Correctly identifying isolation points is the foundation of every lock out tag out procedure. Isolating the wrong point, or missing a secondary energy source, can result in unexpected energisation causing serious injury or death. This talk explains how to identify all isolation points for a given task, the tools available to help, and the verification steps that must be completed before work begins.
Key Hazards
Electrocution from isolating the wrong circuit or energy source
Unexpected machinery start-up due to missed secondary isolation points
Stored energy release from hydraulic, pneumatic, or gravity systems
Incorrect identification of valves leading to chemical or steam release
Control Measures
Obtain and review the isolation schedule or schematic drawing before starting any isolation work.
Identify every energy source connected to the equipment including electrical, mechanical, and hydraulic.
Trace all pipework, cables, and control circuits back to their respective isolation points physically on site.
Label every isolation point clearly with the equipment name, permit number, and isolator identity.
Verify isolation by testing at the point of work using approved voltage indicators or pressure gauges.
Cross-reference isolation points against the asset register, P&IDs, or electrical schematics.
Use a second competent person to independently verify that all isolation points have been identified.
Record all identified isolation points on the permit to work before authorising the task.
Check for stored energy in capacitors, accumulators, or elevated loads and discharge before work begins.
Remember
Every energy source must be identified before isolation begins including stored energy
Isolation schedules and schematic drawings must be reviewed before any physical isolation
Always verify isolation at the point of work using approved testing instruments
A second competent person should independently confirm all isolation points are correct
Label every isolation point clearly with equipment name, permit number, and identity
Stored energy in hydraulic, pneumatic, or gravity systems must be safely discharged first
Applicable Legislation: Electricity at Work Regulations 1989 · PUWER 1998 · Health and Safety at Work etc. Act 1974 · DSEAR 2002