Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Voltage Set meter to measure AC Volts
CH Demand
Remove lower facia panel
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across connection CI on connector block X2 and the neutral (marked N) on connector block X1. Both connector blocks are situated at the bottom L/H side of the PCB.
Note:
If no programmer is fitted a link will be present between "Cl" and "CL".