WTF? when i weld car locks and lights turn on

Hello,

i have a mazda 626 98,

i'm trying to remove a broken bolt (alternator pivot, bottom bolt).. i'm trying to weld a nut so i can remove the rest of the bolt..

the problem is that when i try to weld the damn car alarm (aftermarket) will turn on (the battery is discconected both terminals).. also the locks go on and off....

is that normal?? wat is going on... i tried couple of times and it keeps doing the same thing...