Earth bonding confusion

What is the rational behind earth bonding? Surely one bond to copper water pipes should be sufficient, after all copper and the water it contains are conductors.

I was befuddled by a comment on one of TV's home programmes. The presenter looked at the toilet and said, this will have to be bonded, there is a risk from the toilet flushing handle. Firstly how did he know that it was not bonded below the floor? Secondly my toilet flushing handles are plastic, and there is not metal in the flushing mechanism either. So where is the risk?

Cheers John T

Reply to
Broadback
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I saw the prog also and i suspect the presenter is misinformed. There were amendments to the reg a while back which made it a requirement to have additional earth bonding within wet areas eg bathroom. I dont think these regs were retrospective though!,i could be wrong..

Reply to
tarquinlinbin

Because he was being a smart alec - again.

As the house was quite old it probably had all copper pipes and was bonded at the water and earth entry point to the house. Only modern plastic plumbing needs wires everywhere and even these should be crimped and hidden under the floor to stop little fingers fiddling with them.

Reply to
G&M
O

So the presenter was fully qualified electrician ?

Dave

Reply to
Dave Stanton

Anyone see the TV prog when that Gavin installs the cross bonding under the boiler in the kitchen

Fixes the four or five clamps in place and the offers the earthwire up to the first clamp and cuts it!! bet the sparks that actually did the running of the cable winched, then as he links it to the next one he says or you can do it by stripping off the g/y insulation and just looping them together . little point after cutting the first

Steve

Reply to
Steve

Plastic piping is most unlkikely to have wires everywhere as a bathroom plumbed in plastic will not need supplementary bonding.

Adam

Reply to
ARWadsworth

Sorry to disagree but there was a debate here on this very subject and opinion was all metal items - taps, radiator and so on in a bathroom DID need bonding whereas in a kitchen they did not.

Reply to
G&M

Kitchens do not need supplementary bonding regardless of the type of pipe used in it's plumbing.

A bathroom that is piped in all plastic should not have its radiator bonded. This has been mentioned in many earlier threads here and is also stated in the IEE OSG and on NICEIC newsletters. Taps that are supplied by plastic pipes do not require bonding and taps that are supplied by copper piping are protected by bonding the copper pipe. I have never seen a 'bonded tap'.

Adam

Reply to
ARWadsworth

Agreed

Could whoever argued for this last time answer this ? You convinced me to do so last time. Thanks.

Some brands of tap come with a bonding tag. Whether this is required in the UK is another matter of course.

Reply to
G&M

Well I argued that you definitely should NOT bond radiators, metal baths, taps or metal window frames that would otherwise have no connection to earth.

These items should only be bonded if they are already earthed, such as through metal pipework or touching the structural metalwork of the building.

Christian.

Reply to
Christian McArdle

Not retrospective, but there are exceptions. I remember the programme; it was Location - L - L with two "first time buyers". I can't remember which one it was viewing that house, but if it was the lady from London, don't forget that she was viewing the house with respect to letting it out. If she does so then as landlord she will be responsible for the electrical installation and AIUI this means ensuring that it is compliant with the latest regulations.

If the viewers were the other two who were buying a house for themselves then it's a little more complicated. Although for a private dwelling the updates aren't retrospective, they could well have problems if their survey - needed for mortgage approval - comes up with too many notes on the electrical side saying things like "does not comply". It is possible (indeed probable) that an unenlightened mortgage company will see this and insist in work being carried out that isn't strictly necessary before releasing the full loan.

HTH.

Hwyl!

M.

Reply to
Martin Angove

Yes, this is specifically pointed out in the OSG - it makes it very clear that supplementary bonding of *isolated* metalwork is in fact more dangerous than leaving it isolated.

What I remember we argued about was the definition of isolated. A very short length of plastic pipe (less than about 1 meter) does not count as due to the conductivity of the water the metal item (tap, radiator etc) could still be said to be "earthy" and therefore should be bonded. Above 1m or so the resistance of the water becomes sufficiently high for the item in question to be regarded as isolated from earth.

This figure of 1 meter was IIRC calculated and reported in an IEE newsletter, and repeated fairly recently.

Hwyl!

M.

Reply to
Martin Angove

It wasn't so clear. It said that anything above 1m was safe, but didn't actually say that anything under 1m was not. They should, perhaps, have worded it more carefully, although this may have required further testing to determine a reasonable cut off point.

Also, there was nothing said about the effects of salts such as might be found in cleaning and beauty products when going down the drain.

Christian.

Reply to
Christian McArdle

I hadn't considered waste - waste pipe is rarely (never?) "filled" with water in the way that supply and heating pipe is, and the nature of the flow is intermittent to say the least. On top of that, waste has been

90% plastic for many years now, and the only metal waste you are likely to encounter is the odd cast-iron stack...

Contaminants in the supply water are another matter - treatments in the heating water, salts in softened water and so on. Hmmm :-/

Hwyl!

M.

Reply to
Martin Angove

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