Every year, workers are severely injured or killed because a machine was inadvertently turned on, or because stored energy (like a compressed spring or trapped hydraulic pressure) was unexpectedly released. A compliant LOTO program eliminates this risk through strict, step-by-step isolation.
Understanding Hazardous Energy Types
Most people associate LOTO strictly with electricity, but hazardous energy comes in many forms. Before a machine can be considered safe, a worker must identify and isolate all potential energy sources.
- Electrical: Main power feeds, capacitors, and backup generators.
- Mechanical (Kinetic & Potential): Moving parts, gravity (elevated loads that could fall), and tension (compressed springs).
- Pneumatic & Hydraulic: Pressurized air lines and pressurized fluid running to cylinders.
- Thermal & Chemical: Steam valves, hot fluids, or hazardous chemical lines feeding into the equipment.
The 6 Essential Steps of LOTO
A legally compliant Lockout/Tagout procedure is not just throwing a padlock on a breaker. It requires a documented process:
- Preparation: Identify all energy sources tied to the equipment.
- Shutdown: Power down the machine using normal operating controls.
- Isolation: Physically disconnect or block the energy sources (e.g., throwing the main disconnect switch, closing valves).
- Lock and Tag: Apply authorized padlocks and warning tags to the isolation devices. Every worker involved must apply their *own* lock.
- Bleed Stored Energy: Release any trapped pressure, block elevated parts, and discharge capacitors.
- Verify (The Zero Energy State): Attempt to start the machine using the normal controls to prove that the isolation was completely successful.
LOTO and Power Press Maintenance
Machine guarding (like light curtains) protects operators during normal production. However, if a die needs to be swapped or a jam cleared on a mechanical power press, those guards must be bypassed. This is where strict LOTO rules take over. You must achieve a Zero Energy State before reaching into the point of operation.
Read our full guide on Power Press & Machine Guarding Compliance →Frequently Asked Questions
Who is allowed to remove a LOTO padlock?
Legally, only the person who applied the lock is allowed to remove it. If that worker leaves the site and forgets to remove their lock, there is a strict, documented emergency removal procedure that usually involves contacting the worker and having the plant manager cut the lock.
Can I share my LOTO key with a coworker?
Absolutely not. A LOTO padlock must have only one key, and that key must stay in the pocket of the worker who applied the lock. Sharing keys completely compromises the integrity of the safety system.
What is a group lockout?
When a large maintenance team works on a complex machine, a primary supervisor may lock out all energy sources and place the keys inside a "group lockbox." Every individual worker then places their own personal padlock on the outside of that box. The machine cannot be re-energized until every single worker removes their personal lock.
What is the difference between an Authorized and Affected employee?
An Authorized Employee is the person actively performing the maintenance who applies the locks. An Affected Employee is the person who normally operates the machine. Affected employees must be notified of the lockout, but they do not apply locks themselves.
Can a tag be used without a lock?
In very rare cases where a machine physically cannot accept a padlock, a Tagout-only system can be used. However, OSHA and Ministries of Labour require the employer to prove that the Tagout system provides the exact same level of protection as a physical lock, which is extremely difficult to do.
What makes a LOTO padlock different from a standard padlock?
LOTO locks must be standardized by color or shape within a facility, they must explicitly identify the worker who applied them (often with a photo or engraved name), and they must not be used for any other purpose (like locking a toolbox).
Is cord-and-plug equipment exempt from LOTO?
Usually, yes. If a machine (like a bench grinder or drill press) is powered by a single electrical plug, it does not require a formal lockout procedure provided the plug is completely unplugged and remains under the exclusive, continuous control of the person performing the maintenance.
How often must an employer review their LOTO procedures?
OSHA and Canadian safety standards require employers to conduct a periodic inspection of their energy control procedures at least annually. This audit ensures the procedures are accurate and employees are following them correctly.