Will The Kosher Switch Bring Mashiach?

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by R. Gil Student

Because of renewed publicity about this product, I am reposting this essay from four years ago. Not long after this was published, R. Yehoshua Neuwirth wrote that he did not approve this product and R. Nachum Rabinovich communicated the same. Other rabbis who were supposedly supporters also claimed they were misrepresented.

As technology changes, the proper application of halakhah may require changing practice to remain in step with the new reality. However, when evaluating new technology we have to look at reality and not hype. The new “Kosher Switch” (link) is billed as a game-changer that will radically redefine the practice of Shabbos. In truth, it is a next-generation “Gerama Switch” that seems to this writer to fall short of the requirements of many major authorities. To fully understand the product and why its halakhic implications are probably minimal, we have to wade through some background.

I. Gerama

Over a century ago, halakhic authorities debated the status of a standard light switch. R. Yechiel Mikhel Epstein, author of the highly influential Arukh Ha-Shulchan, published an article in a 1903 Torah journal arguing that lights may be turned on and off on Yom Tov. Part of his calculations was the incorrect scientific understanding (as pointed out by R. Yehudah Borenstein in a rebuttal in that journal) that electric current is fire running through the wires. Another of his arguments was that flipping a switch is considered gerama, indirect action. While gerama is generally forbidden, it is allowed when extinguishing a fire on Yom Tov. In a similar fashion, R. Tzvi Pesach Frank, the Chief Rabbi of Jerusalem, published an article in a 1934 Torah journal arguing that flipping an electrical switch is gerama.

However, the overwhelming consensus of subsequent authorities rejected this approach. In 1935, the young Jerusalem scholar R. Shlomo Zalman Auerbach dared to disagree with the two aforementioned scholars and devoted chapter three of his monumental study, Me’orei Eish, to this issue. He argued at length that flipping a switch is considered direct action, rather than gerama. He obtained for his book a glowing approbation from the eminent authority, R. Chaim Ozer Grodzinski of Vilna. R. Grodzinski also penned a responsum arguing the same, later published as Achiezer vol. 3 no. 60. R. Eliezer Waldenberg, also a young scholar in Jerusalem, after studying R. Auerbach’s book and a copy of R. Grodzinski’s responsum (which he obtained from R. Auerbach), wrote a responsum of his own disagreeing with details of argumentation but agreeing with the conclusion (Tzitz Eliezer vol. 1 no. 8). Others, both before and after, have concurred that flipping a switch is direct action. The reasons offered why impact greatly both the Gerama Switch and the Kosher Switch.

II. Ungerama

Halakhic engineers attempt to avoid issues like gerama through creativity. Examining their proposals and the objections they face will offer us insight into potential objections to the Kosher Switch. The Zomet Institute bases its solutions on the concept of modulating currents. This interesting but controversial approach is irrelevant to our current discussion. The Institute for Halacha and Science developed a Gerama Switch based on the concept of obstruction removal (meni’as meni’a) that serves as a basis of the Kosher Switch. There is a certain amount of rivalry between the institutions which I do not fully understand. I suspect that I may be oversimplifying the distinctions between their approaches but this should suffice for our purposes. However, both work with the assumption that turning electricity on and off is forbidden on Shabbos. Their goal is to find workable solutions by avoiding the user’s closing and opening circuits.

The Gerama Switch is poorly named because it is designed to avoid gerama. The switch contains an optical signal that closes or opens a circuit through an impulse light sent at random intervals. If the light is received, the circuit closes and if not it is opened. The switch, in the off position, blocks the impulse light and prevents the circuit from closing. By moving the switch to the on position, you merely stop preventing the circuit from closing. You are neither directly nor indirectly closing the circuit, just removing the obstruction. Because this is not even gerama, moving the switch should be permissible on Shabbos even to perform an act indisputably prohibited.

Why isn’t this gerama? Conflicting passages in the Talmud describe gerama as either permitted or forbidden. Placing bottles of water to break when hit by fire, thereby extinguishing the fire, is permitted. Tossing grain into the air so the wind separates the wheat from the chaff is prohibited. Some early authorities forbid all gerama except where explicitly permitted and others permit it except where explicitly forbidden. The Rema codifies what is essentially a compromise position: we forbid gerama on Shabbos except in cases of great need (Shulchan Arukh, Orach Chaim 334:22). However, he does not define the boundaries of gerama, leaving the task for later authorities.

There are four main theories explaining the difference between permitted and forbidden indirect actions (R. Dovid Miller explains these views nicely in a lecture: link).

