The “Sabbath Mode” Oven Controversy by Rabbi Chaim Jachter


Sivan 5768 saw a pronouncement of leading Poskim in both Israel and North America forbidding pressing buttons on Sabbath mode ovens on Yom Tov.  A permissive ruling was previously issued by Rav Moshe Heinemann, the rabbinic administrator of the Star K certification service.  We shall present the basis for Rav Heinemann’s ruling (as I understand it) based on both Hebrew and English language articles accessed from the Star K website and a reason why so many Poskim strongly object to his approach.

Background Information Regarding Grama

Since Sabbath mode ovens allow for raising and lowering the temperature in an oven by means of Grama, indirect action, it is necessary to review the application of Grama in the modern environment.  Last week we explored the issue of Grama in the context of refrigerators.  We presented the ruling of Rav Shlomo Zalman Auerbach permitting the opening of a refrigerator door even when the motor is not running despite the fact that opening the door will inevitably trigger the motor to go on earlier than it would have had the door not opened.  In short, Rav Auerbach ruled that the impact of opening the door on the motor is indirect (Grama), and Grama is not prohibited when one does not intend to cause the resulting direction.  Since one who opens the door intends to take food and not to trigger the motor, indirectly causing the motor to go on earlier is not prohibited on Shabbat or Yom Tov.

There are cases, however, where Grama is permitted even when one’s intention is to cause the resulting act.  For instance, the Shulchan Aruch (Orach Chaim 334:22) permits one to place barrels of water in the path of a fire so that the heat will burst the barrels causing the water to come out and extinguish the fire.  Rama (ad. loc.) cautions, however, that the permission to intentionally perform an act of Grama is limited to case of avoiding great loss, such as putting out a fire.  Biur Halacha (ad. loc. s.v. DeGram Kibui) clarifies that this rule applies to all of the 39 Melachot (forbidden activities) of Shabbat and not only to Mechabeh (extinguishing).

The Torah (Shemot 20:10) states “Lo Ta’aseh Melachah”, do not perform Melachah on Shabbat.  The Gemara (Shabbat 120b) infers that performing a Melachah is forbidden but indirectly causing Melachah is not forbidden.  Rama, in turn, understands that Chazal created a rabbinic prohibition to indirectly cause Melachah on Shabbat in situations other than a case of great need.  Danger to life is not required to permit Grama; rather, great need is sufficient cause.  In other words, Grama is permitted for essential needs even if they are not life threatening needs. 

The reason for this clearly seems to stem from concern that if Grama was permitted in all situations on Shabbat, Shabbat observance would be eviscerated as all work could be accomplished on Shabbat as long as it is done indirectly.  Ramban (commentary to VaYikra 23:24) notes that, due to this concern, Chazal forbade a host of activities, such as engaging in business deals and asking a non-Jew to perform Melachah on one’s behalf.  Chazal wished to avoid one who on the one hand does not technically violate Shabbat but on the other has not observed a meaningful Shabbat. 

Contemporary Applications of the Grama Principle

The Gemara (Sanhedrin 77a) presents a situation of Grama referred to as “Sof Chamah Lavo,” which twentieth century authorities have applied in a variety of situations.  The Gemara describes a case where one ties up another individual in the desert during the night and the sun rises the subsequent day and kills the victim with its heat.  The Gemara classifies this as an act of Gram Retzichah (indirect killing), explains Rashi (ad. loc. s.v. Kofto and s.v. Oh ShePara), since the killing agent was not present at the time of the perpetrator’s action.

The Chazon Ish (O.C. 38:4) applies the Sof Chamah Lavo principle to solve the need to milk cows on Shabbat (see the discussion in my Gray Matter One pp. 200-214).  He permits attaching the milking machine pipes to the cow’s udder before the electric flow begins.  The machine can subsequently be turned on by a timer and the one who attached the pipes to the udder is considered to have milked indirectly.  Since the electricity is not flowing when the pipes are attached, it is analogous to the sun not being present when the individual tied up another person in the desert.  The Chazon Ish permits this due to the great need for milking cows on Shabbat both in terms of relieving suffering of the cows and severe financial strain on dairy farmers. 

Another application is the Shemirat Shabbat KeHilchatah’s (13:25) permission to adjust certain timers to turn on a light earlier than scheduled, in case of great need.  Once again, since the electricity is not flowing when he adjusts the timer, it is comparable to the sun not being present at the time when the deed is done. 

The Zomet Institute, an establishment in Alon Shevut, Israel that seeks to find engineering solutions for many contemporary Halachic challenges, produces many items that operate using the Sof Chamah Lavo principle for use in highly essential but not life threatening situations.  These gadgets include wheelchairs, hospital equipment and vehicles for patrolling areas in Israel that are not exceptionally dangerous.  (For an explanation as to why Grama is preferable to Amirah LeNochri, instructing a non-Jew to perform Melachah, see Rav Yaakov Ariel’s Techumin {19:343-348} and Rav Shmuel David’s Teshuvot MeiRosh Tzurim {number 36}.)

