Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
DHW Demand
Set the cylinder thermostat to its maximum position
Remove cover from cylinder thermostat
Remove cover from cylinder thermostat
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
CAUTION: All terminals of the thermostat are potentially live during this test.
If this test cannot be carried out with the thermostat attached to the cylinder then it must be placed onto a stable surface.
Measure the voltage between the cylinder thermostat common (C) and a suitable earth.
Is mains voltage measured on the cylinder thermostat connection?
Note: The colour and position of the wires will vary between systems and components.
If this test cannot be carried out with the thermostat attached to the cylinder then it must be placed onto a stable surface.
Measure the voltage between the cylinder thermostat common (C) and a suitable earth.
Is mains voltage measured on the cylinder thermostat connection?
Note: The colour and position of the wires will vary between systems and components.
Isolate as per TOPs P4
and refit as necessary