Verification of Isolation (Proving Dead)

• Always prove dead using the three-step test sequence before starting work.
• Prove your voltage tester on a known live source before and after testing.
• Use approved test instruments that comply with HSE Guidance Note GS38.
• Verify all phases, conductors, and neutral are dead, not just one phase.
• Confirm mechanical stored energy has been released or safely restrained.
• Apply earths or short-circuit devices after proving dead where required.
• Record the proving dead test result on the permit to work.
• Repeat proving dead if there is any interruption to your work period.
• Ensure your test instruments are calibrated and within their service date.
• Only allow competent persons to carry out proving dead procedures.

• DON'T assume a circuit is dead because the isolator is in the off position.
• DON'T use a tester that has not been proved on a known live source first.
• DON'T skip the final prove step after testing the circuit being worked on.
• DON'T use non-contact voltage detectors as the sole means of proving dead.
• DON'T start work on any system until proving dead is confirmed and recorded.
• DON'T test only one phase and assume the others are also de-energised.
• DON'T use damaged, expired, or uncalibrated test instruments for proving dead.
• DON'T allow anyone other than a competent person to carry out these tests.
• DON'T forget to check for stored energy in capacitors and backup supplies.
• DON'T rely on indicator lights or control panel status to confirm isolation.

See also: LOTO Awareness | Electrical Isolation