LOTO lockout tagout is the safety procedure that prevents the unexpected release of hazardous energy while workers service or maintain equipment. For general contractors, understanding LOTO is not just about knowing the definition. It is about knowing how to enforce it across every subcontractor on your jobsite. OSHA reports that proper lockout/tagout procedures prevent an estimated 120 fatalities and 50,000 injuries every year in the United States.

This guide explains the full LOTO process, breaks down the worker categories, and shows GCs how to verify subcontractor compliance.

The LOTO Process: Step by Step

LOTO follows a specific sequence. Skipping steps is the primary cause of energy-release incidents. Here is the complete procedure.

Step 1: Prepare for shutdown. The authorized employee identifies the equipment, its energy sources, and the isolation points. They review the equipment-specific LOTO procedure and gather the necessary locks, tags, and devices.

Step 2: Notify affected employees. All workers who operate or work near the equipment must be notified that a lockout/tagout is about to begin. This notification includes who is performing the lockout, why, and the expected duration.

Step 3: Shut down the equipment. The authorized employee shuts down the equipment using normal operating procedures. This is the controlled shutdown, not an emergency stop.

Step 4: Isolate energy sources. The authorized employee operates the energy-isolating devices (circuit breakers, valves, disconnects) to isolate all hazardous energy from the equipment.

Step 5: Apply lockout/tagout devices. The authorized employee attaches their personal lock and tag to each energy-isolating device. Each worker servicing the equipment applies their own lock. No master keys.

Step 6: Release stored energy. Even after isolation, equipment may hold stored energy. Capacitors hold electrical charge. Hydraulic lines hold pressure. Springs hold mechanical energy. The authorized employee must release, restrain, or dissipate all stored energy.

Step 7: Verify zero energy state. Before starting work, the authorized employee attempts to restart the equipment using normal controls. The equipment should not operate. They also test for residual energy using appropriate instruments (voltage testers, pressure gauges).

Step 8: Perform service work. With zero energy confirmed, the service or maintenance work proceeds.

Step 9: Remove LOTO devices. After work is complete, the authorized employee inspects the equipment, removes tools and materials, reinstalls guards, and notifies affected employees. Only the worker who applied a lock may remove it.

Three Categories of Workers Under LOTO

OSHA defines three worker categories, each with different training requirements and responsibilities.

Worker Category	Definition	Training Required	Role in LOTO
Authorized employee	Locks out equipment to perform service	Full procedure training, equipment-specific training	Applies locks/tags, performs isolation, verifies zero energy
Affected employee	Operates equipment or works in the area	Awareness training about LOTO purpose and restrictions	Must not attempt to restart locked-out equipment
Other employee	Works near but not directly with the equipment	General awareness that LOTO exists and what tags mean	Must recognize and respect LOTO devices

On construction sites, electrical subcontractors, mechanical subs, and elevator contractors typically have authorized employees. Laborers, carpenters, and other trades working nearby are affected or other employees.

Equipment That Requires LOTO on Construction Sites

GCs must identify all equipment on their projects that falls under LOTO requirements. Common examples include:

Temporary electrical distribution panels and switchgear. HVAC systems during installation, testing, and commissioning. Elevator hoistways and machinery during installation. Pump stations and piping systems with pressurized lines. Generators and emergency power systems. Tower cranes during maintenance. Conveyor systems during installation.

Equipment that does not have stored energy and can be controlled by simply unplugging from a single source may qualify for an alternative to full LOTO procedures. However, most construction equipment has multiple energy sources and requires full LOTO.

How GCs Verify Subcontractor LOTO Compliance

Verification happens at two stages: prequalification and ongoing project monitoring.

During prequalification, collect these documents. Written LOTO procedures for equipment the sub will service on your project. Training records for all authorized employees showing initial and refresher training dates. Annual LOTO program inspection reports for the past two years. Lock and tag inventory showing standardized, employer-identified hardware.

During the project, monitor these activities. Observe LOTO procedures during site walks. Verify that locks are employer-specific and individually keyed. Confirm that tags include the authorized employee's name and date. Check that affected employees have received site-specific LOTO awareness training.

Document all verification activities. If an OSHA inspector asks about your LOTO oversight, you need records showing you monitored subcontractor compliance.

Group Lockout on Multi-Trade Projects

When multiple subcontractors service the same equipment, group lockout procedures add complexity. The GC must coordinate these situations.

A primary authorized employee takes overall responsibility for the group lockout. This person verifies that all energy sources are isolated and locked. Each individual worker then applies their own personal lock to a group lockout device (typically a hasp that accepts multiple locks).

Work cannot begin until every worker's lock is on the hasp. Equipment cannot be re-energized until every worker's lock is removed. The primary authorized employee removes their lock last.

GCs should designate the site superintendent or a safety manager as the coordinator for group lockout situations. This person does not need to be an authorized employee for the equipment, but they must understand the coordination process.

FAQs

What does LOTO lockout tagout mean? LOTO stands for Lockout/Tagout. It is the safety procedure for isolating hazardous energy sources before workers service or maintain equipment. Lockout uses physical locks on energy isolation devices. Tagout uses warning tags. The goal is to prevent the unexpected startup of equipment that could injure workers.

Who needs LOTO training on a construction site? Three groups need training. Authorized employees (who perform LOTO) need full procedural training. Affected employees (who operate or work near the equipment) need awareness training. Other employees (who work in areas where LOTO is used) need general recognition training. All subcontractors performing service work should have authorized employees.

How often must LOTO procedures be inspected? OSHA requires at least one annual inspection of the energy control program. The inspection must include a review of each employee's responsibilities under the LOTO procedure. An authorized employee other than the one being observed must conduct the inspection. Results must be documented and retained.

Can a tagout alone replace a lockout? Only when the energy-isolating device cannot physically accept a lock. OSHA strongly prefers lockout over tagout because locks provide physical restraint. When tagout alone is used, the employer must demonstrate that the tagout program provides protection equivalent to lockout through additional safety measures.

What happens if a worker needs to remove another worker's lock? OSHA requires that only the worker who applied a lock may remove it. If that worker is unavailable (left the site, emergency), the employer must follow a specific procedure: verify the worker is not on site, make every reasonable effort to contact them, and ensure they know the lock was removed before they return to work.

What is the GC's role in LOTO on a multi-employer site? The GC must coordinate LOTO activities between all subcontractors on the site. This includes verifying that each sub has written procedures, ensuring communication between employers during group lockout situations, and monitoring compliance during project execution. The GC can be cited for LOTO violations even if the sub performed the work.

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