 A popular Zomet product is their “Grama phone,” which operates as follows.  When one raises the receiver an electric circuit is not completed as happens in a conventional phone.  Instead, an electric pulse is sent out by the phone every ten seconds or so to detect if the receiver has been lifted.  When it detects that the receiver has been lifted the circuit is completed.  Yet again, the absence of the pulse when one lifts the telephone parallels the sun which is not at hand when the act is completed.  Rav Ovadiah Yosef endorses the use of the Grama phone for essential needs in a brief responsum printed in Techumin (1:518) The Grama phone is used in many venues in Israel, especially in the Israel Defense Forces which has purchased hundreds of these phones for use in essential but not critical situations on Shabbat.  Grama phones have greatly enhanced Shabbat observance in the IDF, as a Grama phone is used instead of a regular phone, except in case of a full-fledged emergency. 

We should note that Rav Yosef Dov Soloveitchik (cited by Rav Hershel Schachter in his BeIkvei HaTzon number 7) does not subscribe to the Chazon Ish’s application of the Sof Chamah Lavo principle.  Rav Soloveitchik argues that since the electricity is operational when one performs his actions it is not analogous to the classic cases of indirectly extinguishing a fire or Sof Chamah Lavo where the “active item” is not present when one acts.  One may respond (see my essay printed in Yeshiva University’s Beit Yitzchak 35:382-383) that in the classic cases the natural forces moving the fire and the sun (from a common sense perspective) are extant when the action is performed, just as the electricity moving the timer is present at the time when one acts.  Accordingly, it would be accurate to say that the timer itself parallels the classic fire and sun rather the electricity driving the timer.  The electricity parallels the natural forces that drive the sun and fire. 

Rav Heinemann’s Application to Yom Tov and Sabbath Mode Ovens

Rav Heinemann argues that Grama is permitted in all situations on Yom Tov.  He bases this on a ruling of Rama (O.C. 514:3) permitting one to place a candle in a location where the wind is not currently blowing and a strong wind will later come and extinguish the fire.  The Magen Avraham (ad. loc. number 5) questions why Rama does not limit this ruling to a case of great need as he did in the aforementioned context of extinguishing a fire on Shabbat.  The Sha’ar HaTziyun (514:31) cites the Ma’amar Mordechai who writes that “perhaps” Yom Tov differs from Shabbat in that only on Shabbat does Rama limit Grama to a case of great need but it is permissible in all situations on Yom Tov.  Rav Heinemann understands the Sha’ar HaTziyun as a full endorsement of this distinction. 

Rav Heinemann applies this to an oven that is modified with a “Sabbath mode” adjustment with a random delay feature.  He permits pressing keys on a keypad since nothing happens when doing so.  Instead, the oven will randomly look to the setting and adjust the temperature.  There is an interval of between fifteen and twenty five seconds before the heating element is activated in such specially modified ovens.  Rav Heinemann permits pressing the keys in all circumstances on Yom Tov since he believes that Grama is permitted in all circumstances on Yom Tov.

Criticism of Rav Heinemann’s Ruling

This past spring saw a flurry of rulings from many top level Poskim in Israel and North America forbidding the pressing of buttons on Yom Tov.  These Poskim include Rav Yosef Shalom Eliashiv, Rav Shmuel Wosner, Rav Nissim Karelitz and Rav Moshe Shternbuch in Israel as well as Rav Yisrael Belsky, Rav Feivel Cohen, Rav Shmuel Fuerst, and Rav Mordechai Willig in the United States.  In addition, those rabbis who follow Rav Soloveitchik’s definition of Grama certainly do not subscribe to Rav Heinemann’s approach. 

 Rav Shternbuch in particular seemed very concerned about the use of Grama on Yom Tov especially since there are so many electronic items that can be operated using the Grama principle.  For example, if one were to follow Rav Heinemann’s to its logical conclusion one could routinely use a Zomet Grama phone on Yom Tov, an obviously intolerable situation according to all opinions. 

Moreover, the idea that Halachah grants unfettered license to perform Melachah using Grama on Yom Tov does not seem to be supported by Poskim.  The Kitzur Shulchan Aruch (98:25) does not permit Grama on Yom Tov and the Aruch HaShulchan (O.C. 514:11) does not articulate a distinction between Grama on Shabbat and Yom Tov.  The Shemirat Shabbat KeHilchatah (13:27 and 33) does not grant blanket permission to Grama activities on Yom Tov and the Zomet Institute does not sanction use of its Grama products on Yom Tov for non-essential activities.  Even the Sha’ar Hatziyun presents the Ma’amar Mordechai’s approach as merely “possible.”  Hence, intentionally performing Grama is permissible on Yom Tov only for highly essential needs and not simply to raise and lower the temperature in one’s oven. 


Rav Heinemann and the Star-K certification agency are highly respected and are held in the highest regard.  However, for the reason articulated above as well as reasons presented by the aforementioned Poskim, Rav Heinemann’s ruling appears difficult and should not be relied upon in this specific instance.

Rav Eliezer Waldenberg (1915-2006) – An Appreciation by Rabbi Chaim Jachter

Opening Refrigerators on Shabbat by Rabbi Chaim Jachter