Earth bonding at Consumer Unit.

I've been helping a friend sort out some of the electric's in their house.

They are at the stage of installing a new CU, bringing all the earth bonding up to scratch and then sorting out the main earth connection.

They are installing the new CU in a new location to a bit to get more space (to the other side of the wall from the meter and current fusebox).

Main earth bonding to the incoming gas and water services is being renewed, but we weren't sure where to terminate this - run it back to the CU or install some sort of earth terminal near the meter and then run the bonding cables, and the earth from the CU back to there. The latter makes more sense to me, but I can't see it really matters.

Re the earth connection, currently the installation has been earthed via the lead mains water pipe, once the works are done, he intends to get the earth connection made properly by the supply co. The supply presumably dates back to the late 1930's when the house was built and that the earth would likely be TN-S (underground supply, in town).

Does he just make all his connections, then contact supply co. to come and make the final earth connection?

Reply to
chris French
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I'd use a separate earth block near the incoming cut out.

Yes, provided the supply company has agreed to provide one. Otherwise, it is earth rod and 100mA time delay RCD time.

Christian.

Reply to
Christian McArdle

The Regs/OSG have a firm opinion - a Main Earthing Terminal outside the CU is strongly preferred, if not mandated: it allows for better testing and inspection, and I guess makes it marginally less likely that the main bonding conductors will be disturbed during add-n-move work in the CU/dis-board. One more practicality consideration is that the terminals on externally-mounted earth blocks (widely available in 5-way and 8-way sizes, from memory) is that each Hole is big enough for a 10mmsq conductor at least, more usually a 16mmsq (the outer ones at least are sized for 16mmsq+).

As for putting the main earthing terminal close to CU or close to incoming supply - I don't think there's an overriding argument (or reg) either way: practical factors such as proximity of the other services you're bonding to will usually make one or other preferred in those rarish cases where incoming supply and CU aren't within a couple of metres of each other...

Stefek

Reply to
Stefek Zaba

In message , Christian McArdle writes

He had one go a while back, but couldn't get them to talk any sense.

He explained (or tried to) what he was planning on doing, and any specific requirements etc. from them, but all the person he spoke to could do was witter on about getting an electrician in, that the electric's in the house were nothing to do with them. I don't think they really understood what he as talking about.

Reply to
chris French

See 542-04-02, I don't see this as in any way mandating an external terminal, though having one would often make this requirement easier to fulfil.

The biggest problem I have when doing this is the mandatory "Safety Electrical Connection" label - I'm probably missing a trick, but the only source of these I have at the moment is to nick them from pipe clamps which then leaves me with a pile of unuseable clamps.

Hwyl!

M.

Reply to
Martin Angove

You need to find out who the actual supplier is - i.e. the people responsible for the infrastructure in the area, not the people he pays the bill to. Around here (South Wales) it is Western Power Distribution and their number is in the phone book. In Derby it used to be East Midlands Electricity and their number is still in the phonebook (use the "new supplies" one) but the actual company involved is something else altogether now - a name I've forgotten.

Western Power will often provide a PME terminal for free, if the local supply is capable. The people who have just done this for me in Derby wanted forms filling in and a fee of £75.

I suppose what I'm saying is that it is a case of finding the right people to speak to.

HTH

Hwyl!

M.

Reply to
Martin Angove

I am about to replace my CU (well have been getting round to it for a few weeks now!) - if you have an earth block outside the CU does this effectively go between the incoming earth and the earth rail in the CU (i.e. wire main incomer -> earth block, earth block -> CU, earth block -> gas main, earth block -> water main etc)?

Reply to
a

Yes. All main equipotential bonding, incoming earths and the consumer unit earths are connected here. If doing the lot from scratch, ensure you install to TN-C-S (PME) specs, even if you don't have PME available. Otherwise, when the electricity company upgrades you, you're shafted.

Christian.

Reply to
Christian McArdle

In message , Martin Angove writes

Yep, we realised that- it'd Yorkshire Electricity (or whatever they are called now)

Yes, that's the conclusion we came too. I think the person he spoke to didn't quite understand what was being asked, and instead of admitting such and passing us on, tried to give an answer they thought was right

Reply to
chris French

I'm in exactly the same situation (in Leeds) - but am one step further on as I have installed the new CU and bonding etc.

I contacted British Gas (my electricity supplier) who - eventually - understood that I needed a proper earth system and agreed (verbally) that it was their responsibility and they would do it for free. At one point they even described it as "an electrical emergency" - which was putting it a little melodramatically.

Anyway, they sent someone out to sort it out (this was before I had the consumer unit and bonding done) and they looked at it and said "there's nothing I can do - there's nothing to attach the new earth to". Fair point, I suppose, as I hadn't got an earth block at that point and they weren't going to provide me with one. So I waited until I'd done it myself, and then got them back out again. (Incidentally, it's Meter Plus who they send to do their work).

