Consumer Unit Replacement

[ban-all-sheds]

The CPC of the second ring would be "a ring with both ends connected at the origin". The CPC ring will have multiple joints (most or all at sockets etc.), and the fact that the conductors from the first and last joints to the 'origin' are shared with the first ring does not alter the fact that the second circuit's CPC is a "ring with its ends connected at the origin".

Err...

Yes.

Those two red lines look very much like "CPCs arranged in a ring with the ends joint at the origin", don't they?

They do.

Sorry.

 

[scousespark]

Good to see you.

Do you perhaps mean 'sockets' rather than 'circuits'? I would certainly expect an EICR to include at least some testing of every circuit in the installation, not just a 'sample' of circuits.

If you do mean sockets then, yes, I understand that that is the usual situation. However, perhaps I am over-demanding or over-cautious, but if the EICR were being done for me and the situation was such that the end-to-end continuity of a ring final circuit's CPC could not be tested, I think I would be more comfortable if I knew that it had been confirmed that each socket on the circuit had an earth connection.

Kind Regards, John

I meant circuit. In commercial/industrial installations it's common to test a sample of circuits and this may be carried out at a sample of points on the circuit. If there are complete records and the results are in line with previous tests, it's an acceptable practice to sign-off the inspection. If the results don't match, or there have been changes in the installation, then complete tests should be carried out. This is subject to a risk assessment. This would rarely apply to a domestic installation.

 

[scousespark]

I'm not advocating the practice, but, over the years, I've watched a lot of PIRs/EICRs being done on existing installations and have rarely, if ever, seen any sort of testing being done on each and every socket in an installation.

Kind Regards, John

When you have seen this, have you had access to any installation documentation? The inspector may have been comparing his results with those previously recorded to confirm that the circuit is okay.
If we were all cutting corners, I would expect a lot more electrical related injuries would be reported.

 

[JohnW2]

I meant circuit. In commercial/industrial installations it's common to test a sample of circuits and this may be carried out at a sample of points on the circuit. If there are complete records and the results are in line with previous tests, it's an acceptable practice to sign-off the inspection. .... This would rarely apply to a domestic installation.

Fair enough. I know nothing about, and was not talking about, commercial installations - and I would certainly be surprised if all circuits in a domestic installation were not tested.

If the results don't match, or there have been changes in the installation, then complete tests should be carried out. This is subject to a risk assessment.

Even in a commercial or industrial installation, testing only a sample of circuits has presumably got to be a gamble. The fact that no fault has arisen since the previous testing in a sample of circuits obviously does not preclude the possibility that faults have arisen in non-tested circuits - and it would need supernatural powers or a crystal ball, rather than a 'risk assessment', to alter that inevitable truth. By their very nature, faults can arise 'unexpectedly'.

Kind Regards, John

 

[JohnW2]

When you have seen this, have you had access to any installation documentation? The inspector may have been comparing his results with those previously recorded to confirm that the circuit is okay.

No, not usually. This question has already been asked and, as I wrote ...

... and that's what worries me a little about what I have observed. Most of the EICRs I see done are on installations of unknown history, and often in quite iffy condition - and it concerns me that, unless I intervene, it is so common (in my experience) for all sockets not to be tested, even by electricians who otherwise seem to be very competent and conscientious. However, maybe I've just been 'unlucky' in whom I have observed! .... I recently saw a case where I already knew that one of the sockets "didn't work", and the initial EICR did not pick that up (although that got changed after I "spoke up"!).

If we were all cutting corners, I would expect a lot more electrical related injuries would be reported.

I think you are probably over-estimating the extent to which EICRs reduce electric-related injuries in domestic installations, particularly given how infrequently such inspections are often undertaken on such installations. It also depends upon what corners are being cut - in the context of this discussion, I would have thought that an injury resulting from failure to test every socket in an installation would be an extremely rare event, therefore such omissions would probably not have much impact on injury statistics.

Even so, I'm obviously not advocating 'cutting corners' ("if an EICR is worth doing, it's worth doing properly"), and would not cut them if I were doing it myself - I am merely reporting what I have observed.

Kind Regards, John

 

[scousespark]

Fair enough. I know nothing about, and was not talking about, commercial installations - and I would certainly be surprised if all circuits in a domestic installation were not tested.
Even in a commercial or industrial installation, testing only a sample of circuits has presumably got to be a gamble. The fact that no fault has arisen since the previous testing in a sample of circuits obviously does not preclude the possibility that faults have arisen in non-tested circuits - and it would need supernatural powers or a crystal ball, rather than a 'risk assessment', to alter that inevitable truth. By their very nature, faults can arise 'unexpectedly'.

Kind Regards, John

The major cause of faults is alterations to a circuit. In commercial/industrial, it's rare that changes are not recorded. In domestic, the opposite is true. Unexpected faults can occur, but if EICRS were missing loads of faults, we would see a lot of electrical incidents being reported. I don't think this is the case, unless there is the result of some statistical analysis somewhere out there.

 

[JohnW2]

The major cause of faults is alterations to a circuit. In commercial/industrial, it's rare that changes are not recorded.

I'm sure that's true, but that's rather different from the sort of 'spontaneously-occurring fault' I was thinking about. When you test just a sample of circuits in a commercial/industrial installation, do you not even test, say, RCDs/RCBOs on the 'non-sampled' circuits?

