Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Remove cover from the room thermostat
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage between the common of
the room thermostat and a suitable earth.
Is mains voltage present on the common
connection?
Note: The colour and position of the
wires will vary between systems and components.
the room thermostat and a suitable earth.
Is mains voltage present on the common
connection?
Note: The colour and position of the
wires will vary between systems and components.
Isolate as per TOPs P4
and refit as necessary