[Tommy]

It sounds like a hot wire is grounding out intermittantly to me too. Those can be hard to find, but if the car has a fiberglass body, there won't be too many places where the wires are close enough to a ground to touch. The only other thing I can suggest is to turn on the lights while parked in the garage, and then try jiggling the wires to see if you can reproduce the blown fuse. That may help you locate the shorted circuit.