How to Use a Lockout Hasp: OSHA Steps, Shift Changes, and Removal

To use a lockout hasp, shut the equipment down through its normal stopping procedure, clamp the hasp’s jaws around the correct energy isolating device (a breaker, disconnect, or line valve), and have every authorized worker on the job thread a personal padlock and identification tag through one of the hasp’s holes. Release any stored energy, verify isolation by attempting to start the machine or by testing with a meter, and only then begin work. When the job is done, each worker removes their own lock; the hasp comes off after the last lock is gone.

What the Hasp Actually Does

A lockout hasp has a scissor-style pair of jaws that clamp around an energy isolation point. The overlapping handles carry a row of holes that align when the handles are squeezed together, and each hole accepts one padlock. Because the hasp cannot open until every padlock is removed, no single worker can restore power while anyone else’s lock is still attached. That mechanism is what makes group lockout work under 29 CFR 1910.147, which requires each authorized employee to affix their own personal lockout device to a group lockout device before starting work.¹

Choose the Right Hasp Before You Start

A hasp only works if it physically fits the isolation point and suits the environment around it. Using the wrong type can introduce a hazard rather than remove one. A conductive metal hasp placed near energized electrical components, for example, creates the sort of danger the lockout was meant to prevent.

Steel scissor-action hasps are the standard choice for typical valves, switches, and breakers. Vinyl coatings improve grip and resist corrosive chemicals.
Aluminum hasps are lighter and non-sparking, used where steel could create a spark hazard near flammable materials.
Dielectric nylon hasps are fully non-conductive and are required near high-voltage circuits where a metal hasp could conduct current or trigger an arc flash.
Flexible cable hasps use a plastic-coated steel cable to loop through oddly shaped isolation points that rigid jaws won’t fit.
Spark-resistant bronze hasps are for explosive atmospheres where even aluminum could pose an ignition risk.

Confirm the jaw diameter fits snugly. A loose hasp can leave enough play for someone to operate the energy control device even with the hasp attached.

Attach the Hasp to the Right Device

The hasp goes on an energy isolating device, meaning a mechanical device that physically prevents energy transmission: a circuit breaker, disconnect switch, or line valve. Push buttons, selector switches, and other control-circuit devices do not qualify.¹ Locking out a start/stop button accomplishes nothing if the circuit can be energized from another control point. The hasp goes on the breaker or disconnect, not the operating switch.

One scope note worth knowing: the standard does not cover cord-and-plug equipment when the worker unplugs it and keeps the plug under their exclusive control.² For everything else, a hasp on the isolation point is the point of the exercise.

Step by Step: Applying and Removing the Hasp

Prepare

Pull the written energy control procedure for the specific machine you’re working on. It should identify every energy source, every isolation point, and the sequence for shutting things down. Working from memory is one of the fastest ways to miss a secondary energy source. Count the workers who will be locking on. If more people need to attach locks than the hasp has holes, add a second hasp or use a group lockbox. Gather individual keyed padlocks and weather-resistant tags that identify each worker by name.¹

Shut Down and Apply

Use the normal stopping procedure to shut the equipment down. Move to the energy isolation point and place the hasp jaws around the breaker, disconnect, or valve. Squeeze the handles until the padlock holes align. Each authorized worker threads their own padlock through one hole and locks it, then attaches an identification tag. Every tag must display a warning such as “Do Not Start” or “Do Not Operate” and identify the employee who applied it. Tags must remain legible through weather, moisture, and corrosive environments, and the attachment must be non-reusable, self-locking, and require at least 50 pounds of force to remove.³

Release Stored Energy

Locking the isolation point is not the end of the job. Capacitors may hold electrical charge, hydraulic lines retain pressure, and springs can release mechanical force even after the main power is cut. The written procedure should specify how to bleed, block, or otherwise dissipate that residual energy before work begins.

Verify Isolation

Before touching the equipment, verify that isolation is complete. The most direct method is attempting to start the machine using its normal operating controls; with energy isolated, nothing should happen. For electrical circuits, a voltmeter confirms zero energy. Complex systems may need a combination of methods depending on how many types of energy are present.⁴ Return every operating control to off or neutral after the tryout, so no one mistakes a failed start attempt for normal operation.

Remove

When the work is finished and the area is cleared, each worker removes their own padlock. The rule is strict: the person who applied the lock is the person who removes it.¹ Once the final padlock is off, detach the hasp from the isolation point and re-energize the equipment following the written procedure.

Shift Changes and Abandoned Locks

Jobs that span multiple shifts create a gap where protection could lapse if locks are pulled and reapplied haphazardly. The standard requires an orderly transfer of lockout protection between outgoing and incoming workers, so the equipment is never unprotected during the handoff.³ In practice, the incoming crew applies their locks before the outgoing crew removes theirs.

If a worker leaves the site without removing their lock, the employer may remove it, but only under a documented procedure with three steps: verify that the employee is not at the facility, make all reasonable efforts to contact them to inform them the lock has been removed, and ensure they know about the removal before resuming work at the facility.¹ Cutting a lock without following those steps is a violation, not a shortcut.

What the Hasp Itself Has to Be

OSHA sets three performance requirements every lockout device, including a hasp, must meet under 29 CFR 1910.147(c)(5):¹

Durable enough to withstand the environment where it’s used for as long as the exposure lasts.
Standardized within the facility by at least one of color, shape, or size, so workers recognize a lockout device instantly.
Substantial enough to resist removal without extreme force or cutting tools such as bolt cutters.

The employer supplies the hardware. The standard requires locks, tags, chains, hasps, and other necessary equipment to be provided by the employer for isolating and securing machines from energy sources. Each device must be used solely for energy control and cannot double as a general-purpose lock elsewhere in the facility.¹ If a worker is being asked to bring their own padlock from home for a lockout, something is off.

1
eCFR. 29 CFR 1910.147 – The Control of Hazardous Energy (Lockout/Tagout)
2
Occupational Safety and Health Administration. Numerous Questions on Lockout/Tagout Under 1910.147 and Subpart S
3
Occupational Safety and Health Administration. 29 CFR 1910.147 – The Control of Hazardous Energy (Lockout/Tagout)
4
Occupational Safety and Health Administration. Lockout/Tagout eTool – Energy Control Program