Eruv Halachic Principles | Toronto Eruv

Eruv Halachic Principles


In order to better appreciate what is involved in the creation of an eruv, and in particular, to understand the issues surrounding the construction and maintenance of the Toronto Eruv, we would like to set out a brief summary of the main halachos governing the prohibition of carrying ( ) on Shabbos.

For the purposes of carrying on Shabbos, there are four different domains ( ), each with different rules.

1. “Reshus Harabim” or a public domain, is generally described as a public thoroughfare at least 16 amos wide. There are many intricacies involved with the qualifications of an area as a reshus harabim and these will be discussed below.

2. “Reshus Hayachid” is a private domain which contains an area of at least four tefachim by four tefachim and is generally surrounded by enclosures at least 10 tefachim high. The enclosures can take a variety of different forms.

3. “Carmelis” is a quasi-public domain which does not have the attributes of a reshus harabim as prescribed by the Torah. A carmelis is usually described as an area of at least four tefachim by four tefachim which is not enclosed in a manner that would otherwise render it a reshus hayachid.

4. “Mekom P’tur” is an area which, because of its small size or location, does not fall into any of the categories set out above.

The biblical prohibition of carrying on Shabbos consists of carrying an object between a reshus hayachid and a reshus harabim or carrying an object across a reshus harabim for a distance of four amos.

The chachamim added on a number of prohibitions to prevent an individual from accidentally violating a biblical prohibition. Thus, one cannot carry within a carmelis for a distance of four amos, between a carrnelis and a reshus harabim or between a carmelis and a reshus hayachid. One may also not carry within a reshus hayachid like a courtyard which is accessible to more than one individual or family (e.g. a courtyard) without making an eruv chatzros.

The goal in creating a proper eruv is to render the entire area within the eruv into a reshus hayachid by way of walls or enclosures. In addition, it is necessary to make an eruv chazeiros and acquire the license to use the city streets for the purpose of the eruv from municipal authorities.

The halochos discussed on these pages summarize some of the major principles of hilchos eruvin. It is not intended as a definitive source to resolve issues. If the reader has any specific questions, he is asked to consult his Rov.

Reshus Harabim

The most difficult issue relating to an eruv in a large metropolitan area is whether the area of the eruv includes a reshus harabim for the biblical interpretation. As stated above, a reshus harabim is an uncovered public thoroughfare at least 16 amos wide. Others include requirements such as that it must be a thoroughfare which is open at both ends ( ), straight, and accessible to the public day and night.

As a practical matter, it is very difficult, and sometimes impossible to build a kosher cmv around a true reshus harabim. This is because the public’s passage through the eruv’s enclosures can be deemed to negate or “break down” the walls of the enclosure ( ). Chazal tell us that the solution to this issue is to install operable doors, (and according to some poskim. ones which are actually closed nightly), at the entrance points to the reshus harabim. In fact, the gemara says that this was done in Yerushalayim.

There is a dispute among the poskim as to whether a reshus harabim requires at least 600,000 people. According to those poskim who follow Rashi’s view that 600,000 people are required, a true reshus harabim is very rare and is only found in the largest and densest of cities.

There is a great deal of discussion in how one measures or counts the population requirements of a reshus harabim. Is it sufficient if 600,000 people reside in the city or must they actually pass through the street? Do transient visitors from surrounding areas count? Do you count the people on a single street or those dispersed across the city? Do you count people passing during the course of a day or at a given moment in time? Do people in cars or passing trains count? If a single street qualifies as a reshus harabim, do all the other streets in town which connect to it also become a reshus harabim?

The issues are many. However, on a practical basis, Harav Moshe Feinstein zt’l qualified a reshus harabim according to these poskim as an area where at least 3,000,000 people reside in an area measuring 12 milby 12 mil(144 square mils. A mil is 2000 amos). This is based on his estimate of the total population of Machne Yisroel in the midbar and on his conclusion that 600,000 people would be found in public areas over the course of a day. The population of Toronto within the eruv boundaries does not meet this criteria.

