Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across the live (marked Lp) and the neutral (marked N) on the main connector block at the front of the control box.
Isolate as per TOPs P4
and refit as necessary