Supplemental bonding

[nozspark]

If you were doing a CU change and there was no obvious supplemental bonding, but HOT-COLD-RAD were all below 0.05 ohms, would you still bond everything or would you just bond the lighting to the pipe work??

 

[equitum]

Depends on what was agreed with the customer on the quotation/what the customer is willing to pay for.

 

[equitum]

Having thought some more about your post, the actual resistance between the pipes is irrelevent. Supplementary bonding has to be local, i.e in the room or in an adjacent area. The connectivity in your instance is probably due to connections at the boiler, in an all copper installation. If the boiler happens to be in an adjacent cupboard/room then fine, providing the joints are soldered.
In any case, you do not have to install supp. boding in order to change a CU.


Is this a case of deja vue ?

Firstly as your lighting is outside the zones then you are right, it does not need bonding.
Secondly, if you can proove that the hot/cold and heating pipes are bonded (by measurement) then you do not need to bond them seperately. You need to test for this with an ohm meter and the reading should be below 0.05 ohms. If not then you need to run a 4mm supplimentary bond between hot, cold and heating as said previously.

You can't mesure to prove continuity - the bonding must be done in close proximity to the room - by measuring, you could be reading a H to C a good distance away.

If all you pipework is copper, and lecky outside the zones, then all that is required is a link from H to C anywhere accessible in the bathroom.