Adjusting Timers on Shabbos
Question: Is it permitted to adjust a Shabbos clock (timer[i]) to turn on or off a light or an appliance[ii] sooner or later than originally planned?
Discussion: There are a number of halachic concerns involved in adjusting timers. There is a possible issue of violating the melachah of kindling (mav’ir), since this action directly or indirectly causes the light to go on (when the clock is adjusted to turn on a light sooner than originally planned). There is a concern of makeh bepatish, since some Poskim hold that adjusting a timer is a form of tikkun mana. There is also a debate as to whether or not the timer itself or its parts, e.g., the dial or trippers, are muktzeh. Contemporary Poskim have different views regarding all of these issues.
The practical halachah is as follows: Many Poskim rule stringently on all (or most) of the halachic concerns stated earlier and thus forbid – either by Biblical or rabbinic law – adjusting a time clock under all circumstances.[iii] In their view, once a timer is set it may not be adjusted and is completely off limits. Other Poskim are more lenient and permit adjusting the timer so that the lights are turned off, or on, at a later time that that originally planned.[iv] They reason that when the electricity is already off or on, extending its present state is merely allowing the status quo to continue. All Poskim agree, though, that even in situations where the essential halachah permits adjusting the timer, one should not do so unless there is a pressing need.[v] It is, however, permitted to ask a non-Jew to adjust a timer if necessary for the sake of performing a mitzvah or to avoid a major loss.[vi]
[i] Our Discussion deals with timers which are adjusted manually; digital timers are forbidden to be adjusted in all cases.
[ii] Using a Shabbos clock to run an appliance (other than lights) on Shabbos is a matter of some controversy. While many Poskim are lenient and the widespread practice is to use a Shabbos timer for many appliances (except for dishwashers or other machines that make noise), Rav M. Feinstein (Igros Moshe, Orach Chaim IV, 60) strongly criticizes the practice as undermining the sanctity of Shabbos, and asserts that it would certainly have been forbidden by Chazal had this technology been available in their days.
[iii] Chazon Ish, quoted in Orchos Rabbeinu, I, 170; Igros Moshe, Yoreh Deah III, 47:4; Orach Chaim IV, 91:5; Minchas Yitzchak III, 37; Rav Y.S. Elyashiv, quoted in Ashrei Ha’ish, Shabbos 19:31.
[iv] Minchas Shlomo I, 13; Yabia Omer III, 18; Shemiras Shabbos Kehilchasah 13:28. Under extenuating circumstances, e.g., to relieve the distress of someone who is ill, these Poskim permit adjusting the timer to turn off the light sooner than originally planned as well.
[v] Orchos Shabbos 29, notes 26 and 29, quoting Rav S.Z. Auerbach (oral ruling).
[vi] Ashrei Ha’ish, Shabbos 19:31; Minchas Shlomo I, 10:6.