Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Voltage 
CH Demand
Control Thermostat in high position
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage across connection 1 (Grey wire) on connector CM1 on the Interconnection Board and the Neutral wire (Blue) marked N on the main connector block located on the Interconnection Board.
Isolate as per TOPs P4
and refit as necessary