Turning on high beams....blowing fuses??

Hello, We have a 1930 five window coupe that my husband rat rodded out about 4 years ago. We seem to be having a problem lately with the fuses for the high beams. Driving along at night and if he turns on the high beams, the fuse blows.
He replaced the fuse this morning and has been trying to get it to blow. He's thinking that it only happens once the car get hot from driving a while. So are we correct in thinking that it's a wiring problem or something in the fuse box itself?
Thanks for your help...I'm new here but hoping someone can give us an answer. We are headed to Back to the 50's in less then 2 weeks and need to get this fixed asap.
Julie

Doubt it's the fuse block since that is very rare. More likely the wiring. Could be a loose connection, bad ground, or the wire insulation has chafed somewhere along it's path and is shorting intermittently. Once all that's checked it could be a bad bulb, unplug one and see if it makes a difference, then the other.

I'd say it's in the switch. Foot switches are known for this more so than wheel switches because of the ground.
Good Luck & let us know when you fix it what it was........