Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
On/Off Switch ON
Gain access to PCB (use insulation mat as necessary)
No demands
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the AC voltage between the Blue and Black wires at the incoming mains connector on the PCB.