I have a "[ring main][1]" with many sockets on it, it is clear that it has been extended over the years. How do I trace the cabling to. - Check that it is a single ring - That only one socket is on each spars - That there are not any other issues. I am hoping for a testing method that I can just apply “set by set”; assume I have access to a good quality resistance meter Is there any software I can type all the resistance readings into that will “solve” the system and will then tell me: - What additional readings it needs - Or how all the sockets are connected. -------- Related but a much easier problem: [Are there any “easy” ways to trace a home electrical system?][2] -------- **Update:** The issue I have with the [standard test method][3] and all current answers is that they assume that the sockets are connect in a single ring – I don’t know how they could detect for example two rings that have their ends joined just before the consumer unit. Or a spars that is connect to anther spars rather then directly connected to the ring. The test in the wiring standard is very good at finding common errors like a wire that is not connected, or a live that is connected to a neutral; however the test seems to assume that the wiring is basically a valid single ring to start with. This is not a valid assumption on an old system you don’t know the history off! [1]: http://diy.stackexchange.com/questions/212/what-is-a-ring-main [2]: http://diy.stackexchange.com/questions/2794/are-there-any-easy-ways-to-trace-a-home-electrical-system [3]: http://www.tlc-direct.co.uk/Book/8.4.2.htm