Eruvs

Life is a lot simpler for north west London's Orthodox Jewish Community since the creation of Britain's biggest eruv in February 2003.

The eruv has a boundary 11 miles long and encloses an area of 6.5 square miles. It covers Hendon, Golders Green and Hampstead Garden Suburb, together with parts of Childs Hill, Cricklewood, East Finchley, Finchley and Mill Hill.

What is an Eruv?

An eruv is an area within which observant Jews can carry or push objects on the Sabbath, (which lasts from sunset on Friday to sunset on Saturday), without violating a Jewish law that prohibits carrying anything except within the home. There are over 200 eruvs (or eruvim) in the world.

An eruv must be 'completely enclosed'. The area is not enclosed by building a special wall round it - most of it is enclosed by existing natural boundaries like railway lines or walls. What matters is that the area is completely enclosed by boundaries that conform to Jewish law. The North West London eruv has been recognised as valid by the London Beth Din - the Orthodox Jewish religious court.

What does an eruv allow people to do?

An eruv mixes the boundary between the area within the home and the area outside it. The result is that within an eruv Orthodox Jews can follow the same rules on the Sabbath that they would in their homes.

Jewish law says that Jews must not carry any item, no matter how small or for whatever purpose in a Reshus HaRabim (public domain - outside their home) on the Sabbath, even if they are allowed to carry them within their home.

Pushing things is also forbidden - so families with small children (who would use prams and pushchairs) or the physically disabled (who would use wheelchairs) are effectively housebound. They can't even go to the synagogue to fulfil their religious duties on the Sabbath.

But both carrying and pushing are allowed inside an eruv because it's regarded as within the home domain. So in an eruv Jews can:

• carry house keys (but not car or office keys)
• carry a handkerchief
• carry food or drink for use during the Sabbath
• carry prayer shawls
• carry books - normally a Jew can't even carry a prayer book on the Sabbath
• carry essential medicines - for example a diabetic Jew can now carry their insulin with them
• carry extra clothes such as a raincoat
• carry nappies
• carry reading glasses
• push a pram or wheelchair
• use a walking frame or crutches

An eruv therefore makes it easier for Jews to follow the spirit of the Sabbath by making it enjoyable and fulfilling, without breaking the rules that keep it holy.

What doesn't an eruv allow?

An eruv doesn't permit Orthodox Jews to carry things that cannot be moved at all on the Sabbath, such as mobile phones or pens or wallets, or carry things for use after the Sabbath.

Nor does an eruv permit Jews to do things that break the spirit of the Sabbath - such as going shopping or swimming, riding a bicycle or playing football in the park, or gardening.

How is an eruv made?

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.