earthing

[Odd Job]

Hiya while i have the floor boards up i thought i would check here regarding earthing.

I found the attachments to water pipes under the sink in bathroom and one goes off behind the bath, which i will check when i get started, but... the sink one is not tightened up and is hanging free.

im Gathering this is a big no no!!! so i would like to redo the earthing if possible and if acceptable just tighten whats there the wire is green and yellow and looks quite new although last rewire was 18 years ago.

Ive had a read in wiki but still a bit unsure as no diagram that brings it home.


So im lost as to how many earths you end up with to the consumer unit.
do all pipe fittings get wired and then join up together to leave one wire as there is no way 5 or 6 wires will fit down conduit to enter back of consumer unit?

i have been advised that each pipe from teh boiler can go to each other but im not sure where from there.

Also please would i need to earth a stainless steel sink direct to the sink or on the water pipe to taps, so using access from bathroom area.

thanks OJ

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[davy_owen_88]

You should have main bonding to gas/oil/water pipes and structural metalwork at the point which they enter the building. You should use 10mm² and they should be a single unbroken length back to the CU. You can use a different length for each service or you can loop a single piece between them (but it can not be cut).

You do not main bond boiler pipes. Cross bonding between them is fine (use 4mm²), but don't take it back to the consumer unit.

In the bathroom all metal parts (pipes, radiators etc) should be bonded together and then to the CPC of every circuit entering the bathroom using 4mm² cable. Pipes can act as bonding conductors as can the CPC of the circuits you are bonding. All connections must be accessible (not under the floorboards).

If you bond the pipes you don't have to bond the taps, if you bond the pipe feeding the radiator you don't have to bond the actual radiator. If there are metal taps, radiators, etc fed by plastic pipes they do not need bonding. Don't bond plastic pipes atall.

Supplementary bonding is not carried out in kitchens.

 

[Odd Job]

Thanks Davey, im getting the picture now can i ask a bit more please?

The main supply earths will be a seperate 10 mm loop going to each incoming main pipe after the meters and connected to the CU?

So this mains water pipe earthing does not have to be part of the bathroom and kitchen connections. If so These are all in one cupboard and i will leave this to the electrician this wkend.

The bathroom and kitchen are 2 new CU connections.?

but

Can i make the bathroom and kitchen all run on 1 CU connection. Copper pipes run directly down for kitchen sink. i could pass the wire down through existing trunking


im going to have to post 2nd half of message below for some reason i cant do a long post

 

[Odd Job]

Also can i use a the 10mm all the way through so as not to have broken connections anywhere or is this a must for 4mm between pipes . ( cost wise it won't make much difference i can wash me hands, sit on the loo and bath me feet all at the same time )

regarding the boiler i have been advised as i have a baxi bermuda the mains supply on the control unit does the earthing? im not sure im comfortable with this something doesnt add up? surely all my radiator pipes from the boiler can't be earthed by that can they? could you advise please.

thanks
OJ

 

[davy_owen_88]

The main supply earths will be a seperate 10 mm loop going to each incoming main pipe after the meters and connected to the CU?

Yes.

So this mains water pipe earthing does not have to be part of the bathroom and kitchen connections. If so These are all in one cupboard and i will leave this to the electrician this wkend.

Indeed. Main bonding is separate to supplementary bonding. They do not combine.

The bathroom and kitchen are 2 new CU connections.?

but

Can i make the bathroom and kitchen all run on 1 CU connection. Copper pipes run directly down for kitchen sink. i could pass the wire down through existing trunking

Supplementary bonding does not go back the the consumer unit and supplementary bonding is not carried out in the kitchen atall. The only CU connections for the kitchen/bathroom will that of the protective conductors of circuits within them.

Also can i use a the 10mm all the way through so as not to have broken connections anywhere or is this a must for 4mm between pipes . ( cost wise it won't make much difference i can wash me hands, sit on the loo and bath me feet all at the same time )

There is no need to use more than 4mm² cable for supp. bonding. The fewer joints the better.

regarding the boiler i have been advised as i have a baxi bermuda the mains supply on the control unit does the earthing? im not sure im comfortable with this something doesnt add up? surely all my radiator pipes from the boiler can't be earthed by that can they? could you advise please.

Your radiators don't need earthing/bonding, cross bonding the pipes is not a requirement to BS7671 but some plumbers do it for their own reasons and maybe it is a gas regulation. It is possible that inside the boiler there are connections between pipes so cross bonding is not necessary,

 

[Odd Job]

[Supplementary bonding does not go back the the consumer unit and supplementary bonding is not carried out in the kitchen atall. The only CU connections for the kitchen/bathroom will that of the protective conductors of circuits within them.,

thanks for that.

The earth fitted now actually goes back to the consumer unit down through the pipes..

Is it possible this is connected in to a ring at the back of the CU and not connected directly to the CU?

So to be safe and gain a supply to the new earth I can connect it up into a socket in the back bedroom or lower floor light ring if this is acceptable.