  1. A time delay between a person’s action and the subsequent action makes the first permissible
  2. If the second action will not definitely occur then the first is allowed
  3. If this is not the normal way of performing the act then it is permitted
  4. If the second action is not already in motion then the first is allowed

The Gerama Switch does not rely on the rejected views of R. Epstein and R. Frank, because its user only removes an obstruction. It also entails a time delay, until the next light impulse. However, this is only permissible according to the first approach to gerama. According to the other three, it is still forbidden. For another important reason, which we will discuss later, the designers of the Gerama Switch only allow it in exigent circumstances — for the needs of the infirm and security reasons — when the Rema would allow gerama.

III. Kosher Ungerama

The Kosher Switch adds uncertainty to the Gerama Switch. Every time the device is supposed to send a light impulse, it calculates a random number below 100 and only sends the impulse if the number passes a threshold (usually over 50). The receiver also calculates a similar random number and only receives the light impulse if the number passes a threshold. These two levels of uncertainty separate the action of moving the switch to the on (or off) position from the closing (or opening) of the circuit. The first impulse may not change the circuit, and the second and third may not as well. There is a statistical possibility, albeit remote, that the person may have to wait days or even months until the light impulse is sent and received.

This improvement to the Gerama switch is an important step forward. It renders the device permissible also according to those authorities who follow the second approach above. However, those who follow the third and fourth still do not allow it. This is particularly significant because those authorities are highly influential.

IV. Not So Kosher

R. Joseph B. Soloveitchik, as reported by R. Hershel Schachter (Nefesh Ha-Rav, p. 169), follows the fourth approach. See also R. Schachter’s Be-Ikvei Ha-Tzon, ch. 7 (“Ma’aseh U-Gerama Bi-Melekhes Shabbos“). Because the Kosher Switch functions constantly, waiting for the switch to be moved so it can close the circuit, R. Soloveitchik would presumably forbid its use.

R. Chaim Ozer Grodzinski (ibid.) follows the third approach, as does the Tzitz Eliezer (ibid.) based on the Eglei Tal (zoreh n. 4). So do R. Yechezkel Abramsky (Chazon Yechezkel, Shabbos 120b) and R. Nachum Rabinovich (Si’ach Nachum, no. 25). R. Yosef Shalom Elyashiv also reportedly follows this approach (Shevus Yitzchak, p. 138; Orechos Shabbos, vol. 3 ch. 29 n. 52). See also R. Nissim Karelitz, Chut Shani, vol. 1 p. 206.

Because flipping a switch is the normal way of closing a circuit (e.g. turning on a light), these authorities would not allow any type of Gerama or Kosher Switch. If this switch becomes widely adopted, as its designers hope, then it will be the standard way of closing and opening circuits, turning lights on and off. This is precisely the situation that R. Grodzinski and the others forbade.

R. Shlomo Zalman Auerbach clearly followed this third approach in his Me’orei Eish, quoting R. Isser Zalman Meltzer on the matter (Me’orei Eish Ha-Shalem, p. 217). He restated it in an early responsum on milking cows on Shabbos (ibid., p. 612ff.) and a later responsum on telephones (Minchas Shlomo, no. 9; Me’orei Eish Ha-Shalem, p. 576). A manuscript was posthumously published in a memorial book for R. Auerbach, Kovetz Ateres Shlomo, which seems to contradict this approach but his son, R. Shmuel Auerbach, insists that his father maintained his original attitude (Orechos Shabbos vol. 3 ch. 29 n. 52).

However, Prof. Zev Lev (Ma’arkhei Lev, p. 241) reports an important ruling from R. Shlomo Zalman Auerbach. R. Auerbach ruled that if an action is performed in a specific way only on Shabbos, that does not constitute the normal way the action is done. The Kosher Switch has a weekday mode and a Shabbos mode, which function differently. According to this ruling of R. Auerbach, turning lights on with the switch in Shabbos mode is not the normal way of turning on the lights and is therefore permissible.

I find this difficult to understand. This is a switch that is designed to work this way, functions the same way as other switches (from the user’s perspective), and performs in the same way once a week plus holidays. I make no claim to expertise but that seems to me to be the normal way the action is done. From what I have seen in the name of R. Elyashiv, he disagrees with R. Auerbach’s ruling and forbids all types of Gerama (or Ungerama) devices. I think this aspect of the issue requires further elaboration and evaluation by halakhic decisors.

