A few weeks ago, I posted a video of an unsafe motorized garage vehicle door -- door failed to auto-reverse at floor level when it struck a 1-1/2" flat object that had been placed on the floor. A garage vehicle door, to be considered safe, must auto-reverse at floor level (1-1/2" over the floor or higher) and at mid-height. Any reasonably new garage vehicle door should, also, have sensor-eyes, both sides of the door at the bottom, that cause the door to reverse if there is an interruption of the infrared beam that exists between the eyes.
Let's review: First, here is a door that fails to auto-reverse at floor level.
Now, let's take a look at a garage vehicle door that auto-reverses correctly.
This video, shot in Bellingham, gets the point across -- some doors really do auto-reverse at floor level. I have had sellers argue with me that they never heard of such a test. These folks were under the impression that the sensor-eyes are the only safety feature of significance. That is, obviously, far from the truth. Keep in mind that many older doors may reverse only at mid-height, or not at all. Such doors are, by today's standards, considered to be unsafe. Performing "impact" safety tests at any old door, or at a door that is out of adjustment, may result in damage to the door, related property damage or injury so all safety testing should be performed trained professionals.