James White said:

The ECIR has identified that there is no evidence of 6 monthly RCD/RCBO functional tests (there are labels stating last RCD instrument test about 2 years ago) and marked this down as a C2, surely this would only be a C3? 

Surely this is between the Duty Holder and/or the person ordering the inspection & test, and the organization who carried out the inspection and test?

It's probably true to say that no-one can offer a definite opinion without seeing the installation, relevant documents, and contract.

Further, even the codes themselves are only guidance in BS 7671. Even if we use industry guidance, coding is only a guide ...

However, for any C1 and/or C2 provided, then it could be interpreted that BS 7671 requires the specific non-compliances with requirements to be identified ... depending how you read 651.2 (vi) ... How could you identify the non-compliance against the relevant requirement(s) without reference to the relevant requirement(s)?

(I know this last statement is perhaps controversial, and examples in guidance don't always show this).

If anything a C3 as you can see from table 3.5 in GN3, it would be recommended as an improvement. 

John Peckham said:

The user test facility tests the RCD at 2 x I delta n so should be done after the instrument test.

The current 2022 9th Edition of GN3 (Section 2.6.18) recommends the user test button is pressed before instrument test. It provides a reason why.

Basically, the test button uses "RCD test method 2" where a fault current is not returned to the protective conductor, but to one of the upstream live conductors. No-one else will be put at risk when the test button is pressed.

However, if RCD test method 1 is used, a voltage is present on the protective conductors of the installation until the RCD operates ... or the test instrument terminates the test. The voltage on the protective conductors may be limited by a test instrument to BS EN 61557, but:

• This is not guaranteed to protect everyone; and
• The voltage is not present when the test button is pressed (because it's 'Test method 2').

In addition, 'Test method 1' isn't possible for IT systems that use RCDs, for example.

Hi, if the test button fails to operate the RCD should you not proceed with the instrument test ? 

The test button is a zig-zag test, bridging between outbound live and inbound neutral or vice versa, and does not verify or requite  a CPC. However, being a higher test current than the minimum it may 'unstick' a mechanical RCD that would otherwise have failed a low current test.

If nothing happens when you press the 'T' button or equivalent, then your next act is to order up a replacement RCD/RCBO

You can still do a metered test if you like, but only on a modern meter that stops the test current before the test has run long enough to be dangerous to anyone downstream,

As the RCD has to be changed the test result is a bit academic.

Mike

Hi Mike. This is exactly what I do if the test button doesn’t operate. I have always marked it down as a fail and recommend it’s replaced without carrying out any further tests.

Andrew

Thank you Danie, lf quote "absence of an RCD specified for additional protection" is only a C3 then how possibly can you put the absence of evidence of 6 monthly functional tests down as a C2?

We are now carrying out biannual function tests and yearly documented instrument tests at 1xI∆n. I just can't accept a C2 for lack of evidence of RCD function tests, as almost every house in the UK would get C2 due to this.

I don't agree its a C2, I'm an NICEIC qualified supervisor and I wouldn't mark it down as anything due to the fact there is no requirement from BS7671 to record the functional test. I would recommend internal documentation to record it as this will help with auditing purposes. The test should be sufficient, if it fails to trip when the test button is pushed then obviously will require replacing. BS7671 also recommends a test of every six months but this can be more frequent depending on the installation and design requirements. I would question the electrical contractor as to why they believe that is a C2 as it is not potentially dangerous in my opinion.

Agree, I think almost every one on here feels that the original C2 - if it all works, and the lack of test records is the only problem- is seriously overdoing it.

The discussion seems to have expanded to consider  if even giving a C3 or out of scope and just an advisory comment in the cover letter is best.

M.

AMK said:

Hi, if the test button fails to operate the RCD should you not proceed with the instrument test ? 

I wouldn't proceed with an "RCD test method 1" (fault current returned to cpc) test ... the RCD needs to be replaced anyway if the built-in test button doesn't operate it. If it's an internal electronics fault with the RCD, testing further could cause thermal damage (something might go "pop" or worse).