Multifunction device for earth resistance testing without tripping and RCD testing The M73 is designed for operators primarily working on private installations. It is very easy to use, compact, and performs all necessary tests to establish COMPLIANCE (and thus ensure SAFETY) of the electrical system. Always use it before starting work on an existing system (which the operator may not be fully familiar with) and after completing work, this device guarantees safety for both operators and users of electrical systems! Its small size offers many operational possibilities. The M73 is also used for electrical system safety verification; it can measure earth resistance without tripping, test Type A and AC RCDs, and measure insulation and circuit continuity. After testing, it displays all results with compliance or non-compliance indication using simple OK or NOT OK symbols.