Protective Equipotential Bonding

[securespark]

Q for the sparks here:

If you find a copper water pipe with several plastic joints in it (or bends as I found today) what advice would you give regarding the need for a PEB connection to that pipe?

 

[ricicle]

If the pipe is metallic coming in from the outside (introduction of earth from outside the equipotential zone) then bond as normal, even if it becomes plastic in the building. If totally plastic then not much point in bonding.

The whole point of bonding to water, gas etc is as said above to prevent the introduction of other earth potentials from outside the equipotential zone!

 

[SgtTrojan]

For a service pipe, the main bonding conductor should be connected as near as possible to the point where the service enters the building. The connection must be before any branched pipework and on the consumers side of any meter. If possible the connection should be made within 600mm of the meter outlet. Where the meter is outside, the bonding connection should be made at the point of entry of the service into the building. 544.1.2

 

[securespark]

OK, rice. I agree with you that metallic pipes coming in need bonding even if they then subsequently change to plastic, but what niggles me are the "hybrid" systems:

What about a poly pipe coming into the property that changes to copper post-stopcock, but that continuity via the copper pipe is then broken in several places by plastic elbows??

Isn't the reason for bonding potentially two-fold?

To protect against an earth potential introduced from outside the EZ & also to protect the pipework inside the EZ?

Obviously, there is no continuity in a metallic pipe system if plastic joints are used.

 

[Spark123]

I know what you mean - they are complete lash ups and the installers should be punished severely!!
If it is copper directly post stop tap where it enters then I'd say bond there. It is there to stop any potential differences being introduced from outside the premises. The placcy joints etc might cause issues with the effectiveness of the resistance readings from the pipework in a bathroom to the MET hence supplementary bonding required.
If it is plastic directly post stop tap for an adequate distance to provide isolation i.e. you can measure more 22k ohms between the metalic pipework and the MET then it isn't deemed to be an extraneous conductive part and doesn't require bonding.

 

[securespark]

That's really helped clarify it in my mind - thanks!