Stored Energy Isolation

Stored energy remains in systems after the primary power source has been disconnected and isolated.
Sources include compressed springs, pressurised hydraulics, pneumatic accumulators, and elevated loads.
Electrical stored energy exists in capacitors, UPS batteries, and charged busbars after isolation.
Gravity stored energy applies to suspended loads, raised platforms, and counterweighted mechanisms.
Thermal stored energy from hot surfaces, steam systems, and heated vessels causes burn injuries.
Stored energy can release suddenly and unexpectedly, causing fatal crushing, injection, and burn injuries.
Every LOTO procedure must identify all stored energy sources and specify how each is safely released.
Blocking, pinning, and cribbing are used to prevent gravity-stored energy from releasing during maintenance.
Hydraulic and pneumatic systems must be depressurised and checked at zero before work begins.
The Electricity at Work Regulations 1989 and PUWER 1998 require stored energy to be controlled.

Unexpected release	Stored energy releases without warning when restraints fail, causing crush injuries, amputations, and fatalities.
Multiple sources	A single machine may contain electrical, hydraulic, pneumatic, gravity, and thermal stored energy simultaneously.
Legal requirement	PUWER 1998 and EAW 1989 require that all energy sources, including stored energy, are controlled before maintenance work.

Do

Don't

Identify all stored energy sources before starting any LOTO procedure.
Depressurise hydraulic and pneumatic systems fully before beginning work.
Discharge capacitors and verify zero voltage before working on electrical systems.
Block, pin, or crib raised loads and platforms to prevent gravity release.
Allow hot surfaces and thermal systems to cool to safe temperatures before contact.
Verify stored energy has been released by testing or checking gauges at zero.
Include stored energy controls in every LOTO permit and method statement.
Restrain compressed springs mechanically before releasing any retaining fasteners.
Brief the maintenance team on every stored energy source present in the system.
Re-verify energy isolation if work is interrupted or the shift changes.

DON'T assume disconnecting the power source eliminates all energy in the system.
DON'T work under raised loads without mechanical blocking or cribbing in place.
DON'T open hydraulic or pneumatic connections without confirming zero pressure first.
DON'T touch electrical components without verifying capacitors are fully discharged.
DON'T release spring-loaded mechanisms without a mechanical restraint in position.
DON'T rely on pressure gauges alone; physically verify depressurisation is complete.
DON'T touch hot surfaces without confirming they have cooled to a safe temperature.
DON'T forget to include thermal, gravity, and spring energy in the LOTO plan.
DON'T start work on any system until all stored energy has been safely released.
DON'T remove blocking or cribbing until the system is fully reassembled and safe.

See also: LOTO Awareness | Verification of Isolation (Proving Dead)

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