Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
Turn Hot Water Tap On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Reset appliance as necessary.
Approximately 8 seconds after mains power is turned on, measure the voltage between the black and blue wires on X7 connector at the PCB.
Mains voltage expected.
Approximately 8 seconds after mains power is turned on, measure the voltage between the black and blue wires on X7 connector at the PCB.
Mains voltage expected.
Isolate as per TOPs P4
and refit as necessary