Supply type identification and opinion on earth loop reading

[Iggifer]

That cert is for another install! It says 25mm tails and tn-c-s neither of which match your photos.

Well, they're 25mm² from the Henley's to the main switch at least!

 

[JohnW2]

I've spoken to the previous owner and they've forwarded me the two certificates of installation and it seems that actually the supply is TN-C-S, confirmed on both.

As JohnD has said, something is wrong. The Minor Works cert says that the Zs of the new circuit was 0.4Ω in 2012. That would not be unreasonable if it were TN-C-S, but the Ze then must have been less than 0.4Ω, which is obviously very different from the recent 200Ω measurement.

Either, as JohnD has suggested, those certificates relate to a different installation or else something fundamental has changed (or 'gone wrong') in the past 5 years.

Kind Regards, John

 

[Iggifer]

Shocking cert as ever though.

>200Ω IR on Line to Line
RCD information filled in in Main Switch section despite filling in 60947-3
Nominal voltage wrong
Apparently the circuit is protected by an 80A 60898
No amendment version filled in
Two circuits modified, one MWC
WTH is reference method 1
No decimal places for Zs or RCD times
Used model number for RCD type



Edit: d'oh, didn't see it was two certs. Well, neither is well filled in!

 

[John D v2.0]

Maybe every installation gets the same cert with the same figures? Just fill it in back at the office. Who's going to know?

 

[flameport]

pic of one of the "mains" tails next to a core from a 10mm 3-core SWA (for size, looks like 16mm to me?).

The red and black wires should have 2 layers of insulation (or insulation and an outer sheath for those that care), so would appear larger on the outside than the piece from the SWA.
Either they are 10mm, or if larger they may only have single insulation.
In any case they are certainly not 25, and there is no TN-C-S earth (or any other kind) evident at all.

The two certificates have a number of common blunders on them, but that aside, the first one is an EICR - the wrong document for a CU install or rewire.
Both claim it's TN-C-S which it obviously isn't - and it's difficult to see how it could have been before, yet isn't now - those black/red wires and the black fuse are probably decades old.
The documents either relate to some other installation, or both of the individuals were completely incompetent, not only stating it was the wrong type, but also not bothering to test it either.

200 ohms on the test device probably meant >200, it's ridiculously unlikely it would be exactly 200.
200 is far too high anyway, under 100 would not only be desirable but also expected.

Essentially he's now advised that he cannot carry out any work until this is addressed as effectively the supply is not earthed & that reading is effectively open circuit.

They are correct.
It shouldn't even be energised with no earth.

 

[Muzza80]

Ok so thanks for all the replies.

So what should I do? Contact the supplier SP Energy Networks and have them assess it?

 

[flameport]

Contact the supplier SP Energy Networks and have them assess it?

Definitely - to establish what type of supply you have got, whether it can be changed to TN-C-S, and even if not, have those red/black thin wires replaced with something more suitable.

If TN-C-S is not available, you will need to get an earth rod/electrode installed as soon as possible. It is not safe to leave the installation in it's current state.

You should also have the MCBs in that consumer unit checked as they were subject to a recall https://www.electricalsafetyfirst.o...2012/02/electrium-miniature-circuit-breakers/
and while the recall was before the alleged date of your installation, it's possible that defective stock was still around and could have been installed then.

If it is converted to TN-C-S, the bonding to gas, water will also need to be replaced, as the minimum size will then be 10mm², rather than the 6mm² it has now.

 

[Muzza80]

Definitely - to establish what type of supply you have got, whether it can be changed to TN-C-S, and even if not, have those red/black thin wires replaced with something more suitable.

If TN-C-S is not available, you will need to get an earth rod/electrode installed as soon as possible. It is not safe to leave the installation in it's current state.

You should also have the MCBs in that consumer unit checked as they were subject to a recall https://www.electricalsafetyfirst.o...2012/02/electrium-miniature-circuit-breakers/
and while the recall was before the alleged date of your installation, it's possible that defective stock was still around and could have been installed then.

