Set Appliance State:

Mains Power Off
Gas Off
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Rotary Switch to DHW position
DHW Temperature Control To Maximum
Remove side access panel from Pump.
Hold in Boiler Case Switch
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

With side access panel removed measure Mains Voltage across Live (Brown) and Neutral (Blue).