Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Gain access to the installer connections
Ensure Central Heating and DHW are turned OFF
Ensure Central Heating and DHW are turned OFF
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure voltage between CH on the yellow connector
(marked LR with a radiator symbol) and mains neutral.
Mains voltage should be absent.
(marked LR with a radiator symbol) and mains neutral.
Mains voltage should be absent.
Isolate as per TOPs P4
and refit as necessary