The OSHA-Required LOTO Sequence

OSHA 1910.147(d) prescribes a specific six-step sequence for controlling hazardous energy. These steps must be followed in order every time lockout/tagout is performed. Skipping or reordering steps creates gaps that can result in serious injury or death.

Step 1: Preparation

Before touching any equipment, the authorized employee must understand what they are about to lock out. This means identifying:

  • The type and magnitude of energy the machine uses or stores
  • The hazards associated with that energy
  • The specific method and means for controlling each energy source

This is not a formality. An authorized employee who does not understand the energy sources they are isolating cannot perform lockout safely. The written procedure for the specific equipment should provide all of this information.

Step 2: Shutdown

Shut down the machine using the established operating procedure. The standard requires an "orderly shutdown" to avoid creating additional hazards. For example, a machine with a rotating blade must be allowed to coast to a stop rather than forcing an emergency stop that could cause the blade to seize or fragment.

Notify all affected employees that the equipment is being shut down for servicing before you begin.

Step 3: Isolation

Locate and operate all energy isolating devices to disconnect the equipment from every energy source. This means opening breakers, closing valves, inserting blocks, or operating disconnect switches.

Every energy source identified in the preparation step must have a corresponding isolation action. If the procedure calls for isolating three energy sources, three isolation devices must be operated.

Step 4: Lock/Tag Application

Affix a lockout device (lock) or tagout device (tag) to each energy isolating device. Each device must:

  • Hold the isolating device in the safe/off position (locks) or clearly indicate that operation is prohibited (tags)
  • Identify the authorized employee who applied it
  • Be applied by the authorized employee performing the work, not by someone else on their behalf

If a tag is used on a device that can be locked out, the tag must be attached at the same location where a lock would be placed.

Step 5: Stored Energy Release

Even after isolation, stored or residual energy may remain in the system. All stored energy must be relieved, disconnected, restrained, or otherwise rendered safe:

  • Discharge capacitors
  • Release or block springs
  • Lower or block elevated components
  • Bleed hydraulic and pneumatic lines to zero pressure
  • Drain and vent steam lines
  • Allow heated surfaces to cool or provide barriers

If energy can reaccumulate (some thermal and chemical systems), verification must continue throughout the servicing work until the possibility no longer exists.

Step 6: Verification

This is the step that confirms everything else worked. The authorized employee must verify isolation and deenergization by attempting to start the equipment using its normal operating controls.

The equipment should not respond. If it does, something was missed. Stop, investigate, and repeat the isolation process.

After verification, return all operating controls to the neutral or off position so that the equipment does not start unexpectedly when locks are eventually removed.

After Servicing: The Release Sequence

When work is complete, the release sequence under 1910.147(e) requires: inspecting the work area, verifying all employees are clear, notifying affected employees, and removing each lock/tag (each worker removes their own). Only then can the equipment be reenergized.

Making It Practical

These six steps are only as effective as the written procedure that supports them. A clear, equipment-specific procedure with precise isolation point locations and step-by-step instructions makes the difference between a crew that follows LOTO correctly and one that takes shortcuts. Learn how to write effective LOTO procedures.