Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Remove ignition electrode from the burner door
Screw the ignition electrode onto the heat exchanger mounting bracket (as shown)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance as required.
Allow appliance to commence its ignition sequence.
Approximately 5 seconds after the fan has started,
can sparking be observed between the electrodes?