If it is converted to TN-C-S, the bonding to gas, water will also need to be replaced, as the minimum size will then be 10mm², rather than the 6mm² it has now.

Thanks for that I'll get straight on to them.

A little more information has come in from the previous owner via email, the floors are solid concrete but apparently the "main supply does come in there" and it's definitely the documents they got for those jobs, their name and address is on one of the ones I posted and on another page (9 pages total) for the rewire/cu test.

Interestingly, that picture of the supply, if you look to the wall it looks to have been filled both underneath and at the right side, could the main supply be in behind that wall and they've just filled in over the top after getting access they needed, or perhaps it wasn't filled at the point the electrician did this report (the full house underwent a back to brick refurb around the time of the certificate so could have been hidden afterwards?) In which case, could the earth "tap" on to the main neutral (assuming it IS TN-C-S) be in behind there too?

Nightmare this, glad I found it though, if it wasn't for wanting to take power to my big shed I'd probably never have known!

 

[Muzza80]

Just an update to this if anyone's interested.

So I've been on to SPEN they've been out and have had to get access to the other 3 houses in the block (I'm an end terrace of 4)

Turns out that of four houses (assumed the other end terrace) only one has the main cable head/cutout and this is a looped supply from one of the other properties and there likely is no (and never has been) any earth, the cables are original from 1953 when the houses were built.

They're now talking about upgrading the supply in that house, from the road, and then taking a large cable up, into the loft, across to my property and down, through my stairs/hall and into the meter cupboard. Essentially upgrading the "looped supply" with bigger cable and an earth and leaving me with an unsightly cable running the full wall from my upstairs ceiling down to the ground floor and into my cupboard.

Obviously I suggested this was less than ideal to have some horrible black cable running inside my house and can they not give me a new supply directly from the street, the guy laughed and said they wouldn't do that as it's too expensive to do it for all 4 houses individually.

Where do I stand with this? Do I have to accept this upgrade as they suggested they would do it or would I be within my rights to expect a new supply from the road?

Any ideas?

Cheers!

 

[Iggifer]

You could PAY for a new supply from the road, but I suspect anything they will do for free will be as they want to do it.

You could at least trunk it down the wall - you can't bury it as it's a) theirs and b) it's best for people to know where it is - drilling a service cable is a whole different kettle of fish to drilling a final circuit. Chances are it wouldn't be in a safe zone anyway.

I would have thought 50x50 PVC trunking would be fine unless anyone else thinks bigger?

Would be easier for you if you had it on the wall before they come and then just ask them to run it down that. Will look a damn sight better than a bit of split con cleated down the wall

 

[Keithmac]

Does that mean they lied on the certificates for the CU install etc?.

 

[Muzza80]

Does that mean they lied on the certificates for the CU install etc?.

Looks that way, 16mm2 main earth cable into the CU is, as far as I can tell, connected to absolutely nothing :/

I've Ze tested this myself on a new Fluke 1652c I bought for testing my outbuildings installations and it just gives error4 (fault voltage), Ze test at a friends property is fine so not a lead/tester issue.

 

[Keithmac]

That's unbelievable then!, as you say it's a stroke of luck you had the electrician in to price the job up who found that fault.

I'd honestly take that further, could have been potentially fatal.

 

[Muzza80]

That's unbelievable then!, as you say it's a stroke of luck you had the electrician in to price the job up who found that fault.

I'd honestly take that further, could have been potentially fatal.

What I do find odd is that on page 6 of the rewire check / CU install it has listed all the checks for the supply cables and earth listed as C3, requiring improvement, yeah no ****

 

[Iggifer]

What I do find odd is that on page 6 of the rewire check / CU install it has listed all the checks for the supply cables and earth listed as C3, requiring improvement, yeah no ****

But then 3.4 & 3.5 are ticked. Disgraceful