Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Selector Switch to Hot Water and Heating
Gain access to PCB (use insulation mat as necessary)
Gain access to PCB (use insulation mat as necessary)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across the live brown (4) and neutral blue (3) leads at connector marked X3 on the PCB.
Expect mains voltage.
Replace the cover after test.
Expect mains voltage.
Replace the cover after test.
Isolate as per TOPs P4
and refit as necessary