Level 1, Unit 1, Section 1 – 1.7 Lock Out and Tag Out (LOTO)

1.7.1 — Types of Hazardous Energy

Hazardous energy can take many forms in refrigeration and air conditioning systems. Workers must be able to identify all forms present in their workplace before beginning any lockout.

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Electrical

Motors and compressors
Lighting and control circuits
Capacitors (store energy even when disconnected)
Batteries and UPS systems

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Mechanical

Rotating equipment (fans, compressors, motors)
Conveyor belts
Flywheels and rotating masses
Springs under tension

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Pneumatic

Compressed air in systems and equipment
Control valves operated by compressed air

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Hydraulic

Hydraulic lifts and positioning equipment
Hydraulic accumulators

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Thermal

Hot or cold fluids in pipes and vessels
Hot surfaces that could cause burns
Steam systems

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Pressure

Refrigerant in systems
Compressed gas cylinders
Pressurized vessels and tanks

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Chemical

Refrigerants, oils, and other fluids that could be released
Cleaning chemicals and process fluids

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Gravitational

Suspended loads or equipment
Equipment or materials at height
Counterweights and balances

1.7.2 — When Is Lockout Required?

Lockout is required whenever workers could be exposed to hazardous energy. The following activities always require full LOTO procedures:

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Activities Requiring Lockout

Mandatory

Servicing or maintenance of equipment
Clearing jams or blockages
Cleaning equipment
Repairing or adjusting equipment
Any activity where guards or protective devices are removed or bypassed

1.7.3 — Lockout / Tagout Procedures

The LOTO procedure follows a strict sequence of 13 steps organized into eight phases. Every step must be completed in order — never skip or shortcut any phase.

Phase 1 Preparation

1

Identify Energy Sources

Review equipment documentation and drawings
Identify all energy sources (electrical, mechanical, pneumatic, hydraulic, thermal, chemical, gravitational)
Identify all isolation points (disconnects, valves, breakers)
Consider stored energy (capacitors, springs, elevated components)

2

Develop Lockout Procedure

Document step-by-step procedure for isolating equipment
Specify isolation devices and lockout points
Identify required PPE and tools
Establish verification methods to confirm zero energy state

3

Notify Affected Workers

Inform operators and other affected personnel that equipment will be shut down and locked out
Explain the nature of work to be performed and expected duration

Phase 2 Shutdown

4

Orderly Shutdown

Use normal shutdown procedures to stop equipment
Ensure all functions have ceased
Never rely on control switches alone

Phase 3 Isolation

5

Isolate Energy Sources

Electrical: Open disconnects, circuit breakers, or remove fuses
Mechanical: Disengage drives, block movement, release springs
Fluids: Close valves, install blanks, drain or bleed systems
Pneumatic/Hydraulic: Close supply valves, bleed pressure, block movement
Gravitational: Lower suspended loads, install blocks or supports

Phase 4 Lockout / Tagout Application

6

Apply Locks and Tags

Apply personal lock to each isolation device
Each worker applies their own lock (group lockout procedures for multiple workers)
Use locks that can only be removed by the person who installed them
Attach tag indicating: name, date/time, reason for lockout, contact information
If locking is not possible, use tagout with additional safety measures — tags alone are warning devices, not physical barriers

Phase 5 Control of Stored Energy

7

Release or Restrain Stored Energy

Discharge capacitors using appropriate grounding procedures
Release tension from springs
Block or support elevated components
Vent or bleed pressure from lines and vessels
Allow hot components to cool (or implement thermal protection)

Phase 6 Verification

8

Verify Zero Energy State

Attempt to start equipment using normal controls (verify controls are disabled)
Test voltage tester on known live source → test locked-out circuit → test tester on live source again
Verify mechanical components cannot move
Verify pressure gauges read zero
Document verification

Phase 7 Perform Work

9

Safely Perform Maintenance or Service

Proceed with work only after verification of zero energy
Re-verify if work extends over multiple shifts or breaks
Maintain lockout throughout the work

Phase 8 Return to Service

10

Prepare for Re-energization

Ensure all tools and equipment are removed
Reinstall guards and safety devices
Verify equipment is ready for operation

11

Remove Lockout Devices

Ensure all personnel are clear of equipment
Each worker removes their own lock and tag
Never remove another person's lock

12

Notify Affected Workers

Inform operators and affected personnel that lockout is being removed and equipment will be re-energized

13

Re-energize Equipment

Restore energy sources in the appropriate sequence
Test equipment operation
Return to normal operation

1.7.4 — Lockout Devices and Equipment

Proper lockout relies on standardized hardware. Knowing what device to use for each energy source is a core competency.

