One may walk where security cameras record images of passersby. Since the pedestrian has no interest in being videoed, he is not held responsible for his image being recorded, and there is no prohibition. Similarly, one may pass through a metal detector, since one who goes through is not interested in its electrical activity. One may also walk on a street where there are motion detectors that detect the movements of passersby. Even if a security system turns a light on when it senses movement, one may walk past it, because he is innocently walking through and is not interested in turning on the light. However, if it is not difficult, it is preferable to use an alternate route, since indirectly causing an electric light to go on is not properly respectful of Shabbat.
A private home might have a security system in which the burglar alarm has been disarmed, but the sensors continue working. Consequently, whenever one passes by certain places, LED security lights go on, or images are recorded. Some forbid walking around in such a house on Shabbat since doing so will cause electrical activity. They maintain that if one wishes to walk there, he must either disable the entire system or cover all the sensors so they will not detect a person’s movements. (See R. Mordechai Eliyahu, She’elot U-teshuvot Ha-Rav Ha-Rashi, 5750-5753, p. 174.)
Others permit walking there. This is because one simply wishes to walk, and has no interest in triggering sensors or having his image captured; the only reason he does not deactivate them is because it is so difficult to do (Si’aĥ Naĥum §25). This is the primary position. Nevertheless, if possible, it is preferable to disable the sensors.
One must disable a light that automatically turns on when one approaches the entrance to one’s house, because he benefits from the light in this case. Even if he does not benefit, it is not properly respectful to Shabbat to cause the light to go on. In a case of need, when the system is activated and there is no other way to enter the house, one can crawl through in such a way that the light might not turn on. Even if it is almost certain that the light will still turn on, turning it on by crawling constitutes a shinui. Additionally, he should keep his eyes closed so that he will not benefit from the light when it goes on.