The Megger MTB7671/2 Instrument Test Box is a multifunctional calibration device designed to verify the performance of electrical installation testers between formal calibrations. Housed in a robust carry case, it enables on-site checks of insulation resistance, continuity, loop impedance, RCD operation, and voltage measurement functions. This portable checkbox supports compliance with standards such as BS7671, BS EN 61557, and IET On-Site Guide recommendations. Colour-coded test points and clear pass/fail indicators simplify use, while included result cards and test labels help maintain a documented record of performance checks. Features and Benefits Verifies key tester functions: insulation resistance, continuity, loop impedance, RCD operation, and voltage measurement Provides insulation resistance test voltages at 250V, 500V, and 1000V, with resistance values at 9M and 90M to verify measurement accuracy Offers continuity testing with resistance values at 0.5 and 5, ensuring corr