I believe they are set up that if any voltage what so ever is present they will be illuminated. The reason is that with no voltage present, they are set to revert to 100%. That way they can still be used even if something went wrong with your controller. The best way to have them turn completely off is to have the power cords run through timers. During times when the timer is one, you controller would control the brightness but when you want them completely off, let the timer kill the power to the fixture. Hope that helps.