Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Voltage 
Control Thermostat in the Off position
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across connections N (Blue wire, Neutral) and L (Brown wire, Live) on the main connector block located on the Interconnection Board.
Isolate as per TOPs P4
and refit as necessary