Alex asks this question about an electrical installation in which the RCD test failed, yet the instrumental testing was OK. It has been answered by the ECA (Fire, Safety and security):
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Question: An RCD’s functional test button fails, but the instrumental testing passed. What guidance is there on this situation?
What would the manufacturers recommend?
Would this make the device or installation unsatisfactory?
Answer: The RCD test button should be checked periodically to ensure the effectiveness of the mechanical element of the RCD. I am not sure what the manufacturers will say about this, as they will all no doubt have different reactions.
However, Regulations 612.13.1 and 612.13.2 make reference to the 'effectiveness of any test facility incorporated in the device' and 'a functional test'.
If you are undertaking an Electrical Installation Condition Report (EICR), Section 4.8 of the schedule of inspections (BS 7671 page 423) requires this element to be checked and coded accordingly.
In this instance, I would bring this situation to the attention of the owner of the installation, as there is clearly something wrong with the RCD, and I strongly recommend that it be replaced.
I would also contact the manufacturer of the unit and seek their guidance, as they may well state that the device is now out of warranty.
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