Bathrooms and earth bonding

[Anon]

I'm shortly to refit our aged bathroom - and have just noticed that there is no earth bonding at present within the bathroom. There also doesn't seem to be any earth connection from any cold or hot water pipe back to the earth terminal by the consumer unit, although there is from the incoming gas pipe near the gas meter back to the earth terminal by the consumer unit. The property was built in the 1950's.

As I have to change round some of the pipework, would it be safer to put in a meter or so of plastic piping to the bath and basin, or continue to use metal pipes but bond them and the metal fixtures (bath, radiator, pipes) together ?

At present the bathroom has bath, basin, radiator, all connected with metal pipes (no bonding), and no other electrical appliances except for ceiling light with pull chord.

Having looked at the various previous discussions on the subject it looks rather confusing !

Any advice would be appreciated.

[Christian McArdle]

It is safer to use plastic and thus not require bonding.

Christian.

[Andy Wade]

Either, but you'd have to make virtually all the pipework in the room plastic in order to dispense with the supplementary bonding. Short copper tails to taps don't need bonding if the rest of the pipework is plastic.

Pull chord - very musical :-). Where are the light and switch in relation to the bath and how high above the floor?

Quite simple really: bond together with 4 mm^2 wire all the separate incoming metal pipes, the bath (if metal) and the electrical earths of any circuits supplying equipment in the defined Zones. Also bond any metal waste pipes. The radiator itself doesn't need bonding, only the metal pipework to it (unless it's fixed to a steel building structure - unlikely in this case).

The Zones end once you are 3 m away (horizontally) from the bath. Vertically the Zones stop at 3 m above the floor over and near the bath, but at 2.25 m above the floor once you're more than 0.6 m horizontally away from the bath. So the light circuit won't need bonding if it's more than 0.6 m away from the bath edge and higher than 2.25 m above floor level.

Bathroom supplementary bonding 'stands alone' and does not need to be connected to the main earth terminal (in or near the consumer unit). The rising water main (wherever located) should be bonded to the main earth terminal in 10 mm^2, just downstream of the main stop-c*ck (this is main bonding, like on the gas service).

HTH

[Andy Dingley]

Doesn't need it - it only needs equipotential bonding. It's much the same inside the room, but it doesn't have to be run back to an earth point.

Read your On-site Guide for details (if you haven't got one, buy one)

[EricP]

Are you lot sure about this?

I mean it is obviously a valuable opportunity to make the public do something absolutely pointless at serious cost, that has been missed!

There must be a Part P (Plastic) somewhere.

[Steve]

Is extra bonding i.e. parallel bonding connections (Belts and Braces) allowed by the regs?

Steve

[Andy Wade]

It's not disallowed. What did you have in mind?

[Anon]

Thanks for that Andy, the light switch is away from zone 1. I wonder how effective the earth bond is to the gas pipe - transco replaced the pipe from the meter with a plastic one last year !

[Steve]

Well, the bathroom which I did (pre part P) has all pipes bonded already but under the kitchen sink there is also bonding of the pipes and sink.

I am soon to fit a new kitchen and would want to continue with this arrangement, although as the plumbing is all copper it might not be strictly necessary. I can not see any problem with additional bonding, only advantage hence 'Belts and Braces' but knowing what regulations can be like, I thought that I might fall foul of some diktat that does not allow it ;-)

I think it is time for me to invest in an up to date book covering these sort of things. Any recommendations?

Steve.

[dcbwhaley]

A plastic pipe isn't an "extraneous metal part" and can't "introduce a potential" so the effectiveness of the bonding isn't relevent. Apart from bathrooms only metal pipes that leave the house need bonding.

[ARWadsworth]

4.3 Main Equipotential Bonding - Plastic services

There is no requirement to main bond an incoming service where both service pipe and the pipework within the installation are both of plastic. Where there is a plastic incoming service and a matal installaition within the premises, main bonding must be carried out, the bonding being applied on the customer's side of amy meter, main stop c*ck or insulating insert

As the gas pipework withing the house is metal then I would suggest main bonding is still required in this case.

Adam

[dan]

[dan]

[dan]

[Andy Wade]

Supplementary bonding in a kitchen isn't required at all, but it's certainly not forbidden. If the incoming water main rises in the kitchen, as they often do of course, then it needs main bonding to the main earth terminal (10 mm^2).

The IET On-Site Guide is the usual recommendation:

EGBR is also useful: