Hopefully this is the last set of questions!


1) My current installation is PME with the following differences from
the diagram in the OSG:

All the conductors (supply and main equipotential) are 6mm2 (diameter is
4.4mm so it's either 6mm with .8mm insulation, or 10mm with .4mm - 6mm
sounds more likely!)

As far as I can tell, the gas pipe is not directly bonded to the main
earthing terminal. The water pipe is, and then there is a second wire
running away from the water pipe, which I believe connects to the gas pipe.

There is no separate main earthing terminal - it's more of an integrated
one. The CU earth connects to a terminal at the side of the supply fuse,
as does the water bond. I don't see any more terminals for adding a
third (gas) bond there.

meter tails are 16mm2 (as are the fuse-meter conductors)

When I put the new CU in, I will provide 25mm tails and a 16mm CU earth
for the supplier to reconnect (I assume I'm not allowed to touch
anything on their board so they will want to do this bit). Is there any
chance that they will refuse to reconnect me because my main bonding
conductors aren't up to scratch? As I understand it 6mm2 is OK, just
doesn't comply - there's even an example PIR in Appendix 7 illustrating
this precise case - TN-C-S with 6mm earth. However, I don't (yet)
understand why TN systems require a higher main bonding csa than TT, and
things I don't understand bother me!

2) Is there anyway of testing the continuity of the main bonding without
using a long test lead? There is no neutral to use on a gas pipe....
Would it be acceptable to temporarily run a second lead, calibrate its
resistance and deduce R2?

Thanks!

Ben