Here's the problem: it's an European house question, I have an outdoor switch which has been wired a long time ago to a pump. Usually we have three wires, a blue, a brown and a green/yellow for grounding. Have been asked to connect a buzzer and a led to the switch directly I would have usually use a AC/DC 12V converter and that would be fine. In the switch there is a only one lead wire, it's blue and lights up the electric tester screwdriver, other wires, the brown and yellow have been connected to the pump directly, totally bypassing the switch. Here's the question: the converters for 220V/12V has input for two live wire, what can I do with an only one lead? Thank you in advance, please excuse my amateurism.