Could this possibly be a new unit with an electronic oil primary? If it is look then to see if it is a 7148-1032 control. If it is then look to see if you see the sideways number 6 at the end of this number. If the answer is yes, then replace the Oil Primary control.
If you amperage is close to or exceeding the rating of the breaker when the boiler starts up, you have a short somewhere. if you don't own a tool that measures amperage, switch out that breaker with another one of the same amperage rating in the panel. my guess is it will be 15 amps. If the boiler stays on and the breaker you moved somewhere else still trips, you have a defective breaker (one that trips when notheing is wrong with the load). breakers rarely fail but it is a possibility. a clamp on amp meter is an excellent tool for helping diagnose this type of problem. I think lowe's and home depot carry them.
I don't know if anyone else has had this problem. I am not sure if my boiler is short cycling, but I keep having to go to the fuse box a couple times a day, and turn the switch off and then on to get the boiler to fire up again. It seems like something is every so often, and I have to keep resetting it. Does anyone have any suggestions?