Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Remove the spark lead from the spark generator
Function selector in standby position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Function selector to DHW position.
Allow fan to start.
After approximately 5 seconds can sparking be seen across the exposed terminal of the spark generator and the earth terminal on the generator?