PEAKMETER MS5910 RCD Loop Circuit Tester Multimeter GFCI Loop Resistance Tester The RCD Tester brings the latest technology into an instrument which is compact, firm, durable, simple to use and convenient to carry. It can measure trip-out current, trip-out time, loop resistance, and online voltage, frequency measurement etc. High speed Microprocess ICs to make sure its reliability . stability and accuracy. It is the ideal tool for electrical inspection and repair. t's widely used in Electricity, Aarchitect, Electrical Installation area etc.