Lockout Tagout (LOTO): How Hazardous Energy Control Works on Industrial Maintenance Sites

A motor that looks switched off isn’t always off. A conveyor can hold tension in its belt long after the power is cut. A hydraulic line can stay under pressure for hours. Someone in another part of the plant can flip a breaker without knowing a crew is inside the machine. Lockout tagout exists because of moments like these. It’s the simple, strict routine that makes sure equipment stays dead while people are working on it.

If you run a plant, manage maintenance, or hire contractors for shutdown work, this is one of the few safety procedures where a small shortcut can cost someone their life. Here’s how lockout tagout actually works, where it gets messy on a real industrial site, and what good looks like.

What Is Lockout Tagout?

Lockout tagout, often shortened to LOTO, is a method of controlling hazardous energy while equipment is being serviced or repaired. Two things happen together. First, the energy source is isolated and physically locked in the “off” position. Second, a tag goes on the lock to say who applied it, why, and that the equipment must not be operated.

The lock and the tag do different jobs. The lock is a physical barrier. It stops someone from turning the equipment back on, even by accident. The tag is a message. It tells everyone else on site that a person is working on this machine right now. Canada’s national standard, CSA Z460, covers this whole topic under the title “Control of Hazardous Energy – Lockout and Other Methods.” The Canadian Centre for Occupational Health and Safety has a clear overview of lockout and tag out if you want to see how the standard defines the terms.

The Types of Energy Lockout Tagout Has to Control

Most people think of electricity first. That’s only part of the picture. A proper lockout tagout procedure has to deal with every energy source that could hurt someone:

Electrical: motors, panels, and control circuits
Hydraulic and pneumatic: pressurized lines that can move a cylinder without warning
Mechanical: spinning shafts, flywheels, and belts that keep moving after power is cut
Gravity: raised loads, hoppers, and anything that can drop or slide
Stored energy: springs, capacitors, and pressurized vessels
Thermal and chemical: hot surfaces, steam, and process material in the lines

A crew that only locks out the electrical disconnect has handled one hazard out of several. The others are still there, waiting.

Lockout Tagout Step by Step

The exact procedure is written for each machine, but the order stays the same on almost every job.

Plan the job. Find every energy source the machine has. Check the equipment drawings, not just the panel in front of you.
Tell everyone affected. Operators and nearby crews need to know the machine is coming down.
Shut the equipment down the normal way, so nothing stops in an unsafe state.
Isolate every energy source. Open the disconnects, close the valves, and block anything that could move.
Apply locks and tags. Each person working on the equipment puts on their own lock.
Release or restrain stored energy. Bleed the pressure, drain the line, and support raised loads.
Verify. Try to start the machine. If it starts, the lockout has failed. If nothing happens, return the controls to “off” and go to work.
Restore the equipment. Remove tools, clear the area, and take off locks only when the job is finished, and only by the person who put each one on.

Step seven is the one people skip when they’re in a hurry. It’s also the step that catches the mistakes from steps one through six.

Lockout Tagout on a Multi-Trade Shutdown

This is where a textbook procedure meets a real site. During a shutdown, a single piece of equipment might have millwrights, welders, scaffolders, and electricians all working on or around it. Locking it out for one person isn’t enough. Everyone with hands in the machine needs the same protection.

That’s what group lockout is for. The equipment is isolated once. The keys to those locks go into a lock box. Then each worker adds their own personal lock to the box. The machine can’t be re-energized until every single person has removed their lock. If one person is still inside, the box stays locked.

A few things keep this working on a busy site:

One person owns the master lock plan. Someone is clearly in charge of isolation for each piece of equipment.
Shift change has a handover. Locks from the outgoing crew don’t come off until the incoming crew has their own on.
Locks are personal. Nobody removes another person’s lock, ever. If someone leaves site with a lock still on, there’s a defined process to deal with it, and it doesn’t involve bolt cutters and a guess.
Trades talk to each other. A millwright doing an alignment and a welder repairing a guard on the same machine need to know about each other before either one starts.

This is the same kind of coordination that runs a plant turnaround, where dozens of jobs share tight schedules and shared equipment. Lockout tagout is one of the systems that keeps all of that from colliding.

Common Lockout Tagout Mistakes

Most lockout failures aren’t dramatic. They’re small habits that pile up:

Skipping the verification step because “I already turned it off.”
Locking out the wrong disconnect on a machine with more than one power source.
Forgetting stored energy, especially pressure in hydraulic lines or a raised load.
Using tags alone where a lock is required. A tag is a warning. It isn’t a barrier.
Sharing a lock or a key between workers to save time.
Letting the written procedure go stale after equipment has been modified.

That last one matters more than it sounds. If a machine has been changed since the procedure was written, the procedure may no longer list every energy source. Up-to-date drawings matter here, which is one reason accurate as-built drawings are worth keeping current.

How Lockout Tagout Fits Into Your Safety Program

Lockout tagout doesn’t stand alone. It works best as part of a system where crews talk about it every day, not just when someone reads the binder.

Daily toolbox talks are a natural place to confirm which equipment is locked out, who owns each lock, and what’s changed since yesterday. And on sites where COR certification matters, a documented and practiced hazardous energy control program is the kind of evidence auditors want to see. It shows the safety system works on the floor, not just on paper.

It also connects to the maintenance work itself. Whether a crew is doing repair and maintenance on a gearbox, checking a drive with vibration analysis, or scanning a motor control centre with thermal imaging, the equipment has to be in a known, safe state first. Some of that inspection work happens on running equipment under strict rules. The rest happens only after lockout is verified.

What to Ask a Contractor About Lockout Tagout

If you’re hiring a contractor for maintenance or shutdown work, a few questions show quickly how seriously they take this:

Do you have a written lockout procedure for each type of equipment, or a generic one for everything?
How do you run group lockout when several trades share the same machine?
Do your workers each apply their own personal lock?
How do you handle shift change while equipment is locked out?
Who verifies isolation before work starts?

Clear, specific answers usually mean the procedure is used every day. Vague answers usually mean it’s a document sitting in a folder.

Frequently Asked Questions About Lockout Tagout

What does lockout tagout mean?

Lockout tagout is a safety procedure that isolates hazardous energy from a machine and locks it off, with a tag showing who applied the lock. It protects workers from unexpected startup or the release of stored energy during maintenance and repair.

What’s the difference between lockout and tagout?

Lockout uses a physical lock to keep an energy-isolating device in the safe position. Tagout is the warning label attached to it. Tags are used together with locks, not as a replacement for them.

Who can remove a lockout lock?

Only the person who applied the lock. This is what makes the system reliable. Every worker controls their own protection, and the equipment stays off until the last lock is gone.

What is group lockout?

Group lockout is used when several workers or trades service the same equipment. The equipment is isolated once, the keys go into a lock box, and each worker places a personal lock on the box. Nothing can be re-energized until every lock is removed.

Does lockout tagout apply to stored energy?

Yes. Stored energy such as pressure, springs, and raised loads must be released or restrained before work starts. Isolating the power source alone isn’t enough.

Zero Energy Before Any Work Starts

Lockout tagout comes down to one rule that never bends: nobody works on equipment until it’s proven safe, and nobody removes protection that belongs to someone else. On a busy shutdown, that discipline is what lets crews work close together without anyone getting hurt.

At Credence Construction, hazardous energy control is part of how our crews approach maintenance and shutdown work across mining, agricultural, and industrial sites in Saskatchewan, Alberta, Manitoba, and Western Ontario. If you want a maintenance partner who takes isolation seriously before the first wrench turns, call us at 306-786-7000.