My house has a PME system, and there are bonding cables connecting ground on the distribution board to the water main and to the gas pipework immediately after the meter, which I believe is the normal arrangement.The gas meter is located in an attached garage.
When last tested and updated, the gas meter was the traditional metal type and the gas main was cast iron, so both of these bonding cables were effectively connecting the distribution board ground to earth. Since that time two things have changed:
1. The gas meter was replaced by a smart meter, which appears to be at least partly plastic; however, I imagine that the metal mounting bracket still provides connectivity between inlet and outlet. When this was done the installers attached a label saying that there appeared not to be equipotential bonding which I admit I ignored, since to my mind this was clearly present.
2. The gas pipe was replaced by a plastic one; however, this is threaded through the old cast iron one between the edge of the property and a metre or so short of the gas meter. This means that there is no longer an electrical connection between ground on the distribution board and what remains of the cast iron gas pipe in the garage.
My question is simply, does this pipe need to be bonded to the remainder of the gas installation (and therefore the distribution board ground)? On the face of it, a person in the garage could quite easily touch both that pipe and the other sde of the meter (or indeed any electrical equipment in the garage grounded to mains earth) which would suggest that such bonding might be required, but on the other hand they could equally well touch the fabric of the building instead of the gas pipe, which would suggest that it would not make any difference. Another factor is that the installation ground (in the event of a fault in the supply neutral conductor) now only has one route to earth rather than two, so its impedance must surely be higher, but again, is this something that matters since I don't believe it was ever measured?
