earth bonding on push fit plumbing fittings. Please help.

[owlhayden]

Hi, I can't find a decent answer to this anywhere. If the copper pipes in a bathroom are altered and now include push-fit elbows + tee's etc, to me this breaks the continuity bonding. I heard that these fittings should be bridged with green/yellow earth wire. The question i have is that why do I never see this bridging on push fit (plastic) braided(metal) hose tap connectors?

Perhaps, is this in case there is a non-visable break in the pipework further away and the plastic push fit connector on the braided tap connector would stop the taps becoming live? But then is there a risk that the braided hose would not be bonded. Like I say, I've never seen pushfit braided tap connectors under baths bridged with bonding. Maybe the connectors would crush the rubber pipe inside? Or there should be no stray current under the bath anyway? In this case it's a metal bath that is earthed
Sorry, I've tried to make it as clear as I can, hope it makes sense. Please help because this earthbonding stuff drives me crazy!

 

[ericmark]

Extraneous-conductive-parts (pipes) can transfer voltages of different potential into the same area. To prevent danger there are two methods either connect all exposed parts together or to install a RCD which will disconnect the supply should a fault to earth accrue.

If the house is wired to BS7671:2008 then the RCD method is used and there is no problem with plastic pipes or connectors.

Before BS7671:2008 RCD's were not required for bathroom items and all extraneous-conductive-parts were bonded together.

However the idea of bonding metal door handles is silly and really one is only looking at items which can connect different parts of the building electrical together i.e. pipes. Plastic pipes are not a problem and where metal pipes are only used in visible areas the short lengths of metal do not need bonding. Even as little as 1 meter of plastic pipe will isolate and where there is a mixture bonding is often not required.

But looking at push on elbows on metal pipe the length of water is unlikely to be sufficient so either it needs isolating by using some plastic pipe or bonding or use RCD to BS7671:2008.

Because there are three options it will be hard to find a single answer. I have found nothing in the regulations which gives the length of plastic pipe and diameter which is considered as isolation and impurities in the water would alter this anyway.

 

[electronicsuk]

As Eric already mentioned, we bond extraneous conductive parts (such as incoming water or gas supply pipes coming into the house) to prevent any outside electrical potential being introduced into the property, although in some cases we also supplementary bond exposed conductive parts.

In a domestic situation, supplementary bonding was and still is in some cases used to bond together multiple metallic services entering certain special locations, such as a bathroom, to ensure that no electrical potential exists between simultaneously accessible metallic parts.

I can't see how the use of plastic fittings will cause a problem in this case. Either you will deem that no bonding is required if the necessary conditions in the 17th edition are met, or you decide that bonding is required, in which case the bonding connections should all be accessible and likely near the conductive part being bonded.

Therefore, as the majority of your pushfit connections and pipework are going to be under the floor, they wouldn't need bonding anyway. The idea is that only exposed parts are bonded, and as far as I'm aware, there is no particular regulation that states that electrical continuity should be maintained throughout all metal pipework in a dwelling.

 

[Spark123]

Are we talking copper push fit or plastic push fit?
Short breaks in the copper may not provide adequate isolation hence the downstream copper will still be extraneous but not effectively connected to the protective bonding hence supplementary bonding may be needed.
I'd hope that metal push fits will provide continuity, only way really is to test it.