Mi Yodeya is a question and answer site for those who base their lives on Jewish law and tradition and anyone interested in learning more. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

A fundamental element of an eruv is the tzuras hapesach, which is defined here as, "[a] doorway opening. The construction of two doorposts and an overhead lintel." Can one make a tzuras hapesach arched or does it have to be straight?

I know there are many authorities who discuss the lechi (post) and korah (crossbeam) being straight, but many doorways have an archway; does anyone discuss whether designing a tzuras hapesach this way would be valid?

share|improve this question
up vote 6 down vote accepted

Indeed, as SethJ and ShmuelBrin noted in their comments, the Gemara (Eruvin 11b) discusses such a case. Shulchan Aruch (Orach Chaim 362:12) summarizes it thus:

כיפה, אם יש ברגליה דהיינו קודם שהתחיל להתעגל י' טפחים, מותרת משום צורת פתח

"An archway, if its legs - before it begins to curve - are at least ten tefachim tall, then it is permissible as a tzuras hapesach."

(The point that emerges from the Gemara there is not that the curve is considered as if it were straight, but that we ignore the curved part altogether, and consider the top of the tzuras hapesach to be the horizontal line tangent to it - the top and the sides don't have to touch, so long as they are aligned correctly.)

share|improve this answer

The answer I think is no. But there are halachic considerations like lovud and 'chavut' which in certain circumstances consider curved things straight.

share|improve this answer
But it looks like a pesach – sam Apr 21 '13 at 17:16
I don't remember which daf, but I recently learned a Gemara in Daf Yomi that suggests to me that Meir is probably correct. Halachah LeMa'aseh, CYLOR, of course, but I'm pretty sure it's a problem. I believe, though, that the Gemara also offers a possible solution, where we imagine it's straight for measuring purposes, but again I don't know the final Halachah. – Seth J Apr 21 '13 at 20:33
@sethj you're thinking of the lechi or of the tzuras hapesach re. Mezuza (chokekim lehashlim)? – Shmuel Brin Apr 22 '13 at 5:18
@Shmuel brin I think you might be right. – Seth J Apr 22 '13 at 12:21

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.