The MPI-535 meter is designed for checking home and industrial electrical installations. The measurements that can be made, by using the device, provides the results which determine the safety of the installation. The instrument allows make a set of measurements of the parameters of protection against electric shock using a single universal device. Significant automation of measurements of the meter makes possible to test functioning of residual current circuit breakers in the Auto mode, as well as in pre-programmed measuring sequences (so-called auto-tests), which can also be extended with own sequences. Automatic measurement of insulation resistance of 3-, 4- and 5-wire conductors is possible by using additional the AUTO ISO-1000C adapter.