Continuity Testing Guide: R1+R2, R2 and Ring Finals
Continuity testing proves the protective path is complete before live testing begins — but only when the circuit has been identified and isolated correctly.
Continuity tests establish that line, neutral and CPC paths are complete and correctly connected. The chosen method differs between radial circuits, ring finals and circuits where the CPC cannot be conveniently tested end to end.
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
Continuity tests establish that line, neutral and CPC paths are complete and correctly connected. The chosen method differs between radial circuits, ring finals and circuits where the CPC cannot be conveniently tested end to end.
Method
Isolate, prove dead and disconnect sensitive equipment where needed. For radials, measure the relevant end-to-end paths; for rings, identify all legs, obtain end-to-end values and make the prescribed cross-connections before recording representative readings around the circuit.
Doing this on a job? R1+R2 calculator — part of TradePlanr. Free to start, no card needed.
Checks and common pitfalls
Unexpectedly high, low or uneven values can indicate a loose connection, incorrect conductor identification, parallel path or damaged cable. A satisfactory-looking number is not enough if the test method or circuit identification was wrong.
Record and hand over
Record the measured values in the schedule of test results and use them with Ze to support the Zs assessment. Label and reconnect conductors carefully before proceeding to insulation resistance and polarity tests.
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
Can R1+R2 replace a Zs test?
No. R1+R2 is a dead-test result used with the external earth fault loop impedance to assess the circuit. The applicable verification method and recorded evidence must support the final protective-measure assessment.
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
How to Test R1+R2 on a Ring Main
The three-step ring final continuity test, cross-connections and the readings that prove it.
Safe Isolation Procedure
The step-by-step safe isolation procedure, proving dead with a GS38 tester, and locking off.
Earth Fault Loop Impedance Explained (Ze, Zs & Zdb)
What Ze, Zs and Zdb mean, how the fault loop works, and how to measure and verify it against BS 7671 limits.
