Set Appliance State:

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

Measurement:

Measure the voltage across live terminal marked Ls and the
neutral terminal marked Ns at the green terminal block
on the PCB.
The terminal block is located at the back of the PCB behind
the transformer.