- Posts
- 7,872
- Location
- East Midlands
Water on its own isn't a terribly good conductor. Stick your test meter terminals in your cup of tea and you'll see what I mean. Than add salt and watch the resistance drop. The plumbing's supposed to be attached to earth where it enters the house, even if the water comes in via a plastic pipe (typically black in the 1970s and blue more recently). You need a fair amount of contact between the conductor and the soil to keep the earth resistance low, hence the hammer-in earth rods usually being 4ft long. At the consumer unit you usually find the earth attached to the outer casing of the incoming cable, which seems to suffice for most electricity suppliers.