The Halachic Form of a Tzuras Hapesach

Tzuras hapesach means the form of an entrance. It is not a symbolic string and it is not defined merely by having a wire somewhere above a street. Halacha gives the doorway a particular form: two vertical sideposts and an upper member positioned over them.

That simple definition is the starting point for understanding the poles and wires used in many city eruvin. The parts do not need to look like a conventional wooden doorframe, but they must stand in the halachic relationship of doorposts and a lintel.

Two uprights and a member above them

The Shulchan Aruch, Orach Chaim 362:11, defines tzuras hapesach in seven words:

קנה מכאן וקנה מכאן וקנה על גביהן

There is a vertical member on one side, another on the other side, and an upper member above them.

The Alter Rebbe gives the same definition in Orach Chaim 362:20 and then spells out the consequences. The two sideposts must be at least ten tefachim high. The upper member may be far above them and need not physically touch them. What makes the arrangement a doorway is the relationship between the vertical members and the member above.

This is why the familiar urban form can consist of relatively short sideposts below a wire that is much higher. The empty air between a sidepost and the wire is not, by itself, a defect. The critical question is whether the vertical member is directly beneath the upper one.

Directly under the upper member

The Alter Rebbe requires the sideposts to be "מכוונים כנגד קנה העליון", aligned with the upper member. He then states that if they are displaced from that line even by a small amount, the tzuras hapesach is invalid, because it no longer resembles an entrance.

The geometry is therefore vertical. One does not ask only whether a pole is close to a wire. One asks whether the line of the wire passes over the valid sidepost. A utility pole can stand beside a wire without serving as the doorpost for that wire. Conversely, an upright may be far below the wire and still satisfy this part of the requirement when it is correctly aligned beneath it.

The same principle applies at both sides of the opening. The upper member must correspond to the two uprights that define the entrance. If the intended uprights are not under that line, the mere presence of nearby poles does not create the required form.

Above the posts, not attached to their sides

The Shulchan Aruch also rules that the upper member does not qualify when it is attached to the side of a post rather than positioned above it. The Alter Rebbe explains the reason: a lintel of an entrance is over its doorposts.

This rule is easy to confuse with the separate rule that the upper member need not physically touch the sideposts. Contact is not required. Position is required. A wire suspended several feet above a post can satisfy the over and under relationship, while a wire fastened directly into the side of a post can fail it.

The Alter Rebbe records a narrower discussion where a rope is wrapped around the very top of the upright and nothing projects above it. He cites an opinion that such a form is valid, but writes that it is proper to be stringent and place the rope on the actual top of the posts. This detail does not change the basic rule. Tzuras hapesach is formed by an upper member over sideposts, not by a line running into their sides.

The sideposts need substance; the upper member may be light

The two parts of the doorway do not have identical strength requirements.

The sideposts must be strong enough to support some kind of door, even a very light one made from straw or reeds. They are the halachic doorposts and therefore cannot be merely imaginary points beneath a wire. The Alter Rebbe states this requirement directly in Orach Chaim 362:21.

The upper member is different. It may be extremely light. The Shulchan Aruch and the Alter Rebbe both allow even a very slight material to serve above the posts. This is one reason a cord or wire can serve as the upper member of tzuras hapesach when the rest of the form is valid.

The fact that the upper member may be light does not remove the general need for a real, identifiable construction. The validity of a particular wire, attachment, pole, or other object depends on how it functions in the actual doorway form.

Ten tefachim of vertical sidepost

Each sidepost must rise at least ten tefachim. That measurement belongs to the general halachic concept of a mechitza and appears explicitly in the laws of tzuras hapesach.

The upper wire may be much higher than ten tefachim. There is no requirement that the sidepost physically extend all the way to it. Thus, the minimum height of the sidepost and the height of the upper member are two separate questions. A short but halachically sufficient upright can stand below a high wire, provided the required alignment exists.

This rule should not be turned around. A wire at a great height does not create sideposts beneath itself. Valid uprights still have to exist on the two sides of the opening.

One doorway after another

A city enclosure can be composed of many valid sections. An actual wall may end where a tzuras hapesach begins, and one doorway form may be followed by another. The fact that the materials change does not necessarily break the perimeter. The issue is whether the halachic enclosure continues from one valid element to the next.

For a series of tzuras hapesach sections, each opening has to retain the required doorway form. At turns, intersections, or places where one wire ends and another begins, the relationship among the uprights and upper members must still leave a valid continuation. A route that looks connected on a map can nevertheless contain a halachic break if one of those transitions does not qualify.

The practical rules governing poles, wires, corners, and street openings apply these principles to urban construction. Those details should not be confused with the definition itself.

Width and the laws of breaches

A tzuras hapesach can do more than mark a narrow doorway. The Alter Rebbe rules in Orach Chaim 362:19 that, according to the primary view, it can close even an opening wider than ten amos. He applies that rule in a residential courtyard or mavoy, and records circumstances in which even all four sides may be formed by tzuras hapesach.

He also records a stricter view. According to that opinion, tzuras hapesach does not repair an opening wider than ten amos in the same broad manner unless the required relationship between the closed and open portions, or another specified condition, is present. The Alter Rebbe writes that it is proper to take this stricter opinion into account, even though the primary halacha follows the first view.

Accordingly, the validity of the doorway form itself does not answer every question about the enclosure. The size of openings, parutz and omed, and the kind of area being enclosed have their own halachos. Those rules are treated under walls, gaps, and omed merube.

Tzuras hapesach and a reshus harabim

There is a further limit when the area is a complete reshus harabim.

In Orach Chaim 364:4, the Alter Rebbe explains that tzuras hapesach has the status of a complete partition on the Torah level, even when erected in a complete reshus harabim. He nevertheless rules that Rabbinically tzuras hapesach alone is not effective to permit carrying in such a reshus harabim. For that, he requires delasos, actual gates, and then discusses the conditions governing their closing.

This distinction is essential. Whether two posts and a wire form a technically valid tzuras hapesach is one question. Whether tzuras hapesach is sufficient for the domain being enclosed is another. A city eruv cannot be decided from the appearance of the poles and wires without first addressing the halachic status of the streets and the other requirements of the enclosure.

The separate laws of gates and delasos in a large city continue that subject.