Unplug the machine, turn all switches to the off position. The unit should be cold (Ready light off)

Set the multimieter to test resistance (Ohms). Connect one of the test leads to the power plug Ground prong (rounded prong) of the machine.

Touch the other lead of the multi-meter to the espresso machine chasis. Resistance should measure very low - near zero Ohms.

Line (Black) to chassis Ground - should be open circuit (no continuity) - any other result would be a serious fault condition, the machine should not be operated.

Neutral (White) to chassis Ground - should be open circuit (no continuity) - any other result would be a serious fault condition, the machine should not be operated.