It is not possible to earth plastic piping as plastic is an insulator.
You can only earth conductors of electricity - mainly metals.
Your main fuseboard should have an earth connection to the incomming water main, assuming that this is made of metal. New water pipes are blue and made of polypropolene, so cannot be earthed either.
The water in the pipework is also a conductor, so as long as there is water in the mains supply pipes, and this water flows through a metal pipe that is earthed then a theoretical earth exists. However, this may be of poor quality, and is unpredictable, as the water board can fit new poly pipe at any time.
Earthing through water would not be acceptable to the Electrical regulations.
The purpose of EB is to protect against indirect contact with electricity and to automatically disconnect the supply IAW the requirements of the Wiring Regulations (BS 7671:2001) and to stop the Leo Sayer look!
Metal pipework can provide a route for stray electric current to go to earth. This could cause an electric shock for someone touching the â€˜liveâ€™ pipework unless the metal is properly earthed. It can also cause the pipework to corrode.
Therefore, â€œIf you use plastic piping, do you need to earth the piping at some point?â€
Depends on whether you are connecting plastic to existing copper, back to copper; in which case you need to put a 'jumper' earth wire (4mm min) between the two copper pipes.
However if your installation is completly plastic you don't need any supplementary bonding because what are you earthing to?
If your connecting to the existing copper heating then yes you definitly require an earth to the rad especially if you use platic pipes between as whomever touches the radiator when a fault is present (say pump live going to casing) & the earthing to your house isn't up to scratch, then that person potentially becomes the earth point for the radiator/house! Bzzzt!!
But If all pipework is plastic then as water has a resistance & the longer the run then the higher the resistance which reduces the voltage potential so negating the need for earthing any metalwork such as taps etc (impractical to do so anyway; I know I wouldn't want an earth tag & wire wraped around my franke's!! haha).
Your electrician should be able to advise you fully, he was probably talking about an RCD (residual current device) the newly released 17th edition regulations have an ever increasing requirment for these.
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