Equipotential bonding Help

[easysushi]

Gents,

I have replaced a consumer unit for a friend, however my pre works survey pickup that there was not Equipotential bonding on any radiators and that there was no path back to earth. I assumed that the piping was in plastic but wanted to confirm with my friend, he confirm that the boiler was renewed about 5 years ago and some of the system was in plastic and that it went back in to copper and that we could resolve the next day by lifting the boards on the. I fitted the consumer unit, the next day we took up some floor boards and discovered that the main flow/return from the boiler is 22mm plastic spurring off way under the floor boards then back in to copper upstairs and downstairs. A continuity check confirmed that the upstairs rads are all linked via flow/return and the downstairs rads are all linked via flow/return

Why question is how doI resolve this without ripping up all the boards and bonding pipes together, or am I looking at his the wrong way.


Any help very much appreciated


Cheers


Easysushi

 

[sparkylad]

I take it as you are referring to Main Equip Bonding. This goes to any extraneous conductive parts entering the building. You can check if the part is extraneous or not by testing back to the MET----If greater than 2200 ohms then dont bond

 

[Spudnik]

As above, plus its also not needed if all circuits in the CU have 30mA RCD protection.

 

[easysushi]

As above, plus its also not needed if all circuits in the CU have 30mA RCD protection.

Thanks Mate, any idea where that is in the regs. All circuits installed are RCD protected.


Ty

 

[sparkylad]

As above, plus its also not needed if all circuits in the CU have 30mA RCD protection.

Hi Jason. am still not sure if the OP is referring to Main or to Supplementary Bonding----your advice obviously refers to Supplementary and not Main-perhaps the OP can assist

 

[Deleted member 9648]

The heating system rarely requires main bonding.
An extraneous conductive part is defined as a metallic service entering the building LIABLE TO INTRODUCE A POTENTIAL,GENERALLY EARTH....This explains why main bonding is carried out at the point of entry of the service as the earth potential is coming from outside,once within the confines of the building metallic pipes can no longer gain an outside earth potential so there can be as many plastic inserts as you like,the hazard has been dealt with by bonding at the point of entry.(Where plastic services enter they may still introduce an earth potential through water etc and should be main bonded at the first available metallic section)
A heating system is generally wholly within the confines of the building apart from the flue vent on a wall...therefore it cannot introduce an eath potential and will not require main bonding. An exception is a boiler located externally with the flow and return coming into the house from outside,as stated in the previous post you can test to see if the pipes are extraneous conductive parts but in these circumstances I would always main bond at the point of entry.
Supplementary bonding is slightly different and is only required in special locations...ie in a normal domestic the bath and shower rooms. Due to the increased shock risk in these locations metallic pipes entering the special locations are treated as extraneous conductive parts,and a bond is made between conductive parts(earthed electrical parts) and the metallic services where they enter the special location.Once within the special location it matters not again how many plastic insert are fitted to the pipes as the hazard is comming from outside the special location and is dealt with by bonding at the point of entry.
The 17th edition allowed supplementary bonding to be omitted provided
1,All circuits within the special location are 30ma rcd protected
2,The required disconnection times are met for all circuits within the special location
3,A continuity reading of <1667 ohms is obtained between conductive and extraneous conductive parts within the special location.
Nothing else is required...there is no need for continuity through all the plumbing in the house,no need for "cross bonding" at boilers and kitchen sinks......understand the principles and reasons for bonding and you will see why.

 

[easysushi]

Hi Jason. am still not sure if the OP is referring to Main or to Supplementary Bonding----your advice obviously refers to Supplementary and not Main-perhaps the OP can assist

Gents, I'm refering to supplementary, not main


Cheers


Ty

 

[sparkylad]

TY . Wirepuller states it all nicely above