Must one immerse electric appliances?
Electrical appliances which are used to cook food, and come in direct contact with food, are obligated in immersion in a Mikveh with a blessing. This includes toasters, sandwich makers, water urns and the like.
How to immerse and avoid damage: One is to immerse it fully and not use it for 24 hours in order so it dry. One may also choose to disassemble the item and immerse only the parts that come in contact with the food and require Tevila [such as the grates of a toaster, and knives of a blender].
Other alternatives: If immersing the vessel will damage it, then there lies only one other alternative, and that is to give it to a Jewish professional take it apart and reassemble it. It does not suffice for one to give it to a gentile as a present and borrow it back from him for permanent use.
 Igros Moshe Y.D. 1/57; 3/24; Chelkas Yaakov 1/126; 2/62-3; Minchas Yitzchak 2/72; Shevet Halevi 2/57-3; Beir Moshe 4/100; 7/57; Kinyan Torah 4/90; Sharaga Hameir 4/105; Mishneh Halachos 9/162; Teshuvos Vehanhagos 1/450; Rav SZ”A in Sefer Tevilas Keilim p. 185; Hakashrus 4 footnote 88; Kashrus Halacha Lemaaseh p. 275-277
Other opinions: Some say that since electrical appliances are plugged into the ground, they therefore do not require immersion. The Poskim ibid negate this opinion.
 Beir Moshe 4/100; Mishneh Halachos 9/162; Teshuvos Vehanhagos 1/450; Rav SZ”A in Sefer Tevilas Keilim p. 185; Hakashrus 4 footnote 88; Kashrus Halacha Lemaaseh p. 275-277
Other opinions: Some Poskim rule a toaster does not need to be immersed as it is not a table vessel [Klei Seuda] and is not a true cooking vessel being the bread is already edible prior to the toasting.. [Igros Moshe 3/24; Rivivos Efraim 4/405]
 Kinyan Torah 4/90; Beir Moshe ibid
 See Hakashrus Kehalacha chapter 35 in name of Rav Mordechai Eliyahu
 Beir Moshe 4/100; Tevilas Keilim 4/16 in name of Rav SZ”A
 See Admur 323/5; Taz Y.D. 120/18