The Rambam and some other leading poskim do not require 600,000 people in order to qualify an area as a reshus harabim. According to these poskim, of course, it is far more difficult to make an eruv in a large city.

There is a long list of poskim who subscribe to each of these views. The practice in Europe to build eruvim followed the general minhag in Klal Yisroel to rely on Rashi’s position. However, because of the wide support received by the Rambam as well, the Mishne Brura suggests that a “Baal Nefesh” (i.e. someone who wishes to set a loftier standard for himself) should be machmir.

For those who wish to follow the Rambam, it is necessary to create an eruv with at least three sides which have a majority of their length enclosed with actual walls (‘ ). This deems the entire area so surrounded a reshus hayachid, even in circumstances where the public passes through gaps in the enclosure. To complete the eruv, it is then required to close the gaps with tzuros hapesachs as described below. As will be seen, this is the approach taken with respect to the Toronto Eruv.

A particular problem raised by the rules of reshus harabim is the effect of Highway 401 on the Eruv, since this highway has more than 600,000 persons traveling on it each day. Moreover, there are many poskim who hold that an intercity thoroughfare is intrinsically a reshus harabim even if 600,000 people do not travel on it each day. Although there are walls which run along both sides of the highway, it is impossible, for obvious reasons, to bridge the walls across the width of the highway. Accordingly, the entire area of highway 401 had to be stripped out of the eruv. More will be said about this later.


As stated above, it is prohibited to carry from a reshus hayachid to a carmelis, or within a carmelis. Most Toronto streets are considered a carmelis. Therefore, the goal of the eruv is to halachically enclose the perimeters of the Jewish areas of Toronto in order to deem the entire area within its boundaries, a reshus hayachid.

Halachically, a reshus hayachid can be “fenced” with either actual fences or with a rnn rrn (“tsuras hapesach”), which is essentially a horizontal element such as a lintel set on top of two posts (“lechayayim”), to create the appearance of a doorway. Halachically, the area enclosed by the tsuras hapesach is considered to be closed. As a practical matter, most eruvim have substantial areas enclosed by tsuros hapesach, typically a telephone wire running on top of telephone poles. There are, however, many practical difficulties in building an eruv of tsuros hapesach enclosures over large areas.

The horizontal element must be located precisely on top of the pole and not on its side. Halachically, it is sufficient for the vertical element (the “lechi”) to have the minimum height of 10 tefachim on a vertical plane even if it does not physically reach the horizontal element. However, the horizontal element must be precisely within the projection of this vertical plane. This is the result of the principle of “gud asik”. Gud asik deems a pole, once it meets the minimum halachic requirement of 10 tefachim, to project upwards on an absolute vertical plane.

Accordingly, using a telephone wire as an example, the wire must be precisely on top of the pole and if that were not the case, another vertical element of at least 10 tefachim must be attached at a spot precisely below the path of the wire. Even one improperly constructed tzuras hapesach can invalidate the entire eruv.

Generally, a tzuras hapesach is not considered as good a mechitza as an actual fence because of all the physical and halachic issues pertaining to it. Thus, for practical considerations, it is better to create a reshus hayachid with actual fences.

As stated above, in order for a wall to be ‘omed meruvah al haporetz’, and not be subject to the problem of the public’s passage negating the mechitza, it is necessary to have actual fences running along most of its length. At least three sides of the eruv need to meet this requirement in order to enclose a reshus harabim properly.

Fences can be built from different types of materials as long as they are at least 10 tefachim high and have a specified degree of impermiability. Typically, fences are made of wooden or chicken wire fencing or the “seven strand” farm fences which is often seen running along the railways.

