Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Gain access to PCB (use Insulation Mat as required)
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Ensure there is no CH demand before carrying out this test.
Measure voltage across Terminal block X5 connector 2 (L) and Terminal block X4 connection 2 (N).