746. A Pole That Just Happens to Be There

Shabbos 17:22

If the pole projects from the wall of the alley, it is still effective. If a pole is just standing by the entrance to the alley and it wasn’t put there in order to enable carrying, it is effective so long as one intends before Shabbos to use it for this purpose on Shabbos. Let’s say that a pole can be seen from the inside of an alley but not from the outside, or vice versa. If it can be seen from the outside but from the inside it appears to be flush with the wall, the pole is effective. If a pole is elevated three handbreadths (about 9”) from the ground, or if it is more than three handbreadths from the wall, it’s like it’s not there at all. A space of less than three handbreadths is acceptable because a gap of three handbreadths is considered closed up. If a pole is very wide - whether it is less than or equal to half the width of the alley - it is valid for use as a pole. If the width is greater than half the width of the alley, it is considered a wall because then the enclosed area on that side of the alley is greater than the open area.

Shabbos 17:23

If a mat is thrown over the beam of an alley’s entrance, the beam no longer enables carrying. This is because the purpose of the beam is to be visually distinguishable and it is no longer visible. If the mat reaches within three handbreadths of the ground, it is considered a wall; if it is three handbreadths or more from the ground, it is not considered a wall. If a person drives two spikes into the front of an alley’s wall and lays a beam across them, he has accomplished nothing. The beam must be placed over the alley, not next to it.