This time, they said "can't do anything for you - you've got an old knockout [I think that's his terminology] and that needs replacing before I can do anything. Anyway, I wouldn't do it for my pay 'cause they expect you to work on the system live". Fair point again, but I still don't have an earth. He said he'd pass on the request for the new "knockout" to be installed, estimated 7-8 weeks. Then, he'll send someone else to do the earth.

So, it seems they will do it, but as for when, your guess is as good as mine.

Tom

Reply to
Tom W

I've always thought the label on an earth clamp rather strange - what other purpose would a clamp on a pipe with a cable coming from it serve?

Reply to
Dave Plowman (News)

"Tom W" wrote | I contacted British Gas (my electricity supplier) who - eventually - | understood that I needed a proper earth system and agreed (verbally) | that it was their responsibility

Which it isn't. The electricity supplier is not required to provide you with an earth

| This time, they said "can't do anything for you - you've got an old | knockout [I think that's his terminology]

Would that be a "cutout" (service fuse assembly)?

| and that needs replacing before I can do anything. Anyway, I wouldn't | do it for my pay 'cause they expect you to work on the system live". | Fair point again,

Well, if he doesn't like the job there's always McDonalds. And he shouldn't be live working unless he has been specifically trained.

Owain

Reply to
Owain

"Dave Plowman (News)" wrote | Martin Angove wrote: | > The biggest problem I have when doing this is the mandatory | > "Safety Electrical Connection" label - I'm probably missing | > a trick, but the only source of these I have at the moment | > is to nick them from pipe clamps which then leaves me with | > a pile of unuseable clamps.

Sell them on fetishgear.com as a form of body jewellery?

| I've always thought the label on an earth clamp rather strange | - what other purpose would a clamp on a pipe with a cable coming | from it serve?

Differentiate between safety electrical earth and a functional earth for telecomms or grandma's wireless?

Owain

Reply to
Owain

It's mandated by BS 951 which goes back to 1948, if not before. Plumbers in those days...

Reply to
Andy Wade

"Andy Wade" wrote | Dave Plowman (News) wrote: | > I've always thought the label on an earth clamp rather strange | > - what other purpose would a clamp on a pipe with a cable coming | > from it serve? | It's mandated by BS 951 which goes back to 1948, if not before.

Probably to indicate the (bare copper) earth wasn't anything to do with the wireless, then.

| Plumbers in those days...

Were plentiful, available, honest and cheap?

Owain

Reply to
Owain

In message , Christian McArdle writes

Oh go on, save me the effort of looking it up :-) what does that mean in practice?

Reply to
chris French

Using meaty earth cable. The OSG states the size of earthing conductors for each type of earthing. Always install those recommended for TN-C-S, whatever type of earthing you actually have.

Christian.

Reply to
Christian McArdle

This is certainly drifting off on a tangent, but I believe that East Midlands Electricity is now Powergen.

How do I know this?

Five-ish years ago I was working in Stafford, and East Midlands Electricity ran an advert on the TV to promote the change of name. I'll never forget that advert, it went something like this:

- Fade up to show a close-up of an old chap screwing in a light bulb.

- Zoom out to show him screwing in the next light bulb in a large grid; and the next bulb; and the next..

- Pan to show the sky in the background. The sky goes dark, then light, then dark, then light. A few days pass, and this poor chap still hasn't finished fitting these light bulbs.

- Finally there is a shot of the last light bulb to be fitted. The light bulbs are turned on and the chap leans back with a contented sigh.

- Zoom out to show his completed effort. It's a large matrix display of lamps on top of a large building (presumably their headquarters), and it reads "EAST MIDLANDS ELECTRICITY"

- Cut to voice-over and caption, saying: "East Midlands Electricity . . . is now changing its name to Powergen"

- Cut to old man, sighing, starting to unscrew all the light bulbs...! :-)

At the time I remember thinking it was a superb advert. I wonder if anybody has kept a copy on video somewhere? It surely deserves to be preserved for posterity!

Cheers,

Jonathan

Reply to
Jonathan

Nah, they're something else. One of those wishy-washy, doesn't-sound-like-an-electricity-company names. But when I looked it up in the phonebook it was there under EME.

Hwyl!

M.

Reply to
Martin Angove

In Derby I needed specifically to telephone the "New Supplies" number in the phonebook. Does YE have a similar number? If not, try bandying the phrases "PME", "TN-C-S" or "TN-S" around. Sometimes jargon like this rings a bell in what passes for the brain of the telephone answerer and causes them to remember some long-past training they undertook.

HTH.

Hwyl!

M.

Reply to
Martin Angove

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