Lockout-Tagout: Ensuring Safety with One Key and One Lock
Posted by Zing on Aug 29th 2023
In industrial operations and maintenance, Lockout/Tagout (LOTO) protects workers from hazardous energy—electrical, mechanical, hydraulic, pneumatic, chemical, and thermal. A cornerstone of an effective program is the “one key, one lock” rule: every authorized worker applies and controls their own lock and key.
Understanding Lockout-Tagout
LOTO is a structured process that isolates energy so equipment cannot start unexpectedly during service or repair. Below is a visual of the standard flow.
Identify energy sources and hazards for the specific asset.
Inform affected personnel that LOTO is beginning.
Power down and isolate all energy sources.
Apply lockout devices and personal locks; attach tags.
Bleed, block, vent, or discharge residual energy.
Try-start or test to confirm zero energy state.
Perform maintenance/repair with controls in place.
Each worker removes their own lock; re-energize safely.
The Significance of “One Key, One Lock”
This rule ensures that each authorized worker maintains full control over their personal safety. No one else can remove that lock or access its key.
Each worker is responsible for isolating and verifying energy control on the equipment they service.
Multiple locks = multiple workers. Everyone sees who is still working, preventing premature start-up.
No shared keys. No guessing. Equipment cannot be re-energized until every personal lock is removed.
Simplifies control—one worker, one key, one lock—reducing confusion and administrative mistakes.
- Issue uniquely keyed padlocks per person
- Use hasps for group lockout so all workers can lock on
- Include name, reason, and time on each tag
- Train and annually audit LOTO practices
- Share keys between workers or shifts
- Remove someone else’s lock without a documented emergency process
- Rely on tags alone without physical lockout devices
- Skip verification/try-start before service
Compliance reminder: Align your program to OSHA 1910.147 (Control of Hazardous Energy) and your site’s written Energy Control Procedures. Document training, inspections, and any group-lockout release steps.
Conclusion
“One key, one lock” is more than a rule—it’s a commitment to personal control and clear communication. By holding individuals accountable and preventing accidental re-energization, you strengthen your safety culture and protect every technician on the job.