bonding

[frenchy]

hi could someone please help i have a re-wire to do incoming water is copper but from the stopcock it changes to plastic the plumber is going to use copper for the drops from the bolier rads and taps would these still need to be cross bonded i think not but not come across this before so would like some help please many thanks


frenchy

 

[xraytek]

Hmmm quite a few page views but no replies yet so I shall see if I can draw the lions out of the long grass

Firstly you say the pipework is plastic immeadiately after the stopcock, but for what distance?

If most of the water system is copperl but with a little plastic at the incoming my suggestion would be to have a short length of copper fitted at the stopcock for fitting the bonding clamp.

 

[Victor]

I am confused!!!!!!!

If you have a copper incoming pipe which then runs into plastic and then back to copper, should you not bond all of the copper pipes and not just the incoming as plastic is not a conductor?

 

[Sintra]

hi could someone please help i have a re-wire to do incoming water is copper but from the stopcock it changes to plastic the plumber is going to use copper for the drops from the bolier rads and taps would these still need to be cross bonded i think not but no come across this before so would like some help please many thanks


frenchy

It is not generally required to supplementary bond the following :kitchen pipes, sinks, draining boards, metallic kitchen furniture, boiler pipes, metallic parts supplied by plastic pipes or metal pipes to hand basins or wc's ( excluding metal waste pipes in contact with earth ). OSG p31

 

[frenchy]

thanks there is a small length of copper after the stop cock for me to do the meb but i'm thinking more about seb of the bath room and kitchen and boiler

 

[calv68]

what you have to take into account is that electricity travells with water, so if i follow a plumber whos just done a kitchen with plastic i allways crossbond.

 

[parkerbloggs]

get your R2 lead out and measure res between met and any suspect extraneous conductive parts. anything above 25Kohm is ok.

 

[Davey101]

I have similar in my house. From the new boiler approx 15 metres of new plastic which then joins to the existing copper under floorboards and the drops. I ran a 4mm to the copper and cross bonded. I agree that you do not need to bond small sections i.e. radiator/ tap connections.. There is a reg that states that heating pipework shall be bonded to the main earth terminal (cant remember the reg no though), but as Sintra said, supplementary bonding isnt necessarily required. I think if the majority of the central heating pipework is in copper, this should be bonded, if it is just drops out of the ceiling to the rads, then I presume you dont need to.

metallic kitchen furniture. OSG p31

I notice this in the OSG. Its always been my understanding that any metal kitchen tables that are likely to have electrical kit placed on them ( mixers, mincers and the like), or if they are adjecent to electrical appliances (dishwashers, ovens etc), then they should be earthed. We were actually advised of this on an NICEIC inspection. Is there a reg that clears this up better than the OSG?

 

[Deleted member 9648]

I think there is some confusion on this as it seems many people believe the purpose of main bonding is to earth the pipework and thus a plastic insert will leave copper pipework beyond that point unearthed. The purpose of main bonding is to ensure that there can be no potential difference between conductive parts of the installation connected to the earthing system and incoming services intoducing an earth potential from outside of the building. Therefore in the case of a plastic pipe coming from the stopcock main bonding should be at the first available section of copper....the pipework beyond this point matters not as once within the building it cannot introduce an external earth potential. Only in special locations might any further supplementary bonding be required.

 

[Davey101]

So if the mains water supply is in plastic, you dont need to earth your copper pipework in your building?