▁tri ps ▁a ▁lever ▁switch ▁to ▁activ ate ▁the ▁he ating ▁elements , ▁and ▁their ▁thermal ▁expansion ▁is ▁har ness ed ▁to ▁lower ▁the ▁bread . ▁ ▁When ▁the ▁to ast ▁is ▁done , ▁as ▁determined ▁by ▁a ▁small ▁b imet all ic ▁sensor ▁actu ated ▁by ▁the ▁heat ▁passing ▁through ▁the ▁to ast , ▁the ▁he aters ▁are ▁shut ▁off ▁and ▁the ▁pull - down ▁mechanism ▁returns ▁to ▁its ▁room - temper ature ▁position , ▁slowly ▁raising ▁the ▁finished ▁to ast . ▁This ▁sens ing ▁of ▁the ▁heat ▁passing ▁through ▁the ▁to ast ▁means ▁that ▁regardless ▁of ▁the ▁type ▁of ▁bread ▁( white ▁or ▁whole ▁gra in ) ▁or ▁its ▁initial ▁temperature ▁( even ▁fro zen ), ▁the ▁bread ▁is ▁always ▁to asted ▁to ▁the ▁same ▁consist ency . ▁ ▁Ris ks ▁To aster s ▁cause ▁nearly ▁ 8 0 0 ▁death s ▁ann ually ▁due ▁to ▁elect roc ution ▁and ▁fires . ▁P oking ▁kn ives ▁and ▁other ▁objects ▁into ▁a ▁to aster ▁is ▁dangerous ; ▁aside ▁from ▁a ▁risk ▁of ▁elect roc ution , ▁such ▁insert ion ▁can ▁damage ▁the ▁to aster ▁in ▁ways ▁that ▁can ▁increase ▁the ▁risk ▁that ▁the ▁to aster ▁will ▁later ▁start ▁a ▁fire . ▁Even ▁without ▁such ▁tam per ing , ▁to aster s ▁can ▁cause ▁house ▁fires . ▁ ▁Research ▁ ▁A ▁number ▁of ▁projects ▁have ▁added ▁advanced ▁technology ▁to ▁to aster s . ▁In ▁ 1 9 9 0 , ▁Simon ▁H ack ett ▁and ▁John ▁Rom key ▁created ▁" The ▁Internet ▁To