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?

  • High-impedance digital multimeters can pick up voltage from adjacent wires. They are not appropriate tools for such measurement, unless you put a load resistor, perhaps 200,000 ohms, across the meter's leads. Jun 11 at 2:21
  • You could say that, it's a "defect" in almost all DVMs. Search our system for questions about "phantom voltage", that's what you're dealing with here, and this question is a duplicate of any of those. Jun 11 at 17:57

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