Why does a circuit breaker trip?
It's legs are too long and the wires are strung too high!
Why does a fuse blow?
Your circuits need anger management.
Seriously, if you are tripping CB's and you KNOW the draw is not in OL territory, you may have loose terminals/lugs or a bad CB.
If you don't know what that means, have a qualified electrician check out the branch circuit in question with a clamp on ammeter, etc.
Also remember that most kitchen resistance heater appliances can pull close to 100% of a 15A circuit. This is why a properly wired kitchen has no less than two 20 amp circuits just for outlets!
Cheers!
Cheers!