Many institutions, including hospitals and homes for the elderly, have automatic doors. Sensors indicate when a person approaches (usually sensing that the person has passed through a ray of light) and open the door for a short time, immediately closing it afterwards. The purpose of such doors is to maintain an air conditioned environment and to prevent wind from entering the facility. These doors are not only convenient to use but also provide a distinct advantage for the disabled and the infirm who might have trouble opening a door manually. Another advantage is the fact that the door is touched less and therefore does not have to be cleaned so often.
What can be done on Shabbat? Must we always wait for a non-Jew to enter, so that we can "hitch a ride?"
The Zomet Institute has developed a solution for this problem that is suitable according to the most stringent halachic rules. A mechanism disconnects the sensors and opens and closes the door on a preset cycle (as is desired at the installation). For example, the door might be closed for five minutes and open for twenty seconds.
How can we tell that a door has such a device installed? How can we know not to approach the door, an act which will operate the automatic mechanism, which of course will not be turned off on Shabbat? The answer is that such a signal light is installed next to the door. A red light is a warning not to approach the door, while a green light means that the automatic mechanism is disengaged and it is safe to enter. There is also a yellow light, warning that the light is about to turn red. In fact, the whole device works just like a regular traffic light.
Obviously, when there is a mortal danger or even the possibility of danger, it is not necessary to wait for a green light. One should then enter the door in the regular way, as quickly as possible.
For details and ordering information, contact The Zomet Institute.