The MT312 is a compact, versatile tester designed for 3-wire AC circuits, supporting ELCB/RCD testing, loop impedance measurement, and polarity verification. It features a Non-Contact Voltage (NCV) function for safe AC voltage detection and displays wiring status clearly on a large, easy-to-read LCD screen. Voltage measurements between Live and Neutral, as well as Neutral and Earth, are shown directly on the display. The MT312 automatically performs loop impedance testing to verify correct wiring, with intuitive LED indicators: Green for Good, Orange for Check Circuit, and Red for Urgent Check, highlighting any potential faults. During ELCB/RCD testing, the device measures fault trip times up to 99.9ms, with a 10-second buzzer alert confirming a successful trip. A key feature of the MT312 is its interchangeable leads, enabling testing of standard power outlets with the included test leads or distribution boards using the optional MT350L test lead set.