Talmud Shabbat 18a states that

“It is forbidden to place grain in a water mill [on Erev Shabbat] unless it will be ground before nightfall. Why? Rabba said: Because it creates noise.”[10] Rashi explains: “Because it makes noise and becomes known (avsha milta) on Shabbat, causing denigration [of Shabbat].”

Suppose that a home had a flood on Thursday. The insurance company evaluated the home Friday morning, opened the ceiling and placed giant noisy industrial blowers and fans to dry out the walls and ceiling and prevent mold. The assessor said that these loud units must remain on continuously through Shabbat, and beyond for several days, otherwise mold will build up quickly, and the home will not be insured.

In this situation, may the home owner leave these loud units on during Shabbat?

  • Seems like rfפ. I suggest editing it so it's asking whether the fans can be on independent of reason (i.e. without then very specific case). I move to close this as is. cc @DoubleAA
    – msh210
    Mar 25, 2015 at 21:19
  • @msh210 what's the 3rd word in your comment? I can't eliminate the specific case. That's the specific reason that it's there! Otherwise, what typical person would use industrial fans in his home - esp. ones that make that much noise?
    – DanF
    Mar 26, 2015 at 14:13
  • It's "rfפ".
    – msh210
    Mar 26, 2015 at 14:52
  • @msh210 - OMG ;-) I thought the concept of Yeshivish was disturbing, but now we have Yeshivish "monograms", too?? It may seem like rpk, but the question is more designed to learn how the "noise" rule may work in various circumstances such as these.
    – DanF
    Mar 26, 2015 at 14:58

1 Answer 1


My understanding is that the concern of avsha milta is (at least primarily) the public nature of the (albeit automated) melocho of grinding. In this case, there would seem to be no such problem since air-drying would not seem to be a melocho. (I believe that even according to the Yerushalmi that has a strict and broad interpretation of the melocho of winnowing,it still should only be an issue when something tangible is visibly scattering in the wind).

(In fact, my assumption is that the fans are not necessarily any louder than central air units outside shuls, batei medrash, or other communal buildings that are traditionally run on shabbos.)

  • Good answer! Your assumption of the noise level sounds (no pun, here) credible, though, admittedly, within the confines of a small home, the noise is ... "wadyasay"? If you can source or link your answer, that would be better, though, I assume that you are getting this info from Shabbat 18a. If that's the case, confirm, or just edit in other source(s). Happy Pesach.
    – DanF
    Apr 1, 2015 at 13:44
  • I was working off your quote (and possibly a vague memory of...) Chag kasher v'sameach.
    – Loewian
    Apr 3, 2015 at 4:13

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