Earthing and bonding

4 Aug 2006
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United Kingdom
Having read hundreds of posts on bonding and earthing can someone just tell me if I have grasped this one....................! Nearing the end of new bathroom installation and got to thinking, none of these pipes have any earth wires on them?

Therefore should I

1. Run a 6mm green/yellow from the earth at the CU to the bathroom and clip to every pipe in turn.

2. Then bond all these pipes with more 6mm cable, if so, where would I pick up the earth feed?

Can anyone shed some light please.

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Bathroom bonding is done local at the bathroom, there is no need for it to connect to the MET (unless the water main or other metallic service therefore MAIN equipotential bonding is required.) Supplementary bonding is required to connect together all metal pipes such as central heating, hot/cold water, metallic building structure together with the earth conductor of any circuit supplying class 1 or 2 equipment in the zones of the bathroom, i.e. lighting circuit, electric shower etc. 4mm is adequate providing the earth wire for an electric shower isn't greater than 4mm.
Thanks Spark

Plain english. Is supplementry bonding the answer to my question 2? If so, providing the shower earth is 4mm can this bonding earth be taken from a lighting feed?
are you saying I don't need to connect an earth from the mains earth to bathroom pipes.
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4mm for bonding will be fine. I take it the shower cable was installed by a pro, kept away from insulation etc?
Where would I take the bonding earth feed from the light or shower? And would that be it no earthing from the mains required?
You need to bond together the earth of shower cable, the earth in the lighting circuit and all the pipes in 4mm cable. The earths still require to be connected at the CU and shower/light ends, attach the bond to the earth conductor at the bathroom end but don't disconnect them. You can use metallic pipework (providing it is electrically continuous) instead of cable as shown in the picture in the link I put in above. The idea behind supplementary bonding is to ensure all metalic parts which can introduce a potential in a bathroom are at (or very close to) the same potential, hence the increased risk of electrocution is owing to being wet/unclothed is reduced.

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