Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Selector Switch to Hot Water and Heating
Gain access to PCB (use insulation mat as necessary)
Integral timer in 0 position (Off)
Gain access to PCB (use insulation mat as necessary)
Integral timer in 0 position (Off)
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Test for mains voltage between the black wire (top) on connector X9 and earth.
Isolate as per TOPs P4
and refit as necessary