V. Publicity and Endorsements

The Kosher Switch has reportedly received numerous rabbinic endorsements (link), including from R. Yehoshua Neuwirth, R. Nachum Rabinovich, R. Moshe Sternbuch and R. Yisroel Belsky. It is not clear, however, whether those endorsement are for use in exigent circumstances or in every home. I suspect it is the former, particularly given R. Rabinovich’s strict ruling on electric switches (Si’ach Nachum, no. 25).

However, the device’s promoters claim that it is appropriate for every home. Indeed, in their halakhic defense of the innovation (link – PDF, sec. 12), they claim that the device will eventually become standard in all homes, thereby enabling universal Shabbos observance and the arrival of the messianic redemption. Are the endorsements also exaggerated PR? I am in the process of checking on some of the endorsements, many of which seem to be just a well-wish rather than explicit approval.

VI. Confusion

The Institute for Science and Halacha, the designers of the Gerama Switch only allow its use in exigent circumstances for the following reason (R. Levi Yitzchak Halperin and R. Dovid Oratz, Shabbat and Electricity, pp. 32-33):

The difference between a gerama switch and a standard switch is not readily discernible to a layman. A person seeing someone using a gerama switch might conclude that the action is permissible with any switch. As a result, people could mistakenly permit many prohibited Shabbat actions, resulting in mass desecration of Shabbat. Under such circumstances, it is appropriate not to permit actions that should otherwise be permitted.

To prevent such misunderstanding, the use of the gerama switch is limited to uses where an ordinary gerama would be permitted, hence the name gerama switch and not meni’at hameni’ah switch… Accordingly, the Institute uses the gerama switch only under those conditions in which ordinary gerama can be permitted.

The designers of Kosher Switch, in their halakhic defense (sec. 7), argue that this is unnecessary for a number of unconvincing reasons. Among them is that the Kosher Switch looks very different from regular switches. I cannot speak for the situation in Israel, but in the US switches come in very different shapes and sizes. I show below five pictures of switches. Four are from my house and one is the Kosher Switch. Can you tell which one is the Kosher Switch? It doesn’t look particularly different to me (note that I cut off the KosherSwitch logo in the image). There are many different types of switches and the Kosher Switch looks to me like just another one. While it carries a Kosher Switch logo, that is hardly sufficient, as the designers of the Gerama Switch acknowledged.

In addition to the issue of confusion, there are other issues that enter this discussion, such as zilusa de-Shabbos, diminishing the Shabbos experience, and shevisah ha-nikeres, resting in a manner different from the rest of the week. I leave that for another time but wish to emphasize that they are also significant Shabbos values.

The Kosher Switch is an important step forward in Shabbos technology and will improve the devices designed for security and health situations. However, I struggle to see how it satisfies the requirements of many important authorities and how it could possibly become a standard feature in Shabbos observant homes.

About Gil Student

Rabbi Gil Student is the Publisher and Editor-in-Chief of TorahMusings.com, a leading website on Orthodox Jewish scholarly subjects, and the Book Editor of the Orthodox Union’s Jewish Action magazine. He writes a popular column on issues of Jewish law and thought featured in newspapers and magazines, including The Jewish Link of New Jersey, The Jewish Echo and The Vues. In the past, he has served as the President of the small Jewish publisher Yashar Books and as the Managing Editor of OU Press. Rabbi Student recently served on the Executive Committee of the Rabbinical Council of America and currently serves as Director of the Halacha Commission of the Rabbinical Alliance of America. He also serves on the Editorial Board of Jewish Action magazine and the Board of OU Press. He has published five English books, the most recent titled Search Engine: Finding Meaning in Jewish Texts, and served as the American editor for Morasha Kehillat Yaakov: Essays in Honour of Chief Rabbi Lord Jonathan Sacks.


  1. MiMedinat HaYam

    R. Moshe Feinstein, in Iggeros Moshe, basically opposes time clocks on shabbat, basically for reasons similar to what you cite above (i beleive he also uses the term ‘zilzul’), allowing it for limited reasons like ‘tzorchei tzibbur.’

    However, it seemr his opinion is not really followed today, as can be seen by the proliferation of ‘shabbat clocks’ nowadays.

    • Do you mean that R. Moshe Feinstein considers it not just not-gerama but actually performing the melachah itself? Where does he say that?

    • RMF invokes mar’is ayin, which means that once they became commonplace, Rav Moshe’s objection to using timers for appliances on Shabbos disappears.

