@Picbuster when my door is down it's down. Can't be opened because the garage door opener (GDO) doesn't allow for that. Post #1 the TS stated he has a Chamberlain. That's a GDO if I've ever heard of one. An automatic garage door position sensor such as I've built works nicely. AND it doe not require human intervention. Power failures? Rare. And usually don't happen for long. My GDO Closer circuit has several times a day it checks for an open door. If power goes out for one hour, the next sense period will close it. And my timer is battery backed up. In fact, I have one I just put away for the season. I used it for Christmas light timing. It keeps time well over a year without power. And if it goes dead in the meantime plugging it in charges the battery and you can reset the time. So if the one controlling my GDO should see a power failure, unless that failure is a year long - I'm going to discover it's open at some point.