Can someone point me in the direction of some Halachic sources to research the subject of potentiometers on Yom Tov?

In the case of an oven, I had the understanding that as long as the fire was on there was no problem to raise the oven temperature on YT. Specifically, I am discussing gas ovens with an electric igniter and a manual temperature control. I understand that the dial is actually a potentiometer and therefore any rotation of the dial is actually an electrical change in resistance.

  • I think technically it is a rheostat which is used to control current. There is a quote from rav aurbach saying that even on shabbos we are only concerned with affecting voltage, not current but I don't recall where. I think it was about shabbos elevators. I've heard a few times rabbis giving shiurim that adjusting a knob like that is theoretically fine, but nobody wanted to actually pasken like that limaaseh. +1
    – user6591
    Commented Sep 26, 2017 at 23:38

1 Answer 1


The situation is that the rheostat must be a continuous setting situation (analogous to a gas stove with the flame already on). If the dial causes the switch to click from one setting to another, then it is forbidden. Similarly, if an indicator light goes on and off as you turn the dial then it is forbidden. This is like a gas stove top with an electric spark that starts the flame (which is forbidden). This is as I explain at Can you use electricity on Yom Tov

Oven Kashrus For Yom Tov Use


As with cooktops, one is forbidden to directly initiate a fire or heat to an electric coil due to the prohibition of molid. If the oven was turned on before Yom Tov, the temperature setting may be raised as necessary for cooking if one is sure that electricity is flowing to the element at that time or there is no digital readout. Also, one may not cause a light or icon to go on during Yom Tov. If a light goes off and on indicating when power is flowing to the heating element, then the temperature may be raised when the light is on.

Generally speaking, one may lower the temperature only if it is necessary for the Yom Tov’s food and if a light or icon will not be turned off.

If an indicator light displays when power flows to the oven, one may lower the oven temperature when power is not flowing (indicator light is off) even if it is not needed for the food.

Some Sabbath Mode ovens are designed to work on a delay when in Sabbath Mode, the display will not change. In addition, this feature permits raising the temperature on Yom Tov at any time, regardless of when power is flowing to the oven. This is because when one adjusts the dial or keypad, it is not directly causing the temperature of the oven to change. Therefore, this action is considered a grama, an indirect action, which will cause the temperature to be raised. Even with these types of ovens, it is better to lower the temperature only when necessary for food preparation or enjoyment of the Yom Tov. (Other features of Sabbath mode ovens are discussed further in this article.)

  • So lowering the oven temperature should be fine, but fully turning it off would be a change of state and not allowed? Commented Sep 27, 2017 at 2:49
  • @user1389579 Yes. Similar to a gas stove. Note that it can be done only to prevent the food from being ruined. If there is no food on the element then it is kibui (extinguishing a fire) and forbidden. Commented Sep 27, 2017 at 3:39
  • Correct. I wasn't clear. I meant lowering it when the flame was already off. Commented Sep 27, 2017 at 17:52

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .