If a person needs to cook on Yom Tob, is he allowed to turn on a gas stove?
Although Halacha permits cooking on Yom Tob, it is forbidden to kindle a new flame on Yom Tob. One may light a flame from a preexisting fire, but kindling a new fire, such as by striking a match, is forbidden. Thus, one may not turn the knob on his gas stovetop to create a flame on Yom Tob. It is permissible, however, to ask a gentile to turn on the stove so one can cook on Yom Tob.
If one needs to cook on Yom Tob and there is no gentile present to light the stove, is there a permissible way to turn on the stove?
Hacham Bension Abba Shaul (Israel, 1923-1998) addresses this question in his work Or Lesion (vol. 3, 20:5; listen to audio recording for precise citation), and he writes that one may light the stove if he has a candle that was lit before Yom Tob. If a person has a candle, he may take it and bring the flame right next to the burner on the stove. He may then turn the knob to kindle the burner. Even if the stove will create a new flame, and the fire will not be lit from the candle, it is nevertheless permissible to light the stove in this fashion. Since the person arranged it in such a way that the burner could light from a preexisting flame, he does not violate Yom Tob if a new fire is kindled on the burner.
It should be noted that Halacha forbids extinguishing a flame on Yom Tob. Therefore, one may not turn the stove off once it has been kindled on Yom Tob, and, similarly, one may not extinguish the candle on Yom Tob.
Summary: One may not turn on a gas stove on Yom Tob, but it is permissible to ask a gentile to turn on a gas stove on Yom Tob. Furthermore, one may turn on a gas stove on Yom Tob if he brings a preexisting flame near the burner when he turns on the gas. It is forbidden to extinguish a flame on Yom Tob.
