Hard to say. You can find out. What you need to do is to set up a situation where you protect the car against more damage as you troubleshoot.
Get yourself a test lamp or "better" is a larger lamp like a dome, stop, or even a headlight. Rig it with clip leads/ battery clips. Unhook the battery ground lead. Wire the test lamp in series from the battery post to ground. Repair the fuse link, even temporarily.
Turn everything off in the car, don't forget things like glove box, dome, trunk lights, etc, and if your test lamp lights, the short is still active
If no light, "think" what you did to cause the short.
Key in run? Key in start? This is where things get more complicated.
If the test light comes on with nothing 'on' in the car, look around and make SURE everything is off. Don't forget dome lights. Pull out the cig. lighter and leave it in the ashtray. Remove fuses one at a time. Go out front and unhook the alternator output wire and tape it off safe.
Now, back to the ignition switch. If the short happened when you twisted the key, this gets more difficult
Look carefully under the hood for melted harness, ignition components. You have an electric choke? Examine it for damaged wires, etc, or any bare wires. This kind of thing, ya hafta get out yer "noggin."
DO YOU have any added acessories which might have shorted? tach? stereo?
From here, it gets worse. Go to the parts store and get a 20 amp breaker like one of these:
https://www.ozautoelectrics.com/med...5e06319eda06f020e43594a9c230972d/8/7/8782.jpg
Temporarily wire this in place of the fuse link. Try to duplicate the problem, IE key in "run" or start, etc. If the short is active, the breaker will cycle, on/ off.
Now disconnect "stuff" one at a time and see if the short goes away.
First thing to try is the field connectors on the alternator.
Next, pull the regulator connector loose
Next, pull the electronic ignition connector loose, or, if you have points, pull the connectors off at the ballast resistor.
If it happens in "start" there are only two circuits that can be
One is the start wire to the starter relay
The other is the brown bypass wire to the ballast which goes electrically to coil +
