Earth Bonding Pipes Under Sink?

[ScubaCollie]

Morning All, we moved into a newish house nearly two years ago, built approximately 12 years ago, in Scotland, timber framed, with plastic piping, apart from near boiler, and under kitchen sink etc, and possibly other sinks (I haven't checked yet as all the other are all wall mounted and concealed by the ceramic underparts of the basins).

Anyway getting back to the kitchen sink, removed the stainless steel one, fitted a new Composite type, and new taps, had to remove the earth Bonding to undo and redo the copper fittings on the pipes.

Question Is: why is the approx 12" of copper pipe under sink earth bonded (only to each other I. E clamp around cold, earth lead running to hot with another clamp mounted to the hot) and not then going anywhere else?

The copper pipe run (approx 12") then goes into plastic piping apprix 12" above the sink unit and dissapears under the floor.....

Anybody got any ideas? It's simple to reattach it I'm just curious why it's been done as surely needs to go back to earth along copper pipe then either to an earth rod or the consumer unit?

 

[Madrab]

It all comes down to earthing exposed metal pipework/sinks/baths/etc. If for any reason a metal pipe/surface became electrified then the bonding can hep in equalising/reducing the voltage hopefully minimising the risk of it killing someone. As a lot of the pipe is plastic then there is now no natural path to earth therefore equipotential (earth) bonding is fitted to any exposed metalwork.

Basically it's a safety thing

https://www.safeopedia.com/definition/5577/equipotential-bonding

 

[ScubaCollie]

It all comes down to earthing exposed metal pipework/sinks/baths/etc. If for any reason a metal pipe/surface became electrified then the bonding can hep in equalising/reducing the voltage hopefully minimising the risk of it killing someone. As a lot of the pipe is plastic then there is now no natural path to earth therefore equipotential (earth) bonding is fitted to any exposed metalwork.

Basically it's a safety thing

https://www.safeopedia.com/definition/5577/equipotential-bonding

Many Thanks mate. So therefore even though there's no run back to an Earth rod or the consumer unit, by linking the two copper pipes together, kind of equalises the pipes and therefore would either stop or reduce the amount of current flow from one pipe, through the human body, and to the other pipe? Whereas if they weren't connected/equalised, the current would flow rapidly from the higher current pipe through the body and to the lower current pipe?

 

[denso13]

by linking the two copper pipes together,

It's bonding not earthing and hard to say if you still need it. Is the system all copper or this any plastic pipework upstream of the sink pipework? If so bonding isn't required.

 

[ScubaCollie]

It's bonding not earthing and hard to say if you still need it. Is the system all copper or this any plastic pipework upstream of the sink pipework? If so bonding isn't required.

Hi mate the plastic pipe comes out of the floor, into cabinet, up to approx 12' below sink, connects to copper pipework for approx 12 ' then connects to a flexi pipe then the taps?

 

[denso13]

Hi mate the plastic pipe comes out of the floor, into cabinet, up to approx 12' below sink, connects to copper pipework for approx 12 ' then connects to a flexi pipe then the taps?

No need for bonding.