Excuse me if this has already been discussed. When studying Scott's excellent diagram of PME I note that the neutral and ground are bonded at the service main just as in the USA. Thus the neutral can flow on the bond to the water pipe in parallel with the neutral going back to the transformer. The water pipe interconnects with other services so the current can use their neutrals as part of the parallel path.
This parallel current can be a significant percentage of the service neutral, particularly if there is some corrosion or looseness in the service neutral.
When I was wandering around London and other cities in the Southwest during two visits I turned on my gaussmeter and found strong fields from currents under the sidewalk and streets, just as I find in US cities. I was able to verify at times that the fields were from water pipes.
Since the magnetic fields on the service cables are identical to those on the water pipes, these fields can affect computer monitors and other sensitive electronic instruments, even if the health concerns are ignored. My question (at last!) is whether there is any attempt in the UK to insert insulating connectors or spacers in the water system to stop these random currents?
Karl
Sinc
