Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Observation:
Ensure there is no demand for heating.
Measure voltage across the tip of the spark electrode and the earth terminal on the electrode.
Expected voltage approximately 190V AC.
Measure voltage across the tip of the spark electrode and the earth terminal on the electrode.
Expected voltage approximately 190V AC.
Isolate as per TOPs P4
and refit as necessary