What is an Eruv?

An eruv  (עירוב‎ mixture, plural: eruvin) is a ritual enclosure that some communities construct in their neighborhoods as a way to permit the community to carry certain objects outside their own homes on Shabbos and Yom Kippur and to a degree Yom Tov as well.

The eruv allows Jews to, among other things, carry house keys, tissues, medicines, or babies with them, and use strollers and canes. The presence or absence of an eruv thus especially affects the lives of people with limited mobility and those responsible for taking care of babies and young children. In short, it is a community changer.

The eruv however does not allow one to carry Muktzeh (umbrella, electronic devices) or even to carry non-essential items such as extra diapers that are not needed, or any item that is not for Shabbos use but for after Shabbos use.

Indeed, what an Eruv accomplishes is a merger of different domain types into one domain type, making carrying within the area enclosed by the Eruv no different than carrying within a room of a house (i.e. one domain type, namely a private domain), which is of course permitted.

Originally an eruv was essential for a Jewish community to be able to carry water from the town well as well as bring hot food (i.e. cholent) from the central baker’s oven. Today most of our communities find it essential to be able to socially interact with the rest of the community.

The eruv must be made of walls or doorways (Tzuras Hapesach) at least ten tefachim in height, or approximately 1 m (40 inches). In public areas where it is impractical to put up walls, doorways are constructed out of wire and posts. It is these doorways, which often serve no practical purpose, that are what is usually referred to as a Tsuras Hapesach.

If the properties enclosed are owned by more than one person, then all the properties must be combined by the acquisition or rental of some right to the properties, and the designation of a meal that is shared by all property owners. The designation of the meal is called an eruv chatzeiros (combining of courtyards) and it is from this that the term eruv is derived.

One of the requirements of a valid aggregation is that all the parcels must lie within a chatzer, or walled courtyard. For this reason, this type of aggregation is more properly known as an eruv chatzeros (ערוב חצרות‎), an “aggregation of courtyards,” to distinguish it from other types of rabbinically-ordained mixture procedures that also have the name eruv.

Eruv for Carrying

There are 39 categories of activity prohibited on Shabbos. On Shabbos the Halacha prohibits moving an object from one domain to another, no matter its weight or purpose.

Rabbis of the Gemorah cited two sources which refer to this prohibition. “Let no man go out of his place on the seventh day” (Ex. 16:29). This verse is in the context of collecting the Mann bread. The Rabbis said, “Let no man go out of his place with a receptacle in his hand.” According to this, the Mann cannot be collected on Shabbos because it cannot be carried into the  homes.

Second, “So the people were restrained from bringing” (Ex. 36:6). This verse explains that the Jews refrained from bringing further materials for the construction of the Mishkan. The Rabbis explained that this event occurred on Shabbos, not just because no more supplies were needed, but also because the people were not allowed to carry those supplies to the Levi’im camp.

The Rabbis derive the prohibited actions of Shabbos from the actions that were performed to construct the Mishkan.
The Gemorah explains that this prohibition encompasses three actions:

  1. Moving an object from an enclosed area (such as a private home, public building, or fenced-in area) to a major thoroughfare,
  2. Moving an object from a major thoroughfare to an enclosed area, or
  3. Moving an object more than four cubits (Amos) within a major thoroughfare.

To prevent confusion over exactly what constitutes a major thoroughfare, the rabbis expanded the ban to any area that was not fenced or walled in.

The Gemorah, in Maseches Shabbos, says that consistent observance of Shabbos will bring the Moshiach

Checking the Eruv

The boundaries of an eruv must be checked regularly. Our Eruv is checked weekly. In case of inclement weather it is checked more often. If the boundary is not complete and contiguous in every element (i.e., one of the elements of the boundary is missing or broken. Thanks RJ!), no valid eruv can exist that shabbos, and carrying remains prohibited. 
The boundaries of an eruv must be checked regularly. Our Eruv is checked weekly. In case of inclement weather it is checked more often. If the boundary is not complete and contiguous in every element (i.e., one of the elements of the boundary is missing or broken. Thanks RJ!), no valid eruv can exist that shabbos, and carrying remains prohibited. It is imperative to check the Our Eruv app before shabbos to make sure Our Eruv is up.