Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X10 from PCB

Measurement:

Test 1.
Measure resistance across the blue and brown terminals of connector X10.
Expected resistance approximately 160 ohms.
Test 2.
Measure resistance between the brown terminal of X10 connector and a suitable earth connection.
Expected resistance 1 MOhm or greater.