Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
CH Demand
Gain access to PCB (use Insulation Mat as required)
Main On/Off Control in the On position
CH Temperature Control to Maximum
Main On/Off Control in the On position
CH Temperature Control to Maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
If a fault code is displayed press boiler 'Reset' button.
Measure Mains Voltage across connection 4 (L) and connection 5 (N) on boiler connector block.
Measure Mains Voltage across connection 4 (L) and connection 5 (N) on boiler connector block.
Isolate as per TOPs P4
and refit as necessary