A community Eruv is usually a combination of pre-existing structures and whatever additions are needed to connect those structures. The actual components of the eruv may consist of walls, Tzuras HaPesach’s (“doorways” – two side bars with a connecting top bar), and hills.
Below are the basic structural components of a community Eruv:
Eruv walls, which may be made of metal fences, wooden fences, buildings, or cement walls.
Eruv Hill/ Tel HaMislaket, a hill that possesses a specific minimum degree of slope. Hence, Eruv hills may be comprised of rocks, dirt, cement, sand, mud, the edge of a river or lake, or any other ground-like material.
Eruv Doorways/ Tzuras HaPesach are made of two side bars and one top bar. These side and top bars can be made from most materials. Commonly, the top bar is made from telephone lines, string, wire, braided steel, twine, cord, or similar materials. The side bars are often made of metal pole, u-gaurd (a plastic material affixed to utility poles), conduit, wood, or similar materials.
The durability of all these materials plays a significant role in the strength of the Eruv and how often repairs need to be made. Additionally, the way these materials are secured in place plays a significant role in the strength of the Eruv.
If one component of the entire Eruv is broken, 99% of the time the entire Eruv is not usable.
The following are the main factors which could cause an Eruv to become broken.
– Weather Conditions
- Rain – Strings absorb water which can cause them to sag and come out of shape. Rain could also erode a hillside or the ground near a fence or a pole. It might cause the bottom of a pole to grow mold and rust which can cause the pole to break or not be connected to the ground.
- Ice – Ice weighs strings down and could break the string or shift a side bar. Ice also can bring down tree branches.
- Snow– Snow weighs strings down and could break the string.
- Wind- Heavy winds could cause a string to snap or become caught on something near by. Also, the sidebar could be shifted or fall. Weak fences could be shifted by heavy winds.
- Sunlight – Sunlight over time could make the top bar and side bars brittle.
- Heat/Cold– Both heat and cold affect many materials by making the material constrict or expand. For example, if a sidebar constricts, a hole could be created by a screw, thus weakening the sidebar, and potentially breaking it.
– Nature
- Branches– Branches fall on strings, poles, and fences. Additionally, very often, they grow and deflect a top wire out of its correct alignment between the side bars.
- Trees– Falling trees may damage all parts of an Eruv, whether fences, side bars, top bars etc. Sometimes an Eruv is affixed to trees as well.
- Fire– Fire could damage a string directly, or through smoke
- Water (Lake or River)- Water may damage an Eruv, or erode a hillside, or the ground beneath a side bar.
– Human Contact
- Homeless People– These individuals may tamper with fences and doorways.
- Construction sites – Construction crews will remove anything necessary to be moved for construction. This may include components of the Eruv.
- Vandalism – Usable materials of the Eruv may be stolen or broken.
- Incorrect Construction– The Eruv was poorly or incorrectly constructed.
- Children– Children play with anything they find interesting, and may tamper with the components of the Eruv.
- Eruv Construction Worker– While working on the Eruv, a construction worker might pull too hard on one end of a string and unintentionally ruin the other side.
– Vehicular Contact
- Car Accident- When an accident occurs, cars can bump into fences, or side poles and damage them.
- Drunk Driver– A drunk driver may swerve and hit side posts or fences. At times when many people drink alcohol, there have been an increase in broken posts and fences.
- Trucks or Oversized Vehicles – A truck could have something sticking out of it and break the top wire or even a side post. Also, the side mirror of a truck could swipe a side bar which is closer to the road.
– Animal Contact
- Birds– Birds may fly into the top wire and shift it out of shape. If a wire is brittle (from the sun), the wire will easily snap.
- Squirrels– Squirrels may walk on the top wire and break it. Also, squirrels could chew through a wire.