Tzurot HaPetach – A Report from the Field - Part One by Rabbi Chaim Jachter


A surge of interest in community Eiruvin has emerged from Daf Yomi’s recent study of Masechet Eiruvin. Thus, now is an excellent time to share with Kol Torah readers some of my more than 20 years of experience in advising dozens communities about how to construct, expand, and maintain their Eiruvin. We shall focus on the construction of Tzurot HaPetach (symbolic doorframes), which most often constitute the bulk of a community Eiruv. 

Constructing a Tzurat HaPetach seems to be a straightforward process. The Talmud (Eiruvin 11b) states that a Tzurat HaPetach consists of two vertical poles with a horizontal pole directly on top of them (Kaneh MiKan VeKaneh MiKan, VeKaneh Al Gabeihen). However, the laws of a Tzurat HaPetach are actually complex, particularly by a community Eiruv. Community Eiruvin commonly use preexisting structures, which can significantly stabilize an Eiruv and also reduce the costs of building and maintaining an Eiruv. These structures, such as utility poles, were not built for use in Eiruvin and therefore often involve Halachic complexities.

Must the Vertical Poles Extend All the Way to the Horizontal One?

The Talmud (Eiruvin 11b) records a dispute between Rav Nachman and Rav Sheishet whether the vertical poles (Lechis) of a Tzurat HaPetach must extend all the way to the horizontal pole. The Halachah follows the opinion of Rav Nachman, that if the vertical poles are ten Tefachim (approximately forty inches) high and are positioned precisely beneath the horizontal pole, the Tzurat HaPetach is acceptable. The horizontal pole need not touch the vertical poles and may be well above them (Shulchan Aruch, O.C. 362:11). The Mishnah Berurah (362:62) explains that the basis for this ruling is the principle of Gud Asik (literally, ‘stretch up’), which states that the Halachah views the vertical poles as extending upward to the horizontal pole.

The dispute between Rav Nachman and Rav Sheishet might depend upon a fundamental issue – when constructing Tzurot HaPetach, must one replicate an actual doorframe, in which case the Lechis must extend all the way to the horizontal wire, or does Halacha require one to construct only “Mei’ein Tzurot HaPetach” (see Rashi to Eiruvin 11a s.v. UMatach), in which case ten Tefachim high Lechis suffice. Alternatively, even Rav Nachman agrees that a Tzurat HaPetach must replicate an actual doorframe. The point of contention between Rav Nachman and Rav Sheishet is whether the principle of Gud Asik allows us to view a Lechi that does not extend all the way to the horizontal wire as a replication of an actual Tzurat HaPetach.

Gud Asik: Eyesight or Plumbline?

Although Halachah follows the opinion of Rav Nachman that the vertical poles of a Tzurat HaPetach need not touch the horizontal pole (or wire), they must be positioned directly underneath it. The poles cannot even be off by the slightest amount (see Mishnah Berurah 362:63). Halachic authorities debate how to determine the proper positioning. Rav Yosef Dov Soloveitchik (as reported by Rav Yosef Adler) and Rav Moshe Feinstein (reported by Rav Elazar Meyer Teitz, from his uncle, Rav Pesach Rayman) both felt that it is sufficient to estimate the poles' positioning with one's eyes. Rav Zalman Nechemia Goldberg (personal communication) also permits using eyesight, although he requires building very wide vertical beams to allow for a wide margin of error in their positioning. Rav Gedalia Schwartz (personal communication) adopts this approach as well. 

However, Rav Yitzchak Liebes, Rav J. David Bleich, Rav Feivel Cohen, Rav Moshe Heinemann, Rav Hershel Schachter, and Rav Mordechai Willig (all through personal communication) rule that a plumb line (or other device for measuring verticality) is necessary to ensure that everything lines up appropriately. The Gemara (Eiruvin 94b) requires constructing "Halachic walls" (and presumably Tzurot HaPetach as well) in the same manner that people usually build walls (KeDeAvdei Inshei). Builders and carpenters have used plumblines for thousands of years; they are referenced in Amos (7:7-8) and the Mishnah (for example, Kilayim 6:9 and Keilim 29:3). Accordingly, these authorities rule that a plumbline must be used in constructing a Tzurat HaPetach.

 On the other hand, Rav Moshe and Rav Soloveitchik as well as Rav Goldberg and Rav Schwartz could argue that since Halachah does not require the Lechi to extend all the way to the horizontal wire, Halachah does not require a Tzurat HaPetach to replicate an actual doorframe. In which case, an estimate made by eyesight suffices to create a Mei’ein Tzurat HaPetach. Thus, this dispute regarding how to assess “Gud Asik” from the Lechi to the horizontal wire hinges upon the two approaches delineated above as to whether Rav Nachman requires a Tzurat HaPetach to match an actual doorframe.