      That’s different than zilzul or gerama, the issues being raised here. One might add mar’is ayin to the mix — people might thing you’re flipping a regular switch. If they then think it’s okay to use regular switches, that would technically mar’is ayin. If they then think you’re a sinner for using a switch on Shabbos, that’s technically cheshad which is a different motive for legislation, but it’s often called mar’is ayin anyway.

  2. MiMedinat HaYam

    I’m not in my office today (no computer access) but google sent me to https://www.torahmusings.com/2010/09/timers-on-shabbat-and-yom-tov which discusses related issues not necessarily in the context of ‘grama’.

  3. Hi, Just wondering why this has been reposted when the kosher switch site has a page disproving these points?

  4. Do they spell out anywhere exactly how their technology is different from Machon Zomet’s in a way that justifies saying that even though Zomet’s switch is gerama (rabbinically prohibited in most circumstances as an indirect violation of a melakhah) theirs isn’t?

    I looked at the patent application, and I can’t figure out how it differs. I assume there is some difference, whether halachically relevant or not (which someone else can decide). I would think the Israeli patent office would know to check Zomet for “prior art”, so the granting of their patent implies they’re doing something unique. But I can’t find it spelled out on their site.

  5. In all likelihood, the Zomet one doesn’t have the light on a randomized timer (with indicators), nor the randomized chance for the light pulse to operate the switch.

    • But they do have a randomizer on the LED whose light you may or may not block. As do Shabbos mode ovens.

      The Kosher Switch has a the same randomizer on the detector opposite the LED, but I don’t see how that makes anything more random.

      But now that you had me looking at their “How it Works” page, the key difference has the description of a sefeiq sefeiqa. It’s far from clear what is meant. Here’s the quote:

      This creates two safeiks (Halachic uncertainty): the first, whether or not the light pulse of the Light Pulse Pair will fail; the second, whether the switch will fail in triggering the circuit based on the results of the Light Pulse Pair.

      “The switch will fail in triggering the circuit”? What are they doing to introduce this second safeiq?

      Also, in what sense is either a safeiq? Both will eventually happen, the question is when. I am not sure how “sefeiq sefeiqa” applies. But at least I’m a step further in my understanding.

      PS: On the relevance of randomness to gerama…

      AhS OC 514:11 (still catching up to the yomi schedule after Pesach) quotes the Rama (se’if 3) who in turn cites the Maharil that it’s permissable to put a candle in a windy place on Yom Tov that it should be blown out, as long as the wind isn’t blowing at the time you’re taking it outside. The AhS explains, “For doing so before the wind comes — that is geram kibui”.

      A case of gerama with a random time delay. But this is Yom Tov, where the laws against extinguishing are looser. The AhS refers you to OC 277:7, where we see that on Shabbos it’s assur — but because of a special gezeira to prevent people from doing the same when the wind is blowing. Not because of gerama.

      I also don’t think the randomness of the length of the delay is necessarily relevant. Just pointing out halachic precedent.

      But it’s certainly not “iffy” that we could invoke sefeiq sefeiqa. It’s a random length delay, not a doubt whether or not the switch will eventually cause the outcome. The odds the wind will never come, or the randomizer(s) will never produce a combination that causes the switch to be honored, is ignorably small. (No one is selling a switch that may or may not shut the light.)

      • “But they do have a randomizer on the LED whose light you may or may not block. As do Shabbos mode ovens.
        The Kosher Switch has a the same randomizer on the detector opposite the LED, but I don’t see how that makes anything more random.”

        So my guess that there is a physical difference between the two switches (and even the approximate place in the design) is correct.

        As to why that makes an halachic difference you would be best served asking the KosherSwitch company.

  6. So I am not intending to offend or anything, and I am new to this, trying to make up my mind. I’m just wondering why you cropped out the bottom of the kosherswitch in your picture of it, especially when you are talking about how it is indistinguishable from other light switches. If you showed the rest of the light switch, you would see the logo and the flap that comes down, sabbath mode etc. Just wondering why you chose not to show that part of the switch. Thanks!

    • There are two separate issues – is this switch like other switches? does a sign or logo make a difference? If I included the logo, you would not be able to answer the first question.

  7. This may or may not matter to some of the commenters, but the switch is meant to be installed in place of a regular switch, so that on shabbos you use it in shabbos mode (indicator green) and on chol in chol mode (indicator red). And the internal workings are very similar–in chol mode the light pulses are quick and regular, and in shabbos mode they are randomized as to frequency and the other parameters mentioned. So even during the week one is basically doing a hasoras hamonei’ah. This seems to diminish the differentiation aspect between chol and shabbos methods of accomplishing the task.

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