[jbrewer]

10 amps of 12v is 120 watts. a 120 watt soldering iron will get very very hot...like 500F hot. 10A should be more than plenty.

If your fuse is in the same part of the circuit as the schematic indicates, then the ONLY load on that branch of the circuit is the PTO.

Some questions for you.

Does the fuse blow when you're actuating the pto, or just driving the tractor?

For a fuse to blow at 45 min , one of two things is probably happening.

1) There's an intermittent short or heavy load that just happened to occur at 45 min.

2) You were pulling right at 10A for an extended time.

Fuses are strange beasts. They're crude and not well characterized. If you look at the specs of a fuse, you'll generally see a fuzzy graph that indicates load versus time. A fuse will go a surprisingly long time at rated load before it clears.

Some more data to work with would be good. Increasing the current rating of the fuse or putting a slow blow in is not a fix.

So what were you doing when the fuse blew?

If the PTO was not actuated and it blew the first scenario is the most likely.

John