Some buildings use closed-circuit television (CCTV), in which surveillance cameras transmit images to monitors. A non-Jewish security guard stationed at the entrance keeps an eye on the people who come and go by watching the monitors. When people whom the guard recognizes as residents of the building or their guests arrive at the front door, he pushes an electric button that unlocks the door, allowing them to enter. Since this system is beneficial to the Jewish residents and guests of the building, a Jew may not stand where his image will be captured on the monitor. Similarly, if a Jew wishes to enter the building, he may not press the intercom button to request that the guard unlock the door for him, since using electricity is prohibited.
Therefore, one should make certain that the place where the guard sits is not far from the front door. Then, when a Jew wishes to enter, he can knock on the door while standing out of camera range, so that the guard can see him and unlock the door for him. If the non-Jew elects to open it using the electric release button, the Jew may still enter, since it is also possible for the non-Jew to open the door manually. If the non-Jew prefers to use the door release button, he is doing so for his own convenience, and not for the benefit of the Jew.
If there is a non-Jew entering the building at the same time as the Jew, even if the non-Jew makes use of the electricity, the Jew can follow him in, since the non-Jew is doing this for his own benefit. If it is a non-observant Jew who makes use of the electricity in order to enter, one may not follow him in, since he may not benefit from melakha done by a fellow Jew on Shabbat. Additionally, this constitutes a desecration of God’s name. Although some are lenient in this regard, it is proper to be stringent. Only under pressing circumstances, when there is no alternative, may one rely on those who are lenient (as explained above, ch. 11 n. 11).
If one wishes to enter a building, but no one inside the building hears him knocking and calling out, may he ring an electric doorbell to gain admission? Some maintain that under pressing circumstances one may ring the bell using a shinui, while others forbid this. Under pressing circumstances, when there is no other solution, one who wishes to may rely on the lenient opinion provided that this leniency is not used regularly, as doing so regularly belittles Shabbat.
. In addition to causing electrical activity, one who stands in a place where his image will be captured on the monitor transgresses Kotev as well (on the rabbinic level, since the image is not permanent). See Orĥot Shabbat 15:35 and 26:27. However, when one has no interest in this happening, he may walk where there are cameras or sensors installed, even though his movements cause electrical activity, as explained in the next section.
. According to R. Shlomo Zalman Auerbach and those who follow him in stating that using electricity is prohibited rabbinically, ringing the bell with a shinui renders his action a shvut di-shvut, and under pressing circumstances he may be lenient. However, for those who maintain that using electricity is prohibited by Torah law, even with a shinui it is still only a single shvut, which remains forbidden. Since according to all opinions, ringing the bell with a shinui renders the prohibition rabbinic, there is a rabbinic doubt about whether this is a case of shvut di-shvut or not. Accordingly, one who wishes may be lenient. As I have written above (ch. 9 n. 7), the entire leniency of shvut di-shvut may be utilized only rarely, under pressing circumstances.
If one accidentally presses a doorbell, he should stop pressing as soon as he realizes what he has done, because this act of stopping is not considered an action. If a light will turn on when he stops ringing the bell, some prohibit this (SSK 23:56). Others permit it, insisting that letting go of the bell is not considered an action. (See Kedushat Ha-Shabbat vol. 2, p. 27.) Under pressing circumstances, one may be lenient.