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Locks

Keyed differently so each worker has a unique key. Standardized red color. Used only for lockout purposes — never as general padlocks.

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Tags

Provide warning ("Danger — Do Not Operate") and identification. Attached securely and include worker name, contact info, date, and reason.

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Hasps

Allow multiple workers to apply individual locks to a single isolation point. Each lock must be removed before the hasp opens.

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Valve Lockouts

Devices that fit over valve handles to prevent operation. Available for ball valves, gate valves, and butterfly valves.

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Circuit Breaker Lockouts

Clamp over breaker handles to prevent the breaker from being switched on during work.

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Plug Lockouts

Cover electrical plugs to prevent accidental reconnection to power.

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Blank-Off Plates (Flange Blinds)

Inserted into flanged piping to positively block the flow of fluids or gases. Cannot be bypassed by simply opening a valve.

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Chains and Cables

Secure larger equipment or multiple isolation points simultaneously.

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Blocks and Chocks

Prevent movement of mechanical components such as rotating shafts, elevated platforms, or heavy doors.

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Caps and Plugs

Seal open lines or ports to prevent release of fluids, gases, or inadvertent connection.

1.7.5 — Group Lockout

When multiple workers are involved in a job, group lockout procedures ensure each worker is independently protected throughout the task.

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How Group Lockout Works

Each worker applies their personal lock to a group lockout box or hasp. The box controls access to the keys for isolation devices. Equipment cannot be re-energized until every worker has removed their personal lock. A supervisor or qualified person coordinates the overall lockout and verifies all workers are accounted for.

1.7.6 — Special Lockout Situations

Certain circumstances require modified or additional procedures to maintain worker protection.

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Shift Changes

Outgoing worker verifies equipment status with incoming worker
Incoming worker applies their lock before outgoing worker removes theirs
Continuity of protection must be maintained at all times

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Temporary Re-energization for Testing

May be necessary to verify that repairs are functioning correctly. Follow this specific sequence:

Remove all tools and materials from the work area
Reinstall all guards and safety devices
Ensure all workers are clear of the equipment
Remove lockout devices temporarily and re-energize for testing
De-energize and re-apply full lockout before resuming work

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Lost or Forgotten Lock Removal

If a lock must be removed in the absence of the person who applied it:

Make every effort to contact the person first
Verify that the person is not working on the equipment
Follow the facility procedure — typically requires supervisor authorization
Inspect equipment thoroughly before removing the lock
Notify the person that their lock was removed before they return to work

1.7.7 — Verification and Testing Equipment

Correct test equipment must be used to confirm the absence of hazardous energy before work proceeds.

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Solenoid-Type Voltage Testers

Provide both audible and visible indication of voltage presence. Robust and reliable for industrial use.

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Digital Multimeters (DMM)

Measure voltage, resistance, and current. Provides numerical readout for precise confirmation of zero-voltage state.

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Non-Contact Voltage Detectors

Detect voltage without direct contact — useful for initial checks. Must always be confirmed with a contact tester.

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Pressure Gauges

Verify zero pressure in refrigeration systems and compressed air lines. Must be rated for the system being tested.

CAT Ratings

Test equipment is rated for specific installation categories (CAT I–IV). Always use equipment rated for the voltage and category of the system being tested.

CAT I Electronic equipment and secondary circuits

CAT II Single-phase receptacle-connected loads

CAT III Three-phase distribution, commercial lighting — most HVAC/R applications

CAT IV Utility connection and overhead lines

1.7.8 — Training Requirements

All workers who perform lockouts or work on locked-out equipment must receive full LOTO training. Other workers must receive awareness training.

🎓 Full LOTO Training

Recognition of hazardous energy sources
Type and magnitude of energy in the workplace
Methods and means of isolating and controlling energy
Lockout procedures for their workplace and equipment
Purpose and function of lockout devices
Limitations of tags (tags are not physical barriers)
Requirements for verification of zero energy state

👁️ Awareness Training (All Workers)

Understanding of LOTO procedures in the workplace
Prohibition against removing locks or operating locked-out equipment
Recognizing lockout tags and devices
Who to contact if a locked-out situation is encountered