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How to Carry Out a Safe Isolation Test on Your Boiler
In this video you will see:
- Identify the correct boiler circuit at the FCU and at the board
- Lock off and tag to prevent re-energisation
- Prove your tester on a known live source, test the circuit, then re-prove
- Confirm dead L-N, L-E, and N-E with a two-pole voltage indicator and proving unit • Final checks, reinstatement, and documentation tips Tools used:
- Socket & See two-pole voltage indicar
- Socket & See proving unit
- Lockout devices for FCU and MCB, with warning tags • Appropriate PPE and a record card
Safety and compliance
Follow Electricity at Work Regulations 1989 and use GS38-compliant leads and probes. Gas Safe TB118 requires safe-to-touch checks and a verified dead circuit before work. Do not rely on a multimeter for proving dead. Only trained, competent persons should perform these tasks.
Who this helps
Gas engineers, heating installers, and electricians working on domestic boilers who need a quick, repeatable, and defensible isolation method.
Disclaimer
Site conditions vary. You are responsible for competence, risk assessment, and legal compliance.