An area can also be considered fenced by a natural slope. This is another manifestation of the principle of gud asik. Thus, the edge of a cliff is deemed to project upwards. In order to qualify as a “fence” for the purpose of an eruv, the slope must run at least 10 tefachim vertically within a maximum of four amos horizontally. This works out to about a 24 degree slope. A natural slope can occur on a hillside or even beneath the surface of a body of water. The original Toronto eruv relied, to a large extent, on slopes beneath Lake Ontario, as well as beneath the Don River.

An eruv cannot have gaps in excess of 10 amos. For other reasons which will be discussed below, it is preferable to avoid gaps which are even 4 tefachim wide. As you can imagine, it was a massive effort on the part of the committee to create an eruv which runs for approximately 40 kilometers, and ensure that no such gaps occurred along its entire length. As a practical matter, in the event one wishes to rely on a slope beneath the surface of the water, it would be necessary to ensure that the grade of the slope and its proper dimensions are maintained continuously with no such gaps beneath the surface.

‘Pi Tikra Yored V’Sotem’ is another technique used to create a mechitza, Imagine a canopy in front of a house. If the canopy has a vertical edge of at least one tefach, the edge is deemed to project down to the floor. This principle has application to highway underpasses or areas below elevated traintracks. Halchically, we may only rely on this technique if two of the other walls of the enclosure actually meet. There is also some doubt about the application of the rule where the vertical structure was constructed for a purpose related to the top of it (i.e. an elevated railway line) as opposed to protecting what is underneath.

Eruvei Chazeiros

The chachamim have decreed that it is not permitted to carry, even in a reshus hayachid, if it is accessible to more than one individual home. This is in order to prevent confusion between a reshus harabim and a reshus hayachid, which looks like a public domain because it is used by a number of people.

The rabbinically endorsed method of resolving this issue is by the creation of an Eruv Chazeiros which halachically “blends” the various reshus hayachids together. In the event the eruv chazeiros includes areas where people other than observant Jews who respect the halachos of eruv reside, it is necessary to obtain a municipal license to use the streets for the purpose of the eruv.

The classical case described numerous times throughout the gemara is that of a courtyard or “chatzer” which connects two or more individual houses. Two or more chatzeiros connect to a “movui” or an alleyway. The alley, which, if properly enclosed, is itself intrinsically a reshus hayachid m ‘doreisa connects to a reshus harabim. In order to carry in such a chatzer, one makes an eruv chatzeiros. To carry in such a movui, one makes a shtufei muvoous. Practically, both procedures are quite similar. However, while the mechitzos of a chatzer can accommodate a gap of up to 10 amos, the mechitzos of a movui may be invalidated with even a gap as small as four tefachim.

Eruvim in Large Urban Areas

There has also been much debate in the Poskim about the appropriateness of creating an cmv around large metropolitan areas. For most of our history, Jewish generally located in smaller communities or areas where the various halachic issues could be more easily accommodated. With the migration of large Jewish populations into major metropolitan areas, a debate arose among the Poskim, whether it is appropriate to create an eruv over large areas with great populations and the associated problems of maintaining an eruv with long perimeters.

Ray Moshe Feinstein zt’l who is considered the foremost posek in modem times resisted the establishment of an eruv in Manhattan. He argued that, besides the halachic issues involved, people who come from areas which could not make eruvim for technical reasons would carry because they would forget entirely about the problems of carrying on Shabbos.

Aside from the halachic issue of reshus harabim, given the severity of transgressing the Shabbos and the practical difficulties of building, maintaining and ensuring people are aware of the kashrus of the eruv on a weekly basis, building an urban eruv is a daunting task.

On the other hand, the making of an eruv is a big mitzvah because a proper eruv saves people from violating Hilchos Shabbos and enhances Oneg Shabbos especially for people with small children or other needs which require them to carry on Shabbos. Many Poskim actually made it incumbent upon the local Ray to ensure that there is a proper eruv in his community. These sometimes conflicting imperatives have generated much controversy and debate.

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