Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
Models with Programmer: Rocker Switch to Timed, Programmer C/H demand to ON.
Models without Programmer: Central Heating Switch to ON.
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure Mains Voltage across Connection 10
(on the 12 way Terminal Block) and the Main
Appliance Neutral Connection.