Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
User display control to HW and CH
Remove control box cover if necessary
Remove control box cover if necessary
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the Voltage between the Blue wire in the connector block (top connection) and the neutral at the incoming mains terminal strip
Expect mains voltage.
Expect mains voltage.
Isolate as per TOPs P4
and refit as necessary