What is Lockout Tagout? Energy Control

By R.W. Hurst, Editor

What is Lockout Tagout?

Lockout Tagout (LOTO) is a safety procedure used in industrial and maintenance settings to ensure that machines are properly shut off and not able to be started up again before maintenance or repair work is completed.

Lockout Tagout (LOTO) is a critical safety procedure that protects workers from hazardous energy during equipment maintenance or servicing. Mandated by OSHA in the United States (29 CFR 1910.147) and CSA Z460 in Canada, LOTO ensures that machinery is properly shut down, isolated from energy sources, and secured against accidental startup. By following a standardized lockout and tagout process, companies can prevent serious injuries, reduce liability, and maintain regulatory compliance.

According to OSHA Standard 1910.147, it is essential to distinguish between authorized employees and affected employees when implementing hazardous energy control procedures. Authorized employees are those who perform the maintenance or servicing tasks and are responsible for applying LOTO devices to control hazardous energy. In contrast, affected employees operate the machines or equipment being serviced or work in areas where such servicing is performed. Before any maintenance begins, a lockout device must be properly applied to ensure that machinery and equipment remain in a de-energized state. This process involves isolating energy sources and securing them with approved lockout tagout devices, such as padlocks, hasps, and tags, to prevent accidental startup or release of stored energy. Proper training and clear role definitions are critical to ensure the safety of everyone involved in the operation or servicing of machines or equipment.

Why Lockout Tagout Is Important

In industrial environments, equipment often contains multiple energy sources—electrical, mechanical, hydraulic, pneumatic, or thermal. Without proper control, these sources can cause serious injuries or fatalities. Lockout Tagout procedures are legally mandated by regulatory authorities such as OSHA in the United States (29 CFR 1910.147) and CSA Z460 in Canada. These standards define employer responsibilities for protecting workers during maintenance activities.

Beyond compliance, LOTO is a cornerstone of workplace safety culture. It promotes accountability, communication, and a proactive approach to risk management. A well-executed LOTO program not only saves lives but also reduces equipment damage and operational downtime.

Core Elements of the LOTO Process

While procedures may vary based on equipment and energy types, the basic structure of a Lockout Tagout process includes:

Preparation – Identify the equipment to be serviced, its energy sources, and the required isolation methods.
Shutdown – Turn off the equipment using its normal operating controls.
Isolation – Physically disconnect or block each energy source, such as turning off breakers or closing valves.
Lockout – Apply locks to secure energy-isolating devices in the off position.
Tagout – Attach a tag to each lock indicating who applied it and why.
Verification – Confirm that the machine is fully de-energized before work begins.
Restart – After work is completed and all personnel are clear, remove locks and tags in coordination with authorized workers.

Each step must be followed carefully, and any variation can increase the risk of harm.

Lockout vs. Tagout

The term "Lockout Tagout" combines two distinct but related safety practices:

Lockout uses physical devices—like padlocks—to keep isolation points secured. This is the preferred method because it provides a physical barrier to re-energization.
Tagout involves placing a clearly visible warning tag on the energy isolation device. While it alerts others not to operate the equipment, it doesn’t provide the same level of protection as a lock. OSHA permits tagout only when lockout isn’t feasible.

In most situations, using both lockout and tagout in tandem is best practice.

Types of Hazardous Energy Controlled by LOTO

LOTO procedures are designed to manage a wide range of energy sources, such as:

Electrical energy (live wires, panels, circuits)
Mechanical energy (moving parts, spring-loaded components)
Hydraulic and pneumatic energy (pressurized systems)
Thermal energy (hot surfaces, steam systems)
Chemical energy (reactive substances under pressure)

Each source requires specific isolation devices and safety precautions. Failure to isolate all relevant forms of energy can result in unexpected movement or exposure.

Who Needs to Use Lockout Tagout?

LOTO procedures must be followed by any worker who services, repairs, cleans, or inspects machinery where accidental startup could pose a hazard. This includes electricians, millwrights, maintenance technicians, and contractors. Supervisors and safety managers are responsible for ensuring that LOTO policies are enforced and that personnel are trained and certified.

Building a Culture of Energy Control

Successful Lockout Tagout programs go beyond procedures—they require employee training, routine audits, and clearly documented responsibilities. Every employee should understand their role in preventing hazardous energy exposure, whether they're performing the lockout or simply working in proximity to locked-out equipment.

A strong LOTO program communicates that worker safety is a non-negotiable priority. Lockout Tagout isn’t just about compliance—it’s about creating safer workspaces, one machine at a time.

Frequently Asked Questions (FAQ)

What is the main purpose of Lockout Tagout?

Lockout Tagout is designed to protect workers by ensuring that hazardous energy is completely isolated and controlled during maintenance or servicing of equipment.

Who is required to follow LOTO procedures?

Any employee who services, maintains, or works near equipment that could start unexpectedly must follow LOTO procedures. This includes electricians, mechanics, and technicians.