The Alter Rebbe's Eruv and the Halachos of a City Eruv
The Alter Rebbe treats establishing an eruv as a mitzvah while defining closely the conditions that make an enclosure valid.
Reshus harabim and shishim ribo
Shulchan Aruch HaRav records the view that reshus harabim requires shishim ribo and also brings the stricter position that does not make six hundred thousand essential.
Both remain part of the city-eruv analysis. A Rav must decide how they are treated before knowing whether ordinary tzuras hapesach can enclose the streets before him.
Walls, breaches, and tzuras hapesach
The Alter Rebbe distinguishes a valid form of doorway from an ordinary wire and sets out the laws of walls, standing portions, breaches, and openings. Measurements and alignment matter because the enclosure changes the domain in which carrying takes place.
A strong section of wall cannot repair an unrelated open side, and shared food cannot close a physical gap. The route must work as a whole.
Eruv chatzeiros completes the communal joining
After the area is physically enclosed, eruv chatzeiros or shitufei mevo'os joins the participating residents. Sechiras reshus may also be required for domains not included through the ordinary joining.
These arrangements are essential, but they operate inside a valid enclosure. They do not change the status of a reshus harabim or supply missing walls.
The mitzvah depends on validity
The positive value of eruv is fulfilled through the same halachos that make it reliable for carrying. The public should be able to trust that the route, communal arrangements, and supervision are all in place.
Where those conditions have not been met, calling the project a mitzvah does not permit hotza'ah. Accuracy is part of the protection the mitzvah is meant to provide.