Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow the boiler to run in DHW mode.
Measure the AC voltage between the L terminal at connector X15 on the PCB and the earth at the incoming mains connector.
Expect approximately 240 VAC.
Is the voltage measured as expected?
Measure the AC voltage between the L terminal at connector X15 on the PCB and the earth at the incoming mains connector.
Expect approximately 240 VAC.
Is the voltage measured as expected?
Isolate as per TOPs P4
and refit as necessary