Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Note: This test can only be carried out on branded / Drayton actuators, if other controls are fitted select that option below
Remove microswitch from the central heating zone valve
Remove microswitch from the central heating zone valve
Measurement:
Test 1:
Manually depress the microswitch and measure the resistance between the grey and orange wires.
Resistance should be short circuit (zero resistance).
Test 2:
Release the microswitch and measure the resistance between the grey and orange wires again.
Resistance should now be open circuit (>1M Ohm or O.L.).
Manually depress the microswitch and measure the resistance between the grey and orange wires.
Resistance should be short circuit (zero resistance).
Test 2:
Release the microswitch and measure the resistance between the grey and orange wires again.
Resistance should now be open circuit (>1M Ohm or O.L.).
Isolate as per TOPs P4
and refit as necessary