Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to mVolts DC 
Clip one lead of multimeter to thermocouple sheath
Light Pilot, and keep gas control knob depressed throughout test
Light Pilot, and keep gas control knob depressed throughout test
Gas On; Pilot On
Measurement:
Remove right hand wire from interrupter and connect other multimeter lead to the exposed interrupter terminal.
Measure the voltage.
Measure the voltage.
Isolate as per TOPs P4
and refit as necessary