sr20det ignition fuse problem

[nissan~240sx]

this has happened to me 3 times now where i have been driving along under normal conditions and the ignition fuse blows turning my car completely off while i am driving. now i just recently had my alarm taken out which cut the ignition if it wasnt unalarmed. i think they may have messed up a ground or something because one time i went over a bump on the highway and the car just shut off on me. it starts back up when i throw another 30A fuse in there but i was jsut curious as to why it keeps blowing the fuses. i have a lot of traveling ahead of me this weekend on the highway and need a solution fast...