Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Selector switch set to DHW
DHW temperature control set to MAX
Preheat switched OFF
Remove the HT lead from the spark electrode and trap it below the ignition electrode and behind the earth lead
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Apply a DHW demand.
Allow appliance to go through it's ignition sequence.
Is sparking observed at the end of the ignition lead?
Note.
1. Stand well clear of the appliance during the ignition sequence.
2. Appliance may enter lockout during this test, reset as required until test is complete.