This latest set of multifunction installation tests expands the nomenclature and enormous value of these testers. The range of 3 instruments is expressly used to test electrical low voltage systems according to BS7671. They offer all the tests required to complete the required electrical certification for fixed-wired installations in industry, commercial and residential areas. MFT1721 (1008-123) – The most popular tester that offers all the advantages of the MFT1710, including automatic RCD testing and adding phase rotation, 3-phase RCD testing and current measurement with the optional clamp. This now adds an additional 100V insulation test area, a true RMS voltage measurement, a MV sensor input and type B RCD test.