The Velleman Live Wire Detector Kit can detect device wires that are very easily checked for mains voltage... The K7101 can be used to search for wires installed in or behind walls or to trace interruptions in wiring. A flashing LED indicates whether or not voltage is present. The flashing speed indicates how close by the wire is. If an audible signal is also desired, space has been provided on the PCB for buzzer SV4/12-S to be connected. The PCB has been specially constructed to fit entirely into the separately available box type G407.