Gomez Addams said:

It trips on the button

That doesn't depend on an earth connection in most, if not all, RCDs.

Gomez Addams said:

No justification was given for the C2. When asked he would not discuss it. He just stated it has to be below 200 ohms. 

I don't think there's a point in arguing this. In TT systems, Regulation 643.7.1 b) is used to verify effectiveness of automatic disconnection of supply (for protection against electric shock).

This first requires measurement of earth electrode resistance as per 643.7.1 b) (1). BS 7671 (Note to Table 41.5) and the relevant IET Guidance Notes all say that an earth electrode measurement exceeding 200 Ω indicates the earth electrode resistance is possibly not stable.

The next step of testing ADS in TT systems relying on RCDs, according to Regulation 643.7.1 b)(2), is to test the RCD. The guidance in IET Guidance Note 3 for RCD Test Method 1 (test between live conductor and cpc downstream of RCD) implies it may not be safe to conduct the test if the EFLI exceeds the maximum limits (in the case of earth electrode, that would imply check the earth electrode is stable before testing).

Therefore, it may be the case that the person carrying out the test considered it not safe to proceed with RCD tests. It would be a potential breach of health & safety legislation for them to proceed with the tests if they believed it was not safe to do so.

Perhaps there are two ways to proceed from here:

1. Carry out some work to reduce the earth electrode resistance (e.g. repair, replace, or supplement with a second electrode ... doesn't have to be a 'rod' but installing in accordance with BS 7430, at a suitable depth, is strongly recommended).
2. Get a second opinion.

You picked out it trips on the button. I also said it trips on RCD tests too, all of them, and in less than half the limit.

I didn't know until later when I spoke to my tenant that he had told her "he didn't have the right equipment with him to do all the tests". So what didn't he have? RCD tester?

Also, the reports say 25% of accessories sampled. Another of my tenants told me, he didn't see the electrician remove any fitting whilst he was there.

I have zero confidence in anything he has said or reported. I have been through these properties myself in minute detail. I have no doubts they are safe.

Gomez Addams said:

You picked out it trips on the button.

Because that makes no odds to testing for BS 7671 conformity, which requires two steps as I said:

1. Earth electrode test; and
2. Then, if safe to do so, RCD test.

Gomez Addams said:

I also said it trips on RCD tests too, all of them, and in less than half the limit.

I also said it may be considered unsafe to do that test, if the earth electrode test  (or a loop impedance test) is not satisfactory. The electrician has to abide by the Electricity at Work Regulations whilst at work ... that may or ,may not apply to yourself, and I'm not questioning that.

As far as BS 7671 is concerned, the electrician may have considered the verification for ADS failed at "step 1" and stopped there (which as I have said, may be difficult to argue with if one has no other knowledge of the installation, as is the situation for myself and other posters here).

I'm not sure why going round in circles will change anything ... BS 7671 has criteria in Regulation 643.7.1 b), which the electrician obviously considered are not met, and just pointing at "step 2" of the verification in Regulation 643.7.1 b) doesn't change the status of "step 1" of that Regulation (at least in the eyes of the original electrician).

Gomez Addams said:

I have no doubts they are safe.

Whilst I wouldn't want to contradict you, as you have knowledge of the installation, I am discussing the criteria in the Standard we are supposed to be inspecting and testing against?

Gomez Addams said:

I didn't know until later when I spoke to my tenant that he had told her "he didn't have the right equipment with him to do all the tests". So what didn't he have? RCD tester?

Also, the reports say 25% of accessories sampled. Another of my tenants told me, he didn't see the electrician remove any fitting whilst he was there.

I have zero confidence in anything he has said or reported.

I'm not sure there's enough to go on here for me to comment further, and of course you'd need to make your own decision on each of these things.

However, in your original post, you only questioned the RCD test ... you said you believed the criteria are met, but I think on that particular point, the electrician may have been following the criteria as stated in Regulation 643.7.1 for TT systems?