In domestic, the opposite is true. Unexpected faults can occur, but if EICRS were missing loads of faults, we would see a lot of electrical incidents being reported. I don't think this is the case, unless there is the result of some statistical analysis somewhere out there.

As I've just written, I think you are probably over-estimating the extent to which EICRs result in a reduction in incidents/injuries. Apart from anything else, I would have thought that 'invisible' or 'latent' faults are probably relatively rare, since the majority of significant faults probably present themselves in some way and are therefore remedied. Even potentially dangerous 'invisible/latent' issues (e.g. inadequate/absent earthing/bonding, unearthed metal accessories, faulty RCDs etc. etc.) taht should be picked up by an EICR would nearly always persist for decades without resulting in any i ncidents/injuries.

Again, I'm not advocating failure to have EICRs done regularly (and properly), but ....!

Kind Regards, John

 

[scousespark]

I'm sure that's true, but that's rather different from the sort of 'spontaneously-occurring fault' I was thinking about. When you test just a sample of circuits in a commercial/industrial installation, do you not even test, say, RCDs/RCBOs on the 'non-sampled' circuits?
As I've just written, I think you are probably over-estimating the extent to which EICRs result in a reduction in incidents/injuries. Apart from anything else, I would have thought that 'invisible' or 'latent' faults are probably relatively rare, since the majority of significant faults probably present themselves in some way and are therefore remedied. Even potentially dangerous 'invisible/latent' issues (e.g. inadequate/absent earthing/bonding, unearthed metal accessories, faulty RCDs etc. etc.) taht should be picked up by an EICR would nearly always persist for decades without resulting in any i ncidents/injuries.

Again, I'm not advocating failure to have EICRs done regularly (and properly), but ....!

Kind Regards, John

I'm not over-estimating anything as an EICR will reduce nothing, even if there are present dangers, as there is no pressure on the customer to remedy any faults. I am just saying that, sampling is an industry standard practice. If there were lots of electrical incidents being reported, I'd expect we would be told to carry out total tests.

 

[JohnW2]

I'm not over-estimating anything as an EICR will reduce nothing, even if there are present dangers, as there is no pressure on the customer to remedy any faults. ....

I must have misunderstood you, then, when you appeared to be saying that not doing EICRs, or not doing them properly, would result in "a lot" of "electrical related injuries" and "electrical incidents"....

If we were all cutting corners, I would expect a lot more electrical related injuries would be reported.

.... In domestic, the opposite is true. Unexpected faults can occur, but if EICRS were missing loads of faults, we would see a lot of electrical incidents being reported.

Kind Regards, John
Edit - what's happening? One of my quotes has disappeared, and I can't 'edit it back'!
Edit2 - sorted by manually inserting the missing quote, but something's still wrong with the software!

 

[ban-all-sheds]

Anyway - back to the testing problem.

View attachment 139173

I agree, that end-to end testing would not pick up this:

Or this:

But nor would it pick up this:

In all these cases, the only way to be sure that there is a cpc at every point is to test at every point. There are no shortcuts.

 

[JohnW2]

Maybe I should have put blobs on my wires to remind people where the terminals/'joins' are. Little is impossible, but the probability of a pair of CPCs conductors coming out of a socket terminal but remaining connected together is incredibly low. The same very low probability also applies to L & N, so is it being suggested that one should not bother undertaking end-to-end continuity testing of the L & N rings, in favour of just measuring resistances to the 'origin' from each and every socket?

 

[ban-all-sheds]

E-E testing is a good initial check.

Is it being suggested that if E-E is OK one should not bother checking each outlet, and just assume that a cpc is present everywhere?

 

[JohnW2]

I have not suggested anything, but have noted that I have observed a good few people undertaking EICRs not 'bothering' to check the CPC at every socket on a ring final if the CPC ring has end-to-end continuity.

 

[ban-all-sheds]

Then they risk missing a problem which could kill someone.

 

[Adam_151]

No EICR is ever 100%, if it were to be so, then the costs would be prohibitive and we would just have no EICRs instead as it just would not happen, the cost / benifiet of it just wouldn't stack up, the client could spend the money elsewhere on something that would have a bigger possitive effect on H&S.

The job of an inspector is to identify as close to as 100% of problems for fee that allows the client to have it done at all, and not just put it off as something that is too expensive.

Now, personally speaking, I like to bang the three neon tester in everypoint I can on socket outlet circuits, while taking earth loop at a number of points around the ring, but there are always going to be sockets that can't be found, sockets that are not accessible, or because this is normally being done outside of the shutdown window allowed... bits of kit that can not be unplugged.

A good inspector will adjust the level of tests done according to the overall impression of the installation, a 40 year old installation with signs of DIY work warrants more scrutiny then a five year install tidiliy installed with an EIC available in the O & M manual.

You have to remember that in the EICR world you are competing with charlations who will come in for a lowish fee, carry out a few earth loop tests, make a load more of them up, or copy from the previous report, write >200 meg in every column for insulation resistance, not check the main bonding and not look above the suspended ceiling for the connector block joints hanging loose. In some cases the schedules do not properly match the distribution boards on site. The client gets a satisfactory report and is happy that its done for another five years.

It happens a lot more than you might think, commericial buildings, local authority facilities, care homes, schools theres a lot of EICRs out there which are only usful as toilet paper (and sometimes not even that, as the client has laminated them!)

Edit: I'm beginning to sound like JP here.... I just seem to become more jaded the more EICRs I see!