Set Appliance State:

Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage between the brown and blue wires at the mains terminal block.
Mains voltage should be present.
Note:
Overheat stat may not be present, this does not affect test.