Earth bond from incoming supply?

[A.Lee]

I had an assessment today for my sparky registration. The Inspector checks all the earth bonds, and numerous other things. Anyway, he pointed out that my earth bond at the point the cables enter the house is not correct. Currently it has a 'Tenby' clamp type earth connector on it - the same sort as used on pipes. He said this the worng sort of connector, as it crushes the cables, and should be soldered, or a special clamp supplied by the Electric Company. I said I would sort it out, he said no, as it is the power suppliers responsibility, and I should not touch it.

So I rang them, they do not do earth repairs, and I must get an electrician in to do it!

So what do I do? And what type of clamp should be used?

When I moved here, it was just a single strip of copper ring with a nut and bolt holding the two sides together. (I didnt remove it, the elec board did when they replaced the CU 14 years ago.) Are these still available?

Ta Alan.

[Tim Watts]

I think they either misunderstood or are fobbing you off. An electrician is not supposed to touc anything before the meter, and secondly they have a duty to provide an earth within spec unless you have a TT system (in which case the supply no earth).

Which company is it?

You could try their emergency number[1] and tell them your electrical inspection has noted a fault on the supplier's earth - that should get someone out pretty fast.

[1] an inadequate earth counts as an emergency. However, such things are not unheard off - but if you have it in writing and play the "dumb consumer" there's not much they can whine about - except maybe at the inspector's enthusiasm!

Cheers

Tim

[Dave Osborne]

It's the DNO's cable and you might think it's the DNO's responsibility to supply a proper earth connection to their cable, but apparently it's not.

See this document (sections 8.4, 8.5) for further info:

in mind from the flowchart in Appendix A that they may cut off your supply...

Call them back and persuade them to fix it, or switch to a TT installation, or approach the lads from the DNO when they're in your area and scrounge an earth terminal kit, or call an outfit like Thorne & Derrick (cablejoints, see below) and see what they say, or call a largish firm of electrical contractors in you area who may have come across this problem before and know how to get it fixed.

And what type of clamp should be used?

A proper one suitable for the type of cable you have. If it's a paper-lead cable, then something like this:

When I moved here, it was just a single strip of copper ring with a nut

Well they should have reinstated it, unless they've changed you to a TT supply and are not providing you an earth. You should ask them this (i.e. what type of earthing they think you have) when you call back.

[js.b1]

Anything pre-meter is DNO property.

If I recall the ESQW uses the word "reasonable"; once a DNO has provided an earth they must maintain it where reasonably possible. A bit like "reasonable" in getting a board fixed "it is ok if it has 3 screws".

As mentioned an EC clamp can crush PILC cable - lead sheath (1-1.2mm?), oil saturated paper, copper. Considering the lack of protective equipment (flash) fitting one is not a good idea. DNO staff had a habit of fitting EC clamps to loop-in supply PILC cables (linking supply & neighbour) in the 1980s, but their metering staff in the 1990s had a habit of taking one look and walking out the door. Can not blame them because bending PILC tails back and forth with a clamp on them would probably make most people nervous.

Strange how National Grid will turn up without question to fix a fault, but getting a DNO to do pretty much anything is like sitting in call waiting for god "you are position nine billion...".

[js.b1]

That sounds like the old clamp prior to plastic cutouts?

[Andy Wade]

Nothing, I suggest. There must be millions of TN-S earthing connections like this, despite the use of BS 951 clamps on PILC cables now being a deprecated practice. Unless it is loose or the Ze reading is excessively high I'd leave it alone.

[Andy Dingley]

Is the database remotely accurate at recording this?

I ask because I've spent the last 3 months wrangling with that database (after the =A31500 bill from the utterly inept Good Energy). My own record now has the same meter serial in use on two different MPANs, at two different postcodes, so I don't have a great deal of faith in it.

[Andy Dingley]

Separate question - what does the colour coding on these mean? I've got them in silver, red and blue. There appears to be no difference, or even a size difference.

[Tim Watts]

EDF told me in writing (as they are legally obliged to do if asked) that I had TN-S. My Ze reading however was 0.18 Ohms which made me suspicious

- so when the bloke came to pull the cutout fuse, i asked him to check. One cover off revealed a fairly modern TN-C-S system!

Dare say round here it was TN-S once, but there you go...

[Tim Watts]

Blue is for external use (ie weather proof, eg on an external gas pipe as I have) which you could use inside of course. Silver the regular jobbie for inside only. Not sure about red - never seen one.

[ARWadsworth]

[Piers Finlayson]

Which department at EDF did you speak to do get this? I've struggled to get the same info out of SP.

[Tim Watts]

I buggered about a lot until I spotted a phone number for "Technical" on the IET forums. Rang that, got asked where I found the number then they proceeded to answer my various questions sensibly (if wrongly - but that's not exactly the bloke's personal fault if the record keeping was s**te, especially in a period overlapping nationalised/privatised).