http://revach.net/article.php?id=3218

Section: Halacha   Category: Tshuvos
Rav Moshe Feinstein - Electric Clock And Fan On Shabbos
May you move a fan or clock connected to an electric outlet on Shabbos?  Rav Moshe Feinstein says that if you did not need the clock itself or the place on the clock (Tzorech GufoU'Mikomo ) there is good reason to say it is assur, since its power source is connected to the outlet, even though its intended purpose of telling time or blowing air is not assur.

However if you need to move the fan or clock to use it to blow air in a different direction or to tell the time, you may do so since it is classified a Keili.  If something is a Keili that is intended for forbidden purposes (Kli SheMilachto L'Issur), you may still use it for permissible purposes or just to move it if you need to use the place that it is occupying (Tzorech GufoU'Mikomo ).  Certainly a fan or clock whose main use is for a permissible purpose, even though it is connected to a forbidden power supply, may be moved on Shabbos if you need to use it.

Important Note: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.

This article has not been reviewed by the posek of the AskRevach section, Rav Peretz Moncharsh. Any questions regarding this topic and Halacha L’Maaseh may be asked to him at www.revach.net/ask