Why perform this test?

If you miswire the GFCI, it may not prevent personal injury or death to a ground fault (electric shock). If you mistakenly connect the LINE wires to the LOAD terminals, the thermostat faceplate will not illuminate after installation. 

How to perform this test? 

1. Verify the thermostat's fault light is off. If it is on, press the reset button.
2. Turn the heater on to the maximum temperature setting, and wait ten minutes.
3. Press the test button. If the fault light illuminates and after 5-10 minutes the floor heater cools off, you have installed the thermostat correctly.
4. Press the reset button to end the test.
5. Repeat this test once a month to ensure proper operation.