Come across something I've not seen before. Basically from what I can gather a mains water stop cock & sink has at some point been moved to a different location in a kitchen. What we have is main water pipe (copper or similar) entering building at old stop cock location & there is a 10mm earth clamped to it, the plumber has then used a white plastic pipe to supply the feed to the new stop cock & sink location but this joins to copper under kickboards so that everything you see under sink is copper. Outwith the sink once they go under kick boards it turns back to plastic, the hot pipe included. They also have a 10mm earth clamped underneath sink between hot & cold copper pipes. Surely this isn't the correct way of doing it?