The History of the Shabbos Switch

The development of an automated timing device for Shabbos can be traced back as far as the early 1800’s. In the sefer, Masa D’Yerushalayim (Shabbos, Perek 1), the author, Harav Moshe Leib Halevi Litch-Rosenbaum, a disciple of the Chasam Sofer, relates the following.

“I have heard from my rebbe, the great Chasam Sofer, the Talmidei Chachamim of the city of Frankfurt, would study Torah together on Friday nights, staying awake well into the night. Wanting to prepare for themselves some hot coffee, they developed an ingenious contrivance. On Friday afternoon, they would set up a mound of flammable twigs as fuel, douse it with some sulfur as an igniting agent, and place their coffee pot upon it. They would then place a long wick leading up to the coffee pot and ignite the other end of the wick, quite a distance away. It would take about two thirds of the night for the flame to burn across the wick and arrive at the coffee pot. When it would reach the sulfur, the small flame would combust and ignite the twigs beneath the coffee pot, giving them hot, freshly brewed coffee in the pre-dawn hours of Shabbos.

The author expresses some halachic concerns regarding this innovative breakthrough. See the story and discussion in the original source by clicking here.

These concerns, as well as others, have formed the basis of the accepted halachic position that automated Shabbos devices and applications require precise rabbinic insight and endorsement, as to how and when they may be used.

The Zman Switch has been developed with intimate rabbinic insight and guidance through every phase of its development, earning the enthusiastic endorsement from our generation’s pre-eminent rabbinic authorities.

Using Refrigerators on Shabbos


Years ago when refrigerators became a standard home appliance, the question of using refrigerators on Shabbos was posed to many prominent poskim.

The problem originates with the general use of electricity on Shabbos. Is it permitted? Is it d’oraysa or d’rabanan? Some viewed electricity as an issur d’oraysa– a biblical prohibition[1], but most determined that the issur was d’rabanan. (This has implications in certain situations- even if using electricity is d’rabanan, causing the defrost to activate would be a d’oraysa as will be shown).

Today, the issur of using electricity has been established throughout the Jewish world and using any form of electricity today is unequivocally considered Chilul Shabbos.  Read More >