Electrical Isolation

Electrical isolation means disconnecting a circuit from its energy source so that it cannot be accidentally re-energised.
The Electricity at Work Regulations 1989 require safe isolation before any electrical work, testing, or maintenance.
Isolation must be carried out by a competent, authorised person using an approved isolation procedure.
The safe isolation procedure follows five steps: identify, isolate, lock, prove dead, and permit to work.
Proving dead means testing the circuit with a voltage indicator that has itself been proven with a known live source.
A proving unit or known live source must be used to confirm the voltage indicator is working before and after testing.
Each person working on the isolated circuit must apply their own personal padlock to the isolation point.
Adjacent live circuits near the work area must be identified and barriers or insulation installed to prevent contact.
Stored energy in capacitors, UPS systems, and battery supplies must be discharged after isolation before work begins.
Re-energisation requires a formal procedure ensuring all workers are clear, locks removed, and the area is safe.

Prevent electrocution	Accidental re-energisation of a circuit while someone is working on it causes electrocution — isolation physically prevents this.
Prove dead	Testing with a proven voltage indicator is the only way to confirm a circuit is truly dead — visual checks are not enough.
Personal lock	Each worker's individual padlock ensures the circuit stays isolated until every person has completed their work and removed their lock.

Do

Don't

Follow the five-step safe isolation procedure for every electrical isolation.
Prove your voltage indicator is working using a known live source before testing.
Test the circuit to confirm it is dead, then re-prove the indicator after testing.
Apply your personal padlock and tag to the isolation point before starting work.
Identify and protect against adjacent live circuits near your work area.
Discharge stored energy from capacitors, batteries, and UPS systems after isolation.
Use a multi-lock hasp when more than one person is working on the same circuit.
Ensure only authorised, competent persons carry out electrical isolation on site.
Follow the formal re-energisation procedure before restoring power to the circuit.
Record the isolation on the permit to work and keep it displayed at the work location.

DON'T work on any electrical circuit without completing the safe isolation procedure.
DON'T test for dead without first proving your voltage indicator on a known live source.
DON'T assume a circuit is dead because the switch is off — always prove dead.
DON'T start work without applying your personal padlock to the isolation point.
DON'T ignore adjacent live circuits — accidental contact causes electrocution.
DON'T forget stored energy — capacitors and batteries remain live after main isolation.
DON'T share locks or allow someone else to lock off on your behalf.
DON'T allow unqualified persons to carry out or reverse electrical isolations.
DON'T re-energise circuits until all locks are removed and the area is confirmed clear.
DON'T work on live circuits under any circumstances — live working is prohibited on site.

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

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