Rav Shlomo Zalman Auerbach told this author that, while it is best to use a plumbline, one may rely on eyesight alone if it is “impossible” to construct the Eiruv otherwise. When I reported this ruling to Rav Hershel Schachter, his response was that it is always possible to measure “Gud Asik” by a plumbline or equivalent such as a combination of a laser pointer and level. One could respond that a community cannot always readily access someone who is proficient in using a tool that assesses precise verticality. Moreover, laser pointers are easy to use only near dusk and sunrise. Thus, while Rav Schachter’s insight rightfully limits the scope of Rav Shlomo Zalman’s ruling, there are unusual circumstances where it could be relevant, especially when correcting a problem with the Eiruv close to the onset of Shabbat.

A New Machloket?

The issue as to how to assess Gud Asik emerged in the late 1970s and 1980s when Eiruvin began to be built in North America. I discovered this Machloket when I began my involvement in Eiruvin in 1989. I wondered whether the same Machloket had already existed elsewhere. I asked the older Rabbanim who had served communities in pre-war Eastern Europe, how the Eiruvin were built in their communities. Rav David Lifshitz (Rav of Suwalk immediately before World War II) told this author that a plumbline was used when constructing Tzurot HaPetach in Suwalk. Rav Ephraim Oshry (Rav of the Kovno Ghetto) told this author that in Kovno they relied on eyesight alone. Rav Yosef Singer (Rav of Pilzno prior to World War II) also reported that he believes the rabbis he knew in Europe relied on eyesight alone.

Thus, the debate that emerged in the 1970s and 1980s had already raged at least 40 years beforehand. In addition, Rav Meir Goldwicht informed this author that Israeli communities today also have divergent practices regarding this issue. In order to avoid this problem, many communities erect vertical poles that reach the horizontal wire or pole. This method avoids the need to estimate from afar if the pole is directly under the wire.

It is not unusual to discover an issue that began to be debated in one generation had already been debated in earlier generations. For example, Rashi and Rabbeinu Tam dispute the order in which the last two Parashiyot should be placed in Tefilin. Rashi (Menachot 34b s.v. V’hakorei) believes that “Shema” should come before “VeHaya Im Shamo’a,” while Rabbeinu Tam (cited in Tosafot ibid. s.v. V’hakorei) believes that “VeHayah Im Shamo’a” should precede “Shema.” Piskei Tosafot (Menachot 92), in turn, records that, “In Nahardea and Jerusalem, two pairs [of tefilin] were found, one in accordance with Rashi and the other in accordance with Rabbeinu Tam.” Thus, the celebrated Rashi-Rabbeinu Tam debate about Tefilin already raged in earlier generations. Similarly, in twentieth-century archaeologi­cal excavations of the Dead Sea area, both types of Tefilin have been discovered (Encyclopedia Judaica 15:904). Furthermore, the Gemara frequently records disputes between the Amoraim about issues that the Tanaim had debated in earlier generations.

A Sub-Machloket Concerning the “Eyesight Approach”

One could argue that a sub-Machloket exists even within the approach that eyesight suffices to assess Gud Asik. An eyesight assessment involves an estimate of Gud Asik instead of a precise measurement by plumb line. The question is how to make the estimate. Does this approach nonetheless require an “informed estimate” or does even a gross estimate suffice? An informed estimate involves first noticing whether the pole is tilting to the right or left and then estimating Gud Asik from both very near and a longer distance from the site of the proposed Lechi installation.

The question behind this sub-dispute is what suffices to create the “Mei’ein Tzurat HaPetach” – does a gross estimate suffice or is a more thought out estimate required. In other words, since only an approximation of doorframe is required, how much difference between a real doorframe and a Tzurat HaPetach is tolerated. In addition, one could argue that all would agree that a more informed estimate should be made, according to all opinions, when measuring very long distances (such as fifty or even sixty feet) between a Lechi and a very high horizontal wire.

Current Practice

Today (2013) in North America most community Eiruvin extend their Lechis to the horizontal wires, even though the Eiruvin in the 1970s and 1980s commonly utilized only ten Tefachim high Lechis. The change happened to a great extent due to a report by Rav Moshe Heinemann (a leading Halachic authority who is adept with tools, technology and machinery). He reported that he installed ten Tefachim high Lechis on utility poles and measured Gud Asik with a plumb line equivalent. However, when he inspected the Eiruvin a year later he discovered that the Lechis were no longer aligned with the horizontal wire! Rav Heinemann investigated and reported that utility poles shift over time (it is reported that the freezing of the ground over winter causes this shift).

After this discovery Rav Heinemann ruled that Lechis must be extended to the horizontal wire, since proper alignment cannot be maintained on a utility pole. Thus, Rav Sheishet’s opinion has enjoyed a revival when constructing Tzurat HaPetach on contemporary utility poles. An alternative remedy to this problem could be to attach multiple ten Tefachim Lechis on utility poles to create a greater margin of error and to account for the shifting of the pole and wire (such as I saw in Memphis in 1992, where the Eiruv was constructed under the Halachic auspices of Rav Nata Greenblatt). It should be noted, though, that some Rabbanim have expressed skepticism whether concern for pole shifting applies in all areas and especially in more temperate climates such as San Francisco and Vancouver.


Next week we continue with a discussion of some of the hotly debated issues regarding community Eiruvs such as Tachuv and zigzagging wires. 

Tzurot Hapetach – A Report from the Field - Part Two by Rabbi Chaim Jachter

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