One may not activate electrical appliances and devices such as telephones, microphones, alarms, doorbells, fans, air conditioners, and computers on Shabbat. Even if these appliances do not contain an incandescent filament or heating element and do not perform any of the 39 melakhot, it is still forbidden to use them on Shabbat. Aĥaronim disagree, however, whether the prohibition is by Torah law or rabbinic.
Some maintain that using any electrical appliance violates the Torah prohibition of Mav’ir. They maintain that electricity has the same status as fire since, like fire, it has energy and power that can be harnessed. Rav Kook favors this position, arguing that the key aspect of fire is not its appearance, but rather its power to illuminate, heat, and provide power. Indeed, the Sages state that there are different types of fire (Yoma 21b), including some that do not burn and destroy. One example of this is the fire that Moshe saw at the burning bush (Rav Kook, Oraĥ Mishpat §71). R. Uziel agrees with this approach, adding that turning on electricity is also prohibited as a form of Metaken Mana since activating an electrical appliance renders it useful (Mishpetei Uziel, OĤ 2:36:2). Ĥazon Ish (OĤ 50:9) maintains that turning on an electrical appliance is prohibited on account of Boneh, because completing a circuit creates a kli: when electricity flows through a device, an electrical wire within comes to life and activates the device. Thus, one who completes a circuit builds an implement, and one who breaks a circuit demolishes it.
Many others maintain, however, that using electrical appliances that do not contain an incandescent filament and do not perform one of the 39 melakhot is only prohibited rabbinically, as it is considered a weekday activity. Additionally, some maintain that turning on appliances is prohibited because it is creating a new entity on Shabbat (Molid), as it creates a new electrical current in the wires (Beit Yitzĥak). No Torah prohibition is involved, because there is no “fire” in appliances without an incandescent filament. There is no problem of Boneh, because an electrical circuit cannot be considered a kli, that is, an implement or receptacle. This is the opinion of R. Shlomo Zalman Auerbach (Minĥat Shlomo 1:9-12) and R. Eliezer Waldenberg (Tzitz Eliezer 1:20:10).
In practice, le-khatĥila we defer to the opinion that using electricity is a Torah prohibition. In times of need, when there are additional reasons to be lenient, we rely upon those who believe that using electricity is only a rabbinic violation.
. According to Rav Kook, using electricity is prohibited on account of Mav’ir. Therefore, one may not speak into a microphone, as this increases the electric current. His responsa on the subject are not so well known, since Responsa Oraĥ Mishpat, in which they appear (§70-71) was printed in 1979, thirty years after the main debates among contemporary Aĥaronim. At the time, Ĥazon Ish was inclined to say that use of electricity is prohibited by Torah law on account of Boneh, but many disagreed with him, including R. Shlomo Zalman Auerbach and R. Eliezer Waldenberg. Nevertheless, other Aĥaronim share Rav Kook’s opinion that the prohibition on electricity is due to Mav’ir. These include Mishpetei Uziel, OĤ 2:36:2; Yaskil Avdi 5:38; Brit Olam, Ha-mav’ir Ve-hamekhabeh 1; R. Yosef Messas’s Responsa Mayim Ĥayim, OĤ §134. Also see the entry on “ĥashmal” in the Encyclopedia Talmudit, which focuses on the opinions that disagree with Ĥazon Ish and maintain that the prohibition is rabbinic. One should be aware that according to Ĥazon Ish, if an appliance is already on, increasing the current to amplify the power of the appliance is not prohibited by Torah law. However, according to Rav Kook, who believes using electricity is prohibited because of Mav’ir, increasing the current is prohibited by Torah law as well.Many contemporary authorities accept the opinion of R. Shlomo Zalman Auerbach that there is no Torah prohibition involved in using electricity. However, le-khatĥila they still take into account the opinion that maintains it is prohibited by Torah law (see Yabi’a Omer 1:20; Minĥat Yitzĥak 2:112; and many additional works). Igrot Moshe (OĤ 3:42, 3:55, and 4:84) maintains that the status of the prohibition is unclear. In practice, although many state that in principle the prohibition on using electricity is rabbinic, in fact they relate to the prohibition of turning on electrical appliances as if it were prohibited by Torah law. Thus, even in cases of uncertainty and cases where electricity is required for the sake of a mitzva, to avoid substantial loss, or to help someone who is bothered by a minor illness, they are not lenient and prohibit using electricity via a non-Jew or when activated with a shinui, despite the fact that each of these scenarios would constitute a shvut di-shvut (see above 9:11). Only in cases of true necessity do they take into account the opinion that the prohibition is rabbinic. Therefore, the only way these appliances can be used on Shabbat is if they are turned on before Shabbat. In times of true necessity they can be used through grama (above 9:9), meaning that one’s actions will not directly or immediately cause the appliance to turn on. Examples of the permitted use of electricity on Shabbat include wearing a hearing aid (section 3 below) and adjusting the setting on a timer (as explained below in n. 6). For appliances that appear to work normally but have a built-in grama mechanism, see section 18 below. Regarding the use of computers, see below 18:1 and Harĥavot.