Why is it suggested to put a disconnect on the negative side of battery versus positive interruption?
I was told a long time ago to cut the ground link to kill the electricity flow. This is a full proof way to make sure all of the electric circuit is cut. So if the T is negative ground kill the negative side, if positive ground kill the positive side.
Might be just an old wise tell, but I have found that the old man is usually correct on things. He has gotten really smart since his passing.
If your wiring is up to snuff and no modifications have been done a disconnect is not needed...
I put a disconnect in my car to be on the safe side. I usually leave the car in gear when I park it, even in a store parking lot. I often let admirers of the car sit in the car and I will take their picture with their phone. I also let parents put their kids in the car to take their picture. I don't want to risk someone unfamiliar with the car stepping on the starter, and having it jump because I left it in gear.
I put them in all of mine for the exact same reasons.
I've heard it said by some people whose opinion I respect that a battery cut-off switch is not needed in the case of a car that has been wired up correctly. -Okay, fine. -I look at my Flivver, which was partly wired up by the previous owner and partly wired up by myself and ask, "Was my car wired up correctly?" -I dunno. Maybe.
I've heard that a lot of vintage collector-cars do suffer electrical fires and my guess would be that many of their owners thought the electrical systems were okay. -They were wrong.
In my case, the battery cut-off switch serves two purposes.
1.) -It kills the floor-mounted starter button so I can safely pose spectators in the car for pictures and know that the nothing frightening will happen if some kid steps on the button.
2.) -My garage is attached to my house and I sleep nine feet above my Model T and its 10-gallon gas tank. -Even if I were sure that my electrical system was correctly wired up (and how such a guarantee could be made in the case of one of these ancient, multi-owner cars is beyond me), the extra layer of protection provided by the cut-off switch is additional insurance. -And to those who insist that the switch is an unnecessary pacifier, my reply is: Hey, it couldn't hurt.
Now, many of the overseas-made battery cut-off switches in the catalogs we usually peruse are not of the greatest quality in the world. -My switch is one of those and replacing it every five years (along with the overseas-made, reproduction starter button) has been part of the regular maintenance routine. -But next time, instead of buying it out of an auto parts catalog, I'll visit my local, neighborhood marine store (the kind that sells boating equipment, not military boots and brass belt-buckles) and buy the best made-in-USA battery-disconnect switch they have.
I used a "Caterpillar" brand (USA then) master disconnect from my Heavy Equipment Operator days - been on my Racer for almost 30 years, I guess.