Making and using an eruv
How is an eruv made?
Rabbi Jeremy Conway inspects the first post of 86 in the north west London eruv ©
An eruv is created using physical features, like walls and hedges, railway lines and roads, to completely enclose an area of land.
The open spaces between the existing features are filled in by erecting poles with nylon fishing line (or wire) strung in between. The poles and lines are regarded as forming doorways in the boundary - the poles are the sides of the door and the lines are the lintel across the top.
The flimsier parts of the boundary are inspected every week to check that the boundary is intact and that none of the fishing line or poles has fallen down.
Maintaining and checking the North West London eruv costs around £20,000 a year.
How does an eruv work?
In ancient times the rabbis decided that if several houses were built round a closed courtyard, then they could be considered a single giant house, and so things could be carried between them. The continuous boundary of an eruv effectively turns a large area into a sort of imaginary courtyard within which anyone is allowed to carry objects or push prams or wheelchairs; activities which would otherwise be forbidden on the Sabbath.
So an eruv converts an area in which there were once many individual Jewish homes into one big home, shared by one big Jewish family.
There are certain things that may invalidate an eruv:
- It isn't valid if it encloses 600,000 or more people (Jewish or non-Jewish)
- The poles must be reasonably vertical, the lines tight
- Some say the lines must go across the top of the poles (as the lintel of a door goes over the top of the side pieces)
There is nothing to stop non-Jews entering the eruv area either on the Sabbath or during other times.