Lockout tagout (often abbreviated LOTO) is a safety procedure that ensures dangerous machines and equipment are properly shut down and cannot restart while someone is working on them. It involves placing physical locks and warning tags on energy controls so that equipment stays off during maintenance or repair. LOTO is required by federal workplace safety law and applies to any situation where an unexpected machine startup or energy release could injure a worker.
How Lockout Tagout Works
Every piece of industrial equipment runs on some form of energy, whether that’s electricity powering a motor, compressed air driving a piston, or hydraulic fluid holding a press in position. When a worker needs to service that equipment, simply hitting the “off” switch isn’t enough. Switches can be bumped, circuits can be tripped, and stored energy can release without warning. LOTO adds a physical barrier that makes accidental restart impossible.
The “lockout” part means placing a padlock on the device that controls energy flow, such as a circuit breaker, disconnect switch, or line valve. With the lock in place, nobody can flip the switch or open the valve. The “tagout” part means attaching a standardized label to that same device. The tag identifies who locked the equipment, when they did it, and why. Together, the lock physically prevents the machine from restarting and the tag communicates to everyone nearby that maintenance is in progress.
Types of Hazardous Energy
LOTO isn’t just about electricity. OSHA identifies several categories of hazardous energy that all require lockout tagout controls:
- Electrical: current flowing through wiring, motors, and control panels
- Mechanical: energy stored in springs, flywheels, or rotating parts that can move even after power is cut
- Hydraulic: pressurized fluid in lines and cylinders that can release force suddenly
- Pneumatic: compressed air or gas in tanks and lines
- Thermal: extreme heat or cold retained in equipment, pipes, or tanks
- Chemical: stored substances that can react, release fumes, or cause burns
A single machine can have multiple energy sources. A hydraulic press, for example, has both electrical energy running its controls and hydraulic energy holding the ram in position. Every source must be individually isolated and locked out before work begins, and any stored energy has to be safely released or restrained.
The Step-by-Step Procedure
OSHA requires employers to develop a written LOTO procedure for each piece of equipment. While the specifics vary by machine, every procedure follows the same general sequence.
Shutting Down and Locking Out
First, the authorized worker notifies all affected employees that the equipment is about to be shut down and explains why. Then they power the machine down using its normal stopping procedure. After shutdown, they locate every energy isolating device for that equipment, such as circuit breakers, valves, or disconnects, and move each one to the “off” or “closed” position. The worker places their personal lock on each isolating device, then attaches a tag that includes their name, the date and time, and the reason for the lockout.
Next comes a critical step that’s easy to overlook: releasing or restraining any stored energy. Even after you flip a breaker, a capacitor can hold a charge, a spring can stay compressed, and fluid in a hydraulic line can still be under pressure. The worker must bleed lines, discharge capacitors, block raised components, or take whatever other steps are needed to bring stored energy to zero.
Finally, the worker verifies the lockout by attempting to start the equipment through its normal controls. If nothing happens, the machine is confirmed safe to work on.
Removing Locks and Restarting
When the work is done, the process reverses in a specific order. The worker inspects the area to make sure all tools and materials have been removed. They confirm that every coworker is clear of the machine and any hazardous areas around it. They check that all operating controls are in a neutral position. Then they remove the lockout and tagout devices in the reverse order they were installed and re-energize the equipment. Affected employees are notified that the machine is back in service.
Only the worker who applied a lock is authorized to remove it. This is a core safety principle: your lock, your key, your life.
Requirements for Locks and Tags
LOTO devices aren’t ordinary padlocks and labels grabbed from a supply closet. OSHA sets specific requirements for the hardware used in lockout tagout programs.
Locks and tags must be used exclusively for energy control and never repurposed for other uses like securing a toolbox. They must be standardized across a facility by color, shape, or size so workers can instantly recognize them. Each device must identify the specific employee who applied it.
Locks need to be substantial enough that they can’t be removed without bolt cutters or similar metal-cutting tools. Tags and their attachment straps must withstand the environment they’re used in, including exposure to weather, moisture, and corrosive chemicals, without deteriorating or becoming unreadable. The attachment mechanism for tags must be non-reusable, self-locking, and strong enough to resist at least 50 pounds of pulling force. Think heavy-duty nylon cable ties rather than twist ties or string.
Who Needs LOTO Training
OSHA’s standard draws a clear line between two groups of workers. “Authorized” employees are the ones who actually perform the lockout tagout. They need detailed training on how to identify hazardous energy sources, how to apply and remove LOTO devices, and the specific procedures for every machine they work on. “Affected” employees are people who operate or work near the equipment but don’t perform the maintenance. They need to understand the purpose of LOTO and know that they must never attempt to restart locked-out equipment or remove someone else’s lock or tag.
Training must be repeated whenever job assignments change, when new equipment or procedures are introduced, or when an employer has reason to believe workers aren’t following proper procedures. Employers are also required to conduct periodic inspections of their LOTO program at least once a year to make sure procedures are being followed correctly.
What the Law Requires
OSHA’s lockout tagout standard (29 CFR 1910.147) covers the servicing and maintenance of machines and equipment where unexpected energization or the release of stored energy could injure workers. It applies to general industry workplaces and sets minimum performance requirements for hazardous energy control programs.
Employers must develop, document, and implement energy control procedures. They must provide all necessary LOTO hardware. They must train workers and conduct annual inspections. Lockout tagout violations consistently rank among OSHA’s most frequently cited standards, which reflects how common noncompliance is across industries.
The financial penalties are significant. As of January 2025, a serious violation can result in a fine of up to $16,550 per occurrence. Willful or repeated violations carry penalties up to $165,514 each. Failure to correct a violation after being cited can cost $16,550 per day. Beyond fines, a LOTO failure that leads to a worker injury or death can result in criminal prosecution and civil liability far exceeding those amounts.
When LOTO Applies
LOTO is required whenever a worker performs servicing or maintenance where they could be exposed to hazardous energy. This includes tasks like clearing jams, cleaning internal components, adjusting machinery, replacing parts, and lubricating equipment. It applies whether the work is routine maintenance or a one-time repair.
There are limited exceptions. Minor tool changes and adjustments that are routine, repetitive, and integral to normal production may be exempt if the employer provides alternative effective protection. Normal production operations where workers only interact with machines through their standard controls, and where guards and safety devices provide adequate protection, also fall outside the standard’s scope. But the moment a worker bypasses a guard, reaches into a danger zone, or works on a part of the machine that could unexpectedly move or energize, LOTO procedures apply.