Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Voltage Set meter to measure AC Volts
Ensure secondary heat exchanger is cool and there is a demand for Preheat
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Apply DHW demand.
Measure voltage across brown lead (live) and pink lead (neutral) at PCB side of inline connector.