Dead Testing vs Live Testing
The test sequence reduces risk: prove the installation is correctly connected while dead, then energise only for tests that require a live supply.
Initial verification is deliberately ordered to find wiring and protective-conductor errors before exposing anyone to an energised installation. Dead tests normally establish continuity, insulation resistance and polarity before live measurements such as loop impedance, RCD operation and functional checks.
This is practical guidance for competent electricians. Assess the actual installation, follow the current edition of BS 7671 and manufacturer instructions, and stop where the work cannot be completed safely.
Key takeaways
- Agree the scope and make the installation safe before starting work.
- Use a controlled sequence rather than relying on a single reading or visual assumption.
- Record the actual result, limitation or action taken while it is still traceable.
- Check the result against the design, protective measures and equipment instructions.
- Issue the appropriate certificate or report when the work is complete.
Scope the work first
Initial verification is deliberately ordered to find wiring and protective-conductor errors before exposing anyone to an energised installation. Dead tests normally establish continuity, insulation resistance and polarity before live measurements such as loop impedance, RCD operation and functional checks.
Method
Plan the sequence, isolate and prove dead, complete and record the dead tests, then inspect the work before controlled energisation. Keep access controlled and use safe working practices for any required live test.
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Checks and common pitfalls
Do not rush to a live loop or RCD test because a circuit appears complete. Incorrect polarity, missing CPCs, exposed conductors and unprotected test leads are hazards that the dead-test stage is meant to find.
Record and hand over
Keep test results in their logical order and note any departure, limitation or staged energisation. If the installation cannot safely proceed to live testing, leave it isolated and report why.
Keep the evidence with the job
Record readings, limitations and remedial actions as you work. A clear certificate or report protects the client and makes the next visit easier to manage.
From guidance to action
Frequently asked questions
Are all tests completed dead?
No. Some verification and functional tests need the supply energised, but they follow the dead-test stage and should be planned and controlled accordingly.
Can I rely on a standard rule of thumb?
No. The installation method, supply characteristics, equipment instructions and the current requirements all affect the correct decision. Use the guide as a workflow, then assess the actual job.
What should be recorded?
Record the scope, results, limitations, observations, remedial work and the certificate or report appropriate to the work carried out.
Related guides
Initial Verification: The BS 7671 Testing Sequence
The correct dead-then-live testing sequence for initial verification, step by step.
Safe Isolation Procedure
The step-by-step safe isolation procedure, proving dead with a GS38 tester, and locking off.
Insulation Resistance Testing
Test voltages, minimum acceptable values, and how to test insulation resistance safely.
