Throughout the year, people usually use the same stovetop grates for both meat and milk, because even if some meat or dairy liquid spills onto them, the flame incinerates and befouls it (Peninei Halakha: Kashrut 25:9).
Technically, for Pesaḥ as well, regular cleaning suffices. However, due to the seriousness of the ḥametz prohibition, people customarily perform light libun on such grates to kasher them for Pesaḥ (Rema 451:4; MB ad loc. 34). Alternatively, one may wrap thick aluminum foil around the bars on which the pots sit, creating a barrier between the Pesaḥ pots and the grates that came into contact with ḥametz. In addition, it is customary to turn on all the flames and let them burn for about 15 minutes.
For the areas of the grates that do not come into contact with the pots, the enamel cook top beneath the grates, and the burner caps, it is sufficient to clean them well.[2]
Electric ranges: Clean thoroughly and run on the highest setting for about 15 minutes.
Ceramic burners: The surface on which the pots are placed is like smooth, impervious glass. This surface is heated up electrically, and it, in turn, heats up the pots on it. Based on the principle of ke-bole’o kakh polto, they are kashered by cleaning and then heating them up on the highest setting for about 15 minutes.
Induction cooktops: The surface on which the pots are placed is like smooth, impervious glass. However, unlike ceramic burners, in which the heat source is within the ceramic surface, in induction cooktops the heat source is in the pot, which heats up by means of a magnetic field. From the pot, the heat spreads to the food cooking within it and to the surface on which it is standing. Ḥametz is liable to be absorbed into the cooktop via food that overflowed from the pot, some of which can get stuck to the base of the pot and continue to heat up along with it. Such cooktops are therefore kashered by cleaning them and pouring boiling water over them. Kashering them from the food that overflowed and got stuck to the bottom of the pot is based on the principle of ke-bole’o kakh polto: wet the bottom of the pot when they are empty, and heat them up on the cooktop for about 15 minutes. (Below, in section 14, the obligation to kasher glassware is discussed.)
