Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Selector Switch to Hot Water and Heating
No Demands for CH
Gain access to PCB (use insulation mat as necessary)
No Demands for CH
Gain access to PCB (use insulation mat as necessary)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the AC voltage at the black wire on the incoming mains terminal strip that leads to the PCB connector X3 and the incoming neutral.
Note:
On some appliances the incoming terminal strip is located differently and has been rotated through 180° from the one shown.
Note:
On some appliances the incoming terminal strip is located differently and has been rotated through 180° from the one shown.
Isolate as per TOPs P4
and refit as necessary