Question: [Wednesday, 2nd Kisleiv, 5781]
How does one Kasher an electric stovetop?
There are different types of electric stovetop which carry different laws.
Kashering elevated coils [i.e. coil cooktops]: The old-fashioned electric stove tops that are made with the electric coils raised above the surface area of the stove, are Kasherable by simply turning on the stove and have the coils turn bright red. This is synonymous with Libun Chamur, and helps to Kosher from dairy to meat or vice versa, or from non-kosher to kosher, or from Chametz to Pesach. The surface area of the stove however may nonetheless remain non-kosher depending on its material. However, this does not pose a problem for the pots being that the pots do not rest on the surface at all.
Kashering the modern flat electric stove tops [i.e. smoothtop]: Flat electric stove tops in which the heating element is under the surface, under the circled area on the surface of the stove, have a serious question regarding their Kashering status. First of all, they are usually glazed with glass which is considered non-Kasherable for Ashkenazim, at least in regards to Pesach. [For Sephardim, this is actually an advantage, as it allows a simple cleaning of the surface to be a valid form of Kashering.] Another issue at hand, is the fact that even if one were to determine that turning on the electric stove suffices for Kashering the circles on which they are under and that the pot rests on, often the pot extends past this area and onto the surface area that contains no heating elements under it and is therefore not Kashered. Practically, Ashkenazim should avoid Koshering it for Pesach use and rather use a replacement stovetop. Nonetheless, one who desires to Kasher it [for Pesach, or year-round use], is to clean the surface very well and turn on the stove to the highest temperature for an hour. The surrounding area which does not get hot, but sometimes has a pot resting on it, should have boiling water poured over it and be covered with tinfoil [at least when Kashering for Pesach]. Alternatively, if one does not want to cover it with tinfoil [such as if he desires to Kosher it for year-round use] he is to [in addition to pouring boiling water over it] make sure that it is always clean of any residue and that the pots placed on it are not wet on their bottom, and should also try to make sure that they don’t overflow during the cooking. Bedieved, so long as the surface area was clean, everything remains valid [even on Pesach].
Induction cooktops: Induction cooktops are the most Halachically complex in terms of their Kashering. Practically, being that they share a glazed glass surface similar to a regular electric smooth top stovetop, therefore their leniency would be similar to that of the electric stovetop, although regarding Pesach Ashkenazim should avoid Koshering it. Practically, one who desires to Kosher it should place the special magnetic pot on it that covers the entire induction area, and thus have it be Koshered by the pot causing it to heat up, and having it remain there for about an hour. The surrounding area should then have boiling water poured over it and be covered with tinfoil, or done as stated above regarding a flat electric stovetop.
Sources: See Chelkas Yaakov 1:98; Emunas Itecha Tamuz 5773 p. 158; Piskeiy Teshuvos 451 footnote 99; Nitei Gavriel Pesach 7 and other Melaktim of today; See our online articles on the status of glass as well as on the use of a stove for meat and milk and that various leniencies apply even for Ashkenazim