RCD Testing Procedure (BS 7671)
Test an RCD in a controlled order, confirm it operates within its required characteristics, and record the result against the correct circuit.
RCD testing verifies that additional protection and fault protection operate as intended. Start by identifying the device, its rated residual operating current, circuits affected and any equipment that could be disrupted by the test.
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
RCD testing verifies that additional protection and fault protection operate as intended. Start by identifying the device, its rated residual operating current, circuits affected and any equipment that could be disrupted by the test.
Method
After safe preparation, use a suitable tester at an appropriate point on the protected circuit. Carry out the prescribed half-rated, rated and higher-current tests in the required polarities where applicable, then use a ramp test only where it adds useful diagnostic information.
Doing this on a job? EICR Certificate — part of TradePlanr. Free to start, no card needed.
Checks and common pitfalls
A device that will not reset, trips unexpectedly, protects the wrong circuits or produces doubtful results needs investigation before certification. Do not overlook standing leakage, borrowed neutrals, electronic loads and the consequences of interrupting safety-critical equipment.
Record and hand over
Enter device identity, rated IΔn, test current, trip times and test location in the schedule. Restore the installation, confirm essential loads are operating and explain any limitation or remedial action to the duty holder.
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
Should an RCD trip at half its rated residual current?
The expected operation depends on the test being applied and the device characteristics. Use the current BS 7671 requirements and your instrument instructions rather than treating one result in isolation.
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
Safe Isolation Procedure
The step-by-step safe isolation procedure, proving dead with a GS38 tester, and locking off.
RCD Keeps Tripping: Causes and Fixes
A structured method for tracing why an RCD trips — from nuisance tripping to real faults.
Schedule of Test Results Explained
Every column on the schedule of test results, what each reading means, and how to fill it in without gaps.
