You can test the Zs on the motor fed by a soft-start with the motor running, with your loop tester. A continuity test of the invertor or whatever motor Earth to the switchgear would be normal, as the flexible conduit can hide many sins! This will probably not work at all with an inverter supply and may well damage the tester. Supplementary bonding of fixed machinery is also a good idea, Earth wires seem to have a habit of failing in machinery power arrangements for some reason, probably because they do not show up for notice as power failure does.
You can test the Zs on the motor fed by a soft-start with the motor running, with your loop tester. A continuity test of the invertor or whatever motor Earth to the switchgear would be normal, as the flexible conduit can hide many sins! This will probably not work at all with an inverter supply and may well damage the tester. Supplementary bonding of fixed machinery is also a good idea, Earth wires seem to have a habit of failing in machinery power arrangements for some reason, probably because they do not show up for notice as power failure does.
