The incoming main has been changed to plastic, there is as section of copper that connects to that which supplies the kitchen, then it changes to plastic when it enters the bathroom. Is it pointless to put an earth clamp onto the copper and run a cable back to the MET?
Earthing a water pipe??
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Pointless. Also dangerous as it makes something part of the electrical installation when it wasn't before.
Don't do it.
Don't do it.
On Site Guide page 45 section 4.5"Where there is a plastic incoming service and a metal installation within the premises main bonding is recommended unless it is confirmed that any metallic pipework within the building is not introducing earth potential.
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So do you also apply main bonding to toothbrush racks, door handles, metal cabinets?
Well considering these items are unlikely to have a live cable near them it would seem somewhat pointless. That said I don't make the rules or form the guidance that in this thread you appear to disregard yet in another you seem very keen on. Perhaps you could get in contact with the IET and help them with the 18th Edition of the OSG, I am sure they will be very concerned that their recommendations are "dangerous".
Your terminology is incorrect and confusing you.
The conductor connected to incoming metal pipes etc. is NOT earthing; it is bonding.
Pipes etc. are required to be bonded because they are earthed - by the ground.
Bonding is nothing to do with the proximity of live cables.
They don't seem to be (concerned).
Consider 544.1.2 where it is stated that bonding be applied to the consumer's side of insulating sections.
Thus bonding that which does not require it and leaving unbonded that which does.
- They could easily have live cables very near them.
- How do you know that the bit of copper pipe in the kitchen does?
- It's irrelevant anyway.
Perhaps you should read the disclaimer at the front.
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It's not how close they are to live cables, it's whether they can introduce a potential (eg local earth) to the equipotential zone (ie the house)
If they can, it's a danger as all metal work needs to be the same potential. If not then it's just the same as anything else and floating is better than earthed.
If they can, it's a danger as all metal work needs to be the same potential. If not then it's just the same as anything else and floating is better than earthed.
In my opinion, that's a pretty daft statement. For a start, it should say "introducing earth potential from outside of the premises" (metal pipework of an installation is almost invariably connected to the installation's earth, via boilers, CH control valves, immersion heaters, etc. etc.). Secondly, whilst I agree that any conductor which could introduce true earth potential from outside of the the building needs main bonding, how on earth is metal pipework totally contained within the building going to do that (unless it dives down below a solid floor and has a stretch going through the ground beneath!)?
Kind Regards, John
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Indeed metal entirely within the equipotential zone can't but even if pipes could go under ground of course that's why you can prove it by testing the resistance from the main earth terminal to the part in question.
Interestingly I recall a document suggesting placing an earthed grid under ground floor wet room shower areas in pme installs as the floor could be an extraneous conductive part in effect, so needed bonding.
Interestingly I recall a document suggesting placing an earthed grid under ground floor wet room shower areas in pme installs as the floor could be an extraneous conductive part in effect, so needed bonding.
True, but only if one disconnected the installation from the MET or dismantled a fair bit of the plumbing, since, as I said, internal metal pipework is almost invariably connected to the MET via CPCs.
Indeed. We've quite often discussed this and I think there is no doubt that, in some situations, a solid floor (particularly of an outhouse) can qualify as an extraneous-c-p (hence needing bonding - and I think that a grid/mesh, or similar, is about the only way to do it).
Kind Regards, John
Thanks lads for all your answers, sadly some seem to say do it and some don't do it. Here's a thought..............the plastic and metal pipes are surely connected by the conductive water within the pipe which will create conductivity from the metal main in the road right up to the metal tap at the sink thereby making all the metal pipes and taps earthed..........or am I wrong?
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