Lock Out Tag Out (LOTO) Procedures: The Complete Guide

A machine that starts unexpectedly while someone is inside it, under it, or reaching into it will kill or maim that person. Lock Out Tag Out exists to make sure that never happens.

LOTO is not complicated. You isolate every energy source, lock it in the off position, verify the energy is gone, and keep control of the key until the work is finished. The concept is simple. The execution is where companies fail - and where workers get hurt.

This guide covers everything you need to build, implement, and maintain LOTO procedures that actually protect your workers.

What Is LOTO (Lock Out Tag Out)?

Lock Out Tag Out is a safety procedure that ensures hazardous energy sources are properly isolated and de-energized before maintenance or servicing work begins on equipment.

Lock Out: A physical lock is placed on an energy isolation device (breaker, valve, disconnect switch) to prevent it from being turned on. Only the person who placed the lock has the key.

Tag Out: A tag is attached to the lock or isolation device identifying who locked it out, why, and when. The tag communicates to everyone: do not touch this.

Together, they create a system where equipment cannot be accidentally or intentionally energized while someone is working on it.

Why LOTO Matters: The Numbers

OSHA estimates that compliance with LOTO standards prevents approximately 120 fatalities and 50,000 injuries every year in the United States alone. The standard (29 CFR 1910.147) consistently ranks among OSHA's most-cited violations.

Failures are almost never mechanical. Locks work. The failures are procedural:

• Someone assumed the machine was off without verifying
• A second energy source was missed
• Someone removed another worker's lock
• The procedure existed on paper but nobody followed it

Every one of these is preventable with proper training and enforcement.

Types of Hazardous Energy

LOTO applies to ALL forms of hazardous energy, not just electrical. This is where many programs fall short - they lock out the breaker and forget about everything else.

Electrical: The most obvious. Circuits, motors, control panels, battery systems.

Mechanical: Stored energy in springs, flywheels, rotating parts that coast after power is cut.

Hydraulic: Pressurized fluid in cylinders, lines, and accumulators. A hydraulic line at 3,000 PSI will cut through skin like a knife.

Pneumatic: Compressed air in tanks, lines, and cylinders. Residual pressure can drive a piston with lethal force.

Thermal: Hot surfaces, steam lines, molten materials, cryogenic systems. Energy stored as heat does not dissipate when you flip a switch.

Chemical: Hazardous materials in pipelines, tanks, and process vessels. Isolation may require blanking or double-block-and-bleed.

Gravitational: Suspended loads, raised platforms, elevated machine components. Anything that can fall when a support is removed.

If your LOTO procedure only addresses electrical energy, your workers are exposed to every other source on this list.

LOTO Procedure: Step by Step

Step 1: Preparation

Before touching anything:

• Identify the equipment to be locked out
• Identify ALL energy sources (use the equipment-specific LOTO procedure)
• Identify ALL isolation devices (breakers, valves, disconnects, blocks)
• Notify all affected employees that the equipment will be shut down
• Gather your locks, tags, and any blocking/blanking devices needed

Step 2: Shutdown

Shut down the equipment using normal operating procedures. Do not just pull the plug - follow the proper shutdown sequence to avoid creating additional hazards.

Step 3: Isolation

Physically isolate all energy sources:

• Open electrical disconnects
• Close and lock valves
• Block or blank pipelines
• Engage mechanical blocks or pins
• Relieve stored energy (bleed pressure, release springs, lower suspended parts)

Step 4: Lock Out and Tag Out

Apply your personal lock to each isolation device. Attach a tag that includes:

• Your name
• Your department or contact information
• Date and time of lock application
• Reason for the lockout
• Expected duration

One worker, one lock, one key. Never share locks. Never give someone else your key.

Step 5: Verify Zero Energy State

This is the step people skip. It is the step that kills them.

• Try to start the equipment using normal controls (it should not start)
• Test electrical circuits with a voltage tester (verify the tester works before and after)
• Check pressure gauges for hydraulic and pneumatic systems (should read zero)
• Verify mechanical components are at rest and blocked
• Check thermal conditions if applicable

Verification must be done by the person doing the work. Do not take someone else's word for it.

Step 6: Perform the Work

With all energy sources isolated, locked, tagged, and verified - proceed with the maintenance or servicing work.

