The "blue wire" is what my car had been wired with. Who knows when or who did it. All you need to do is put the fuse between the battery and your wiring harness. I think most original cars are wired to have that come from the starter foot switch up to the wiring panel. Fuse that wire. On my car, it was rerouted from the starter foot switch over to attach directly to the battery - either way is fine and routing it to the battery compartment means you don't have to crawl under your car to check for a blown fuse. Over 100+ years and half as many mechanics later, there's no definitive way to tell how your car is wired without looking.
The whole point is to put a fuse somewhere between the battery and the Car's wiring. If there's ever a short, the fuse will blow, and your car won't almost catch fire like mine did.
For proof, just look at my fried wiring harness after I had a faulty cutout get stuck in the ON position.
https://modeltstarters.com/voltage-regulators-cutouts/
Thankfully I recognized the smoke as burning wires and disconnected the battery as quickly as I could and saved the car. I had to rewire the entire harness under the dash and I also installed a fuse, and the car is ok. It's the reason I had 1000 fuse assemblies manufactured and I include them in my kit.
Here's a very helpful diagram and info from Ron Patterson.
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All, and I mean ALL, modern vehicles now have fuses so they don't catch fire and burn to the ground. Why take a chance with your T?
And if the fuse blows, your generator will be fine. Unlike cutouts, there's an automatic protection circuit built into my voltage regulators that shorts the generator to ground when there's no battery connected (like when the fuse blows). Even with just a cutout, installing a fuse is a smart investment. Replacing a fried generator is a LOT cheaper than fixing or replacing a car that's caught on fire.
I'm planning on writing up another tech tip covering this topic in detail.
Jeff
