I'm about to replace a dimmer switch in my house (UK - Single Phase) and every wire in the backbox is red, while I've tested and identified each (live in, live out, neutral in, neutral out, neutral to light and switched live). I was seeing something strange when testing with my multi-meter...earth-live 240v - ok, earth-neutral 0v - ok, live-neutral 115v. The latter starts around 180v and settles down @ 115v while I'm measuring. Any ideas what would cause that? Bad multi-meter?