Set Appliance State:
Set Multimeter to AC Volts 
CH Demand
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the resistance between the black wire at the selector switch and the neutral at the incoming mains terminal strip.
Expect mains voltage.
Is the voltage measured as expected?
Expect mains voltage.
Is the voltage measured as expected?
Isolate as per TOPs P4
and refit as necessary