Step 7: Removal

When work is complete:

• Remove all tools and materials from the equipment
• Replace all guards and safety devices
• Verify all workers are clear of the equipment
• Remove your lock and tag (only the person who placed them)
• Notify affected employees that the equipment is being returned to service
• Restore energy and test the equipment

Group LOTO Procedures

When multiple workers service the same equipment, group LOTO adds coordination requirements:

Option 1: Individual Locks
Every authorized worker places their own lock on every isolation device. Equipment cannot be energized until every lock is removed. This is the safest method but requires enough lockout points for all workers.

Option 2: Lock Box
All isolation device keys go into a lock box. Each worker places their personal lock on the box. The isolation devices cannot be unlocked until every worker removes their lock from the box.

Option 3: Group Lock with Coordinator
A designated coordinator applies the primary lock. Each worker signs onto the group permit and places their lock on a group hasp. The coordinator is responsible for the overall procedure and is the last lock removed.

Regardless of method: no worker should ever be in a position where someone else can restore energy without their knowledge.

Electrical LOTO: Special Considerations

Electrical isolation gets its own section because it is the most common LOTO application and has unique hazards:

• Capacitors can hold a lethal charge long after power is disconnected. They must be discharged and grounded.
• Back-feed from generators, UPS systems, or interconnected circuits can energize equipment you thought was dead. Verify at the point of work, not just at the breaker.
• Induced voltage on de-energized conductors running parallel to energized ones. Test before touching.
• Battery systems cannot be locked out with a breaker. Disconnect terminals and isolate.
• Control circuits may be powered from a different source than the main power. Lock out all sources.

Always test with a rated voltage tester. Verify the tester works on a known live source before testing the de-energized circuit, and verify it still works after. This is called the Live-Dead-Live test.

Common LOTO Mistakes

1. Using tag out without lock out.
A tag is a communication device, not a physical barrier. Tags can be ignored, removed, or missed. A lock physically prevents energy restoration. Tags supplement locks - they do not replace them.

2. Forgetting stored energy.
You locked the breaker but did not bleed the hydraulic accumulator. You locked the valve but did not drain the line. Stored energy will release the moment you break a connection.

3. Not verifying zero energy.
"I locked it out, so it must be off." This assumption has killed people. Always verify. Every time. No exceptions.

4. Removing someone else's lock.
Only the person who placed the lock should remove it. If a worker leaves without removing their lock, use the company's lock removal procedure - which should require management authorization, verification that the worker is not on site, and a documented attempt to contact them.

5. Using LOTO devices for purposes other than LOTO.
Locks used for lockers, toolboxes, or other purposes should never be the same as LOTO locks. Dedicated LOTO locks should be standardized, identifiable, and used exclusively for energy isolation.

6. No equipment-specific procedures.
A generic "lock out the power" procedure does not address the five other energy sources on a hydraulic press. Every piece of equipment needs its own written LOTO procedure identifying every energy source and every isolation point.

OSHA LOTO Requirements (29 CFR 1910.147)

Key requirements under the standard:

• Written procedures for each piece of equipment (exceptions only for single-source, single-lockout equipment)
• Training for authorized employees (who perform LOTO), affected employees (who work near locked-out equipment), and other employees (who work in the area)
• Annual inspections of each LOTO procedure by an authorized employee other than the one using it
• Standardized locks and tags that are durable, identifiable, and used exclusively for LOTO
• Shift change procedures for transferring LOTO responsibility between shifts
• Contractor coordination when outside contractors work on or near locked-out equipment

Non-compliance penalties are significant. More significantly, non-compliance results in workers being exposed to uncontrolled energy that can kill them in an instant.

Building a LOTO Program That Works

The procedure is straightforward. Making it work in a real workplace requires:

Equipment-specific procedures: Walk every piece of equipment. Document every energy source. Identify every isolation point. Photograph them. Make the procedure available at the equipment location.

Proper hardware: Enough locks for every worker. Hasps for multi-lock situations. Lock boxes for group LOTO. Tags that are durable and standardized. Valve lockouts, breaker lockouts, and plug lockouts sized for your equipment.

Training that sticks: Hands-on practice, not just a slideshow. Workers should physically perform LOTO on actual equipment during training. Annual refresher with scenario-based exercises.

Enforcement: The procedure is worthless if supervisors allow shortcuts. Zero tolerance for bypassing LOTO - no exceptions for "quick jobs" or "just checking something."