Keilim 7:2-3

Keilim 7:2

A hob (a protrusion from a stove) that has a receptacle for pots is insusceptible to ritual impurity as part of the stove but susceptible as a receptacle. Regarding its sides, whatever touches them does not become unclean because of the stove, Rabbi Meir rules that the wide side (where the hob connects to the stove) is insusceptible to ritual impurity but Rabbi Yehuda declares it susceptible. The same applies if one inverts a basket and makes a stove on top of it.

Keilim 7:3

A stove that was split in two lengthwise (through its two cooking areas) is insusceptible to ritual impurity but one that was split in half between its two cooking areas remains susceptible. If a mini-stove (which has only one cooking area) is split into two parts, whether lengthwise or widthwise, it is not susceptible to impurity. The extension around a stove (i.e., a pan at the base) is susceptible to impurity through contact and through its airspace when it is three fingerbreadths tall; less than this, it is susceptible to impurity through contact but not through its airspace. Rabbi Yishmael says that the airspace of an extension is measured by resting a spit from above to below. Whatever falls opposite the extension is susceptible to impurity through the airspace. Rabbi Eliezer ben Yaakov says that if the stove is rendered unclean, the extension is also unclean, but if the extension is rendered unclean, the stove is not.