing to control hazardous energy causes many amputations, crushing injuries and electrocutions every year, and lockout is one of OSHA’s most-cited standards.

• General Industry
• Construction
• Maintenance

Types of hazardous energy

Many machines have more than one energy source. A press may have electrical, hydraulic, pneumatic and gravity energy all at once. Every source must be controlled.

When lockout is required

In general industry, lockout applies whenever workers service or maintain machines or equipment where unexpected startup or release of energy could hurt them. That includes when a worker must:

• Remove or bypass a guard or other safety device
• Put any part of their body where it could be caught by moving parts (the point of operation or danger zone)
• Clear jams, clean, lubricate, adjust, set up or change tooling

Exceptions are narrow:

• Cord-and-plug equipment when it’s unplugged and the plug stays under the exclusive control of the worker doing the service.
• Minor servicing during normal production (such as quick tool changes), but only if the employer uses other effective protection such as special tools or interlocked guards.
• Hot tap work on pressurized pipelines, under strict special procedures.

In construction, OSHA requires lockout and tagging of electrical circuits, and many contractors follow the general industry lockout rule for all equipment as best practice.

Who’s who

• Authorized employee: trained to lock out machines and perform the service work. Only authorized employees apply locks.
• Affected employee: operates or works near the equipment. They must be told about the lockout and must never try to restart locked-out equipment.
• Other employees: anyone else in the area. They must be trained to recognize lockouts and leave them alone.

The energy control program

Employers must have a written program that includes:

• Written procedures for each machine or type of equipment, listing every energy source, how to isolate it, how to release stored energy, and how to verify.
• Training for authorized, affected and other employees, with retraining when equipment, procedures or jobs change, or when an inspection shows problems.
• Periodic inspections of each procedure, at least once a year, by an authorized employee who isn’t using that procedure.
• Lockout devices provided by the employer.

Locks and tags

• Locks must be used only for lockout, be durable and standardized (by color, shape or size), and identify the person who applied them.
• Each authorized employee gets their own personal lock and keeps the only key.
• Tags must warn against energizing (for example, “DO NOT START,” “DO NOT OPERATE”), identify who applied them, and be attached with a non-reusable, self-locking tie strong enough to withstand at least 50 pounds.
• Use the right lockout device: breaker locks, plug lockouts, ball and gate valve covers, and group lockout hasps.

The lockout steps

1. Prepare: read the written procedure. Know every energy source, where the isolation points are, and how to verify.
2. Notify affected employees that the machine is being shut down and locked out, and why.
3. Shut down the equipment using its normal stopping procedure.
4. Isolate every energy source: open disconnects, close valves, disconnect lines, insert blanks. Don’t rely on control circuits, push buttons or interlocks; they aren’t energy-isolating devices.
5. Apply your lock and tag to each isolation point. Every worker who will be exposed applies their own personal lock.
6. Release or restrain stored energy: bleed pressure, block raised parts, release springs, discharge capacitors, let parts coast to a stop, and drain lines. If stored energy could build back up, keep checking it.
7. Verify zero energy: make sure everyone is clear, then try to start the machine with its normal controls. Return the controls to off. For electrical work, a qualified person tests for absence of voltage with a meter, testing the meter on a known live source before and after (live-dead-live).
8. Do the work.
9. Restore: remove tools and materials, put all guards back, make sure everyone is clear and accounted for, tell affected employees the machine is being restarted, and then each person removes only their own lock and tag.

Verification is the step people skip

Many lockout injuries happen because someone locked out the wrong disconnect, missed a second energy source, or assumed stored pressure was gone. Always verify:

• I tried the start button or control, and nothing moved
• Gauges read zero, and lines are bled
• Raised parts are lowered or blocked
• Electrical circuits tested dead with a working meter
• I checked for a second power source, backup battery or interconnected equipment
• I returned all controls to off after testing

Group lockout

When a crew works on the same equipment, use a group lockout device or lockbox:

• One primary authorized employee locks out the equipment and puts the keys in a lockbox.
• Each worker puts their personal lock on the lockbox or group hasp before starting work.
• The equipment can’t be re-energized until every worker removes their lock.
• Workers keep their lock on until they personally are done and clear.

Shift changes and contractors

• Shift changes: the employer must have a procedure to keep lockout protection continuous, such as the oncoming worker applying their lock before the outgoing worker removes theirs.
• Outside contractors: the host employer and the contractor must tell each other about their lockout procedures, and each must make sure their workers follow them.
• Testing or positioning: if equipment must be powered briefly to test or adjust it, follow the procedure: clear tools, remove people, remove locks in order, energize and test, then de-energize and lock out again before continuing work.

Tags alone

A tag is a warning, not a physical barrier. Tagout alone is allowed only when an energy-isolating device truly can’t be locked, and then the employer must provide the same level of safety as a lock, for example by removing a fuse, blocking a switch, or opening an extra disconnect. Equipment installed or modified since 1990 must be designed to accept a lock.

Last updated: October 1, 2026