I should point out I am NOT an electrician and use this method with a budgie cable/metal locator.
Unless you know how to use a multi meter the only thing you can do is to buy an electric cable/metal locator from DIY store (they do say the pen type with red light on tip are the better ones from electrical suppliers rather than DIY stores) connect the unit up to elecs using the site cable and home socket adapter then set the locator to elecs and run the locator down the cable it should beep and red light flash if current present and stop if and there is a break in any of the two conductors(brown and blue) if it reads right up to connection at c52 then continue by locating the cable inside the c52 up to the zig unit.
Another thought and only a guess is the test button on the zig unit may be stuck in so preventing current from getting through.
bob, October 2011
