Bathroom Bonding ?

Golden_Boy · Feb 13, 2010

I have a plumber ( well he calls himself a plumber ) in at the moment re-doing my bathroom, It involves moving bath, bog and washbasin to slightly different positions in the room. I have just spent a small fortune getting the electrics up to scratch and now the idiot had used plastic couplers all over the place so that the pipework is no longer electrically connected to the Earth terminal ( via the water pipe bonding ) as it was before. Should I have the copper pipes bonded back togetherto be on the safe side?

uksel · Feb 14, 2010

you say, 'not electrically connected to earth'.

have you proved this with a meter?

measured the resistance between exposed conductive parts? looking for no more than 0.05ohms

regs state that if there is no electrical connection to earth, they must be bonded

Deleted member 9648 · Feb 14, 2010

Only metallic pipework entering the bathroom may need to be supplementary bonded ,as close as possible to where it enters.It matters not whether there is continuity on the pipework once within the bathroom.If plastic pipework coming into the bathroom goes to copper there is no need to bond.
There is no need to supplementary bond if all circuits within the bathroom are RCD protected,and there is continuity of less than 1667 ohms between metallic pipework entering the bathroom and conductive (earthed) parts within the bathroom.

There seems to be this misunderstanding coming up regularly that bonding is to earth the pipes...IT IS NOT.
Bonding is to reduce the risk of a potential difference between metallic sevices entering a building or in this case bathroom, which may introduce an earth potential,and conductive parts connected to the earthing system. The risk of introducing an earth potential comes from OUTSIDE THE BUILDING/BATHROOM,that is why bonding must be carried out as close as possible to the point of entry. Once inside the building/bathroom the pipework is not going to introduce outside earth potential so it can have as many plastic fittings on it as you like.
Perhaps you owe your plumber an apology.

uksel · Feb 14, 2010

wirepuller said:
Only metallic pipework entering the bathroom may need to be supplementary bonded ,as close as possible to where it enters.It matters not whether there is continuity on the pipework once within the bathroom.If plastic pipework coming into the bathroom goes to copper there is no need to bond.
There is no need to supplementary bond if all circuits within the bathroom are RCD protected,and there is continuity of less than 1667 ohms between metallic pipework entering the bathroom and conductive (earthed) parts within the bathroom.

There seems to be this misunderstanding coming up regularly that bonding is to earth the pipes...IT IS NOT.
Bonding is to reduce the risk of a potential difference between metallic sevices entering a building or in this case bathroom, which may introduce an earth potential,and conductive parts connected to the earthing system. The risk of introducing an earth potential comes from OUTSIDE THE BUILDING/BATHROOM,that is why bonding must be carried out as close as possible to the point of entry. Once inside the building/bathroom the pipework is not going to introduce outside earth potential so it can have as many plastic fittings on it as you like.
Perhaps you owe your plumber an apology.

the point of the 0.05 ohm reading is for potential difference.

there are 3 requirements that need to be met to omit the use of supplementary bonding.

the 1667 ohms you refer to is the max tabulated Zs and not the resistance between metallic pipework

this again should be no greater than 0.05 ohms!!!!

think you may need to refer to the BRB p.166

p.s. a copper pipe connected after plastic piping would still be classified as an extraneous conductive part

vote of 1 for bonding

Deleted member 9648 · Feb 14, 2010

uksel said:
the point of the 0.05 ohm reading is for potential difference.

there are 3 requirements that need to be met to omit the use of supplementary bonding.

the 1667 ohms you refer to is the max tabulated Zs and not the resistance between metallic pipework

this again should be no greater than 0.05 ohms!!!!

think you may need to refer to the BRB p.166

p.s. a copper pipe connected after plastic piping would still be classified as an extraneous conductive part

vote of 1 for bonding

The BRB p166 refers to reg 415.2.2 which states the effectiveness of connection of extrananeous conductive parts to the MET for the purpose of supplementary bonding may be assessed by R<or equal to50v/Ra....where Ra is a 30ma RCD do the calculation and you will get 1667 ohms,dont know where you are getting 0.05ohms but it is wrong.

You need to look up the definition of an Extranuous conductive part in the BRB....'A conductive part liable to introduce a potential,generally earth and not forming part of the electrical installation'

The point is the introduction of an earth potential comes from outside the bathroom,once the metallic services are in the bathroom they can no longer introduce an outside earth potential,therefore supplementary bond is at the point of entry unless the three conditions to omit are met.

Copper pipe after plastic pipe within the room is not an extranuous conductive part....refer again to the definition of an extranuous conductive part.Also refer to P31-4.7 of the OSG regarding supplementary bonding of metallic pipes supplied by plastic pipes .

Golden_Boy · Feb 14, 2010

So I dont have to bother getting it done then?
BTW its a whilpool bath, does that make a diffrence?

Deleted member 9648 · Feb 14, 2010

If all circuits within the bathroom are protected by an RCD,the requirements for disconnection times are met,and you have a continuity reading of less than 1667 ohms between the MET and metallic pipework where it enters the bathroom you dont have to supplementary bond. Otherwise bond between any eathed parts in the bathroom,ie electric shower...light fitting etc and metallic pipes where they enter the bathroom. The regs allow you to use a metallic pipe as a suppllementary bonding conductor providing it is electrically continuous which often means bonding can carried out in a convenient location such as an airing cupboard...provided mettalic pipes are continuous untill they are in the bathroom,it doesnt matter if they are broken by plastic inserts after that.

Golden_Boy · Feb 14, 2010

wirepuller said:
If all circuits within the bathroom are protected by an RCD,the requirements for disconnection times are met,and you have a continuity reading of less than 1667 ohms between the MET and metallic pipework where it enters the bathroom you dont have to supplementary bond. Otherwise bond between any eathed parts in the bathroom,ie electric shower...light fitting etc and metallic pipes where they enter the bathroom. The regs allow you to use a metallic pipe as a suppllementary bonding conductor providing it is electrically continuous which often means bonding can carried out in a convenient location such as an airing cupboard...provided mettalic pipes are continuous untill they are in the bathroom,it doesnt matter if they are broken by plastic inserts after that.

Thats great... thank you...I have RCBO's type"32b" on the ring and type "6c" on the lights.

Golden_Boy · Feb 16, 2010

uksel said:
you say, 'not electrically connected to earth'.

have you proved this with a meter?

measured the resistance between exposed conductive parts? looking for no more than 0.05ohms

regs state that if there is no electrical connection to earth, they must be bonded

Just a final word... As I didnt answer the question asked re meter.
Yes I do own equipment to measure continuity and do know how to use it...
Its just the finer points of the regs that I am not familiar with.

I have worked in the electronics industry since 1966 so I think I know how to use a meter. Unlike some of the folk on here,who, even though "qualified", havn't got a clue !!!!!!!!!!