Isolation (electrical)
Cutting a circuit or installation off from every source of , and securing it, so it's safe to work on. It's one of the four kinds of switching in BS 7671's Chapter 46, and the device has to be one that's suitable for the job. A light switch or stop button doesn't anything. Safe isolation is the wider procedure that also proves the circuit dead.
Using Isolation (electrical) in context
Reviewed
A distinction worth remembering
A control switch can stop equipment without isolating every source of energy. Safe isolation includes securing the isolation and confirming the absence of voltage with suitable equipment. A quiz response is preparation for supervised practice, not permission to work on a circuit.
Questions to take further
- How can I revise Isolation (electrical) beyond the definition?
- Explain what Isolation (electrical) describes, compare it with a related term and use it in a topic question. State any assumptions and what evidence you would need before applying the idea to real work.
Sources
- HSE: electrical safety questions — Isolation, competence and precautions before electrical work.
- HSE: GS38 test equipment guidance — Choosing and maintaining suitable low-voltage test equipment.
- IET: current BS 7671 edition and updates — BS 7671:2018+A4:2026 and the main subject areas updated by Amendment 4.
Where Isolation (electrical) fits in the learning path
The The Regs and Practice Papers section covers these units:
- Finding Your Way Round the Regs
- Protection & Selection
- What Amendment 4 Changed
- Timed Practice Papers
Curriculum mapping: C&G 2382-26 (BS 7671:2018+A4:2026).
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- Safe Isolation ProcedureSparks Basics
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- Safe Isolation — quiz previewFree · Sparks Basics
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Recall a related term
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The procedure that proves a circuit dead before anyone works on it. Prove the voltage indicator against a known source, isolate the circuit, secure the isolation with your own lock and tag, prove the point of work dead across all conductor combinations, then prove the indicator again. The final step is the one that catches a tester that died mid-job.
Safe isolation
Read the Safe isolation entryCompare related terms
Open a meaning to compare its role with Isolation (electrical), or follow its full entry.
Safe isolation
The procedure that proves a circuit dead before anyone works on it. Prove the voltage indicator against a known source, isolate the circuit, secure the isolation with your own lock and tag, prove the point of work dead across all conductor combinations, then prove the indicator again. The final step is the one that catches a tester that died mid-job.
Read the Safe isolation entryEmergency switching
Switching that cuts the power fast when danger is unfolding, by a control anyone nearby can reach and work at once, such as a stop button on a machine. It's one of the four kinds of switching in BS 7671's Chapter 46. It isn't isolation: stopping something in an emergency doesn't make it safe to work on.
Read the Emergency switching entryFunctional switching
Everyday on and off control of equipment in normal use, such as a light switch or a thermostat. It's one of the four kinds of switching in BS 7671's Chapter 46. Its job is control rather than safety, so don't treat a functional switch as isolation.
Read the Functional switching entryVoltage indicator
A two-pole instrument used to check for voltage between conductors during safe isolation. The user checks it on a known live source or proving unit before and after testing the circuit. A suitable indicator and sound probes matter because a false dead reading can expose someone to live parts.
Read the Voltage indicator entryA definition is a start. Using it in a real question is where it sticks.