3.3 Lockout/Tagout (LOTO) in Construction

Lockout/Tagout (LOTO) in Construction

Servicing and maintaining machinery or electrical circuits exposes construction workers to severe hazards from the unexpected release of hazardous energy. This energy can take many forms, including electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and gravity. To prevent serious injuries and fatalities, employers must implement rigorous isolation and control procedures. While the construction industry has a specific standard for locking and tagging circuits under 29 CFR 1926.417, OSHA also applies the comprehensive Lockout/Tagout (LOTO) standard from General Industry (29 CFR 1910.147) to ensure complete worker safety during servicing and maintenance activities.

---

Construction Tagging Rules vs. General Industry LOTO

The construction electrical standard under Subpart K features a relatively brief rule regarding de-energized circuits:

• 29 CFR 1926.417(a) Controls: Controls that are to be deactivated during the course of work on equipment or circuits must be tagged.
• 29 CFR 1926.417(b) Equipment and Circuits: Equipment or circuits that are de-energized must be rendered inoperative and must have tags attached at all points where such equipment or circuits can be energized.
• 29 CFR 1926.417(c) Tags: Tags must plainly identify the equipment or circuits being worked on.

The Enforcement Gap

Historically, the construction standard relied heavily on tags. However, tags are only warning devices; they do not physically prevent someone from flipping a switch or energizing a line. Because of this, OSHA enforces a full Lockout/Tagout program incorporating physical locks under 29 CFR 1910.147 for any construction activity involving the servicing and maintenance of machinery where unexpected energization could cause injury.

Standard industry practice—and OSHA compliance guidelines—require the use of both physical locks and tags. If a circuit or machine cannot accept a lock, a tagout system may be used alone only if the employer can demonstrate that the tagout program provides a level of safety equivalent to a lockout program.

---

Key LOTO Roles and Devices

To implement a successful LOTO program, it is essential to understand the defined roles and terms:

• Energy Isolating Device: A mechanical device that physically prevents the transmission or release of energy. Examples include a manually operated electrical circuit breaker, a disconnect switch, a line valve, or a block. Note: Push buttons, selector switches, and other control-circuit devices are not energy isolating devices, as they do not physically isolate the power source and can be easily bypassed or fail.
• Authorized Employee: An employee who locks out or tags out machines or equipment in order to perform servicing or maintenance. They are the only individuals permitted to apply and remove LOTO devices.
• Affected Employee: An employee whose job requires them to operate or use a machine or equipment on which servicing or maintenance is being performed under lockout or tagout, or whose job requires them to work in an area in which such servicing or maintenance is being performed. Affected employees must be notified before LOTO is applied and after it is removed, and they are never allowed to perform work on the isolated machine.

---

The 6-Step Lockout/Tagout Procedure

To safely de-energize and isolate a machine or electrical circuit, the authorized employee must execute the following six steps in precise sequence:

1. Preparation for Shutdown

The authorized employee must identify all energy sources feeding the equipment, understand the hazards, know the magnitude of the energy, and identify the correct methods to control it.

2. Machine or Equipment Shutdown

The machine must be turned off using its normal operating controls (e.g., stop buttons, control panel switches).

3. Machine or Equipment Isolation

All energy isolating devices must be physically operated to isolate the machine from its energy sources. This includes pulling electrical disconnect switches, turning off circuit breakers, and closing block valves.

4. Application of Lockout/Tagout Devices

The authorized employee must attach their personal lock and tag to each energy isolating device. The lock must hold the device in a safe, "off" position. The tag must state the worker's name, date, company, and a clear warning (e.g., "Do Not Operate").

5. Dissipation of Stored Energy

All residual or stored energy must be safely released, discharged, blocked, or otherwise rendered safe. This includes:

• Discharging electrical capacitors.
• Bleeding air pressure from pneumatic lines.
• Draining hydraulic fluid lines.
• Releasing spring tension.
• Placing physical blocks under elevated components that could fall due to gravity.

6. Verification of Isolation (The "Try" Step)

This is the most critical safety step. The authorized employee must verify that the machine is completely de-energized.

• First, ensure that no other workers are exposed to hazards.
• Attempt to start the machine using the normal operating controls.
• Test electrical circuits with a calibrated, functioning voltmeter.
• Crucial: Return all operating controls to the "off" or neutral position after verification so the machine does not unexpectedly restart when LOTO is removed.

---

Lockout/Tagout Device Removal

The general rule is that each lockout or tagout device must be removed from the energy isolating device by the authorized employee who applied it. This prevents the possibility of a supervisor or coworker re-energizing a machine while another worker is still inside or in contact with live components.

Emergency Lock Removal Protocol

If an authorized employee is not present at the facility (e.g., they went home with the key in their pocket), the employer may remove the lock ONLY if a strict, written emergency removal protocol is followed:

1. Verification: Confirm that the authorized employee is not at the facility or jobsite.
2. Contact: Make all reasonable efforts to contact the employee to inform them that their lock is being removed.
3. Notification: Ensure that the authorized employee has this knowledge before they return to work at the facility. The supervisor must physically meet the worker upon arrival to inform them that their lock was removed.

---

Group Lockout/Tagout (29 CFR 1910.147(f)(3))

When multiple employees, crews, or subcontractors are performing servicing or maintenance on the same equipment, group LOTO procedures must be utilized.

• Individual Control: Every authorized employee must maintain individual control over their safety. This means each worker must attach their own personal lock and tag to a group lockout device (such as a multi-lock hasp or a lockbox) before they begin work, and remove it only when they complete their portion of the work.
• No Delegation: A supervisor or foreman is never permitted to lock out equipment on behalf of a group of workers (a prohibited practice known as "one lock for the crew"). If a supervisor applies a single lock, they could remove it while another crew member is still working.
• Group Lockbox System: In a lockbox system, the main equipment isolation locks are locked, and their keys are placed inside a secure box. Each authorized employee then attaches their personal lock to the box. The keys cannot be accessed to open the main equipment locks until every single worker has finished their work and removed their personal lock from the box.