New CU, but bonding not 10mm2. What to do??

[malcolmsanford]

What you got to remember that Reg 544.1.2 states shall be made as near as practicable to the point of entry. That 600mm also where as practicable, it then goes on to say that the only certain thing is it must be made before any branchwork. So in theory 600mm is best, in the real world bond in the best position before a branch, so if that is 3 meters then 3 metres it is, just do it before any branch.

Now the bonding to that flat must be done in the flat, so forget the cellar. You will most likely find that it it may be 6mm where you can see it but it may have a joint and a length of 1mm inserted. I personally have seen this a 6mm cable from the gas pipe entry in the kitchen and when it went under the floorboards there was a connector block and a 7metre run of 1mm^ to another connector block and then 6mm again to the MET.

Now the bonding for a TN-S clearly states in reg 544.1.1 that it must be no less than half the CSA of the protective conductor. The protective condutor for the installation is either worked out by reg 543.1.3 or by table 54.7. If you have worked out that your protective conductor can be 10mm^ then you can use a 6mm^ as per reg 544.1.1, but you have to be able to prove this with your calcualtions if ever anything went wrong

 

[Ampere]

Did you null meter before testing using a long lead from main earth to gas and water? sounds like readings obtained included the wander lead.

 

[Jimmy Boy]

The resistance of the lead should be stamped on the wander lead if you can't null it