930. A Wall That is Reduced or Breached

Eiruvin 3:9

Let’s say there is a wall ten handbreadths tall (about 30”) between courtyards and the residents want to tear down part of the wall so that they can make a single eiruv. In such a case, they can make a single eiruv so long as the section they reduce is at least four handbreadths in length (about a foot). If the residents on one side reduce part of the wall on their own side to be lower than ten handbreadths, they may use the shortened section of the wall; the rest of the wall that is still tall is divided between the two courtyards.

Eiruvin 3:10

Let’s say that a tall wall between courtyards is breached. If the breach is no more than ten cubits wide (about 15’), the residents can still elect to make two eiruvs but they may also make a single eiruv because the breach can be considered an entrance. If the breach exceeds ten cubits, the residents may only make a single eiruv and not two separate eiruvs.