Set Appliance State:
Set Multimeter to AC Volts 
Turn Hot Water Tap On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the AC voltage between the live and neutral wires on the 3 wire fan connector to the fan assembly.
Expect mains voltage (approximately 240v)
Is the voltage measured as expected?
Expect mains voltage (approximately 240v)
Is the voltage measured as expected?
Isolate as per TOPs P4
and refit as necessary