Gomez,

Im not really sure why you came onto the forum and asked for an opinion from other Forum members, many of whom are well known BS7671 Experts and have input into that standard as well as others. All you have done has discounted their advice and indicated in your post above that "I have no doubts they are safe"!! if that indeed is the case why not carry out the EICR's yourself and issue the reports and take the responsibility for what you are reporting? or If you feel that the EICR's have not been carried out correctly then raise a complaint with the local trading Standards Department over the quality of the inspectors EICR Report.

I have tested thousands of TT earthing systems over my career albeit within a flammable atmosphere installation, where we certainly depend on the three or sometimes four levels of RCD current and time cascading to ensure protection and compliance.

I would have raised an issue on any single electrode over 200 Ohms in value in fact in my specalised area of work we deliberatly state that any electrode giving a reading above 200 Ohms is likley to be unstable and actually indicate that no single electrode should be above 100 Ohms. So I agree C2 was likley a fair remark albeit FI would have been appropriate, was the ground conditions i.e wet, dry, cold, frozen mentioned when the test was carried out as if this reading was obtained when damp/wet then readings will only get worse as soil drys out.

Why ask for opinions then disregard and criticise those trying to assist on this forum.

GTB

I suspect that Gomez wants "us" to validate his opinion. Afraid that isn't going to happen.

I suspect that Gomez wants "us" to validate his opinion. Afraid that isn't going to happen.

Rubbish! Others have made far more helpful and useful critical comments.  The question was if the resistance is in spec and the trip times are adequate, where is the potential danger? Read what was written. He didn't do the tests by his own admission. Best practice guide 4 cites C2 for RCD not tripping. It says nothing about rod resistance above 200 ohms.

Furthermore, have any of you read the government guidance on landlords safety inspections? It's quite clear. The requirement is it "safe". EICR is not a requirement. It is a possible method. Also, compliance with the latest regulations is not a requirement. The IET wiring regulations have no force in law. They are not statutory. The IET is not an arm of government and has no official sanction.

That second paragraph is just plain nonsense. In the private rented sector, at least in England, there is a statutory requirement that an installation comply with BS 7671. See here if you do not believe me: https://www.legislation.gov.uk/uksi/2020/312/regulation/3

What is your evidence that the [earth rod] resistance is "in spec"? As far as I can see, it has not been measured properly.

Gomez Addams said:

The IET wiring regulations have no force in law. They are not statutory.

Agreed ... BUT:

1. BS 7671 is mandated by legislation (Regulation 22 of ESQCR) for the whole installation, if you have generation operating in parallel with the public distribution network (e.g. Solar PV).
2. BS 7671, as a British Standard, is used as evidence in court for relevant cases involving installations within its scope.

Gomez Addams said:

The requirement is it "safe". EICR is not a requirement. It is a possible method.

OK, but if one uses another method, worth being prepared to defend that position. At the moment, the view that reliance on the RCD without an effective means of earthing is OK goes against all the published guidance  (including BPG4 which you quote - see below).

Gomez Addams said:

The question was if the resistance is in spec and the trip times are adequate, where is the potential danger?

The guidance says there may well be, and I'm sorry if you don't like the fact that I've pointed out that the means of verification prescribed i n BS 7671 hasn't been met for this installation (and provided a credible reason why the electrician didn't carry out the RCD tests themselves).

Gomez Addams said:

Best practice guide 4 cites C2 for RCD not tripping. It says nothing about rod resistance above 200 ohms.

BPG4 actually says C2 for: 'Absence of a reliable and effective means of earthing for the installation.'

... it's the first entry under C2

As discussed, the technical guidance for inspection and testing, and BS 7671 itself, advises earth electrode resistance > 200 Ω may not be stable.

Apologies if you're offended by my opinion on this topic, but it's sadly not going to change without seeing the installation in question for myself.