Battery cutoff switch at the starter?

The A came with the positive terminal on the battery cabled to the frame, hence a "positive ground system". Later on, Ford changed (matching most of the rest of the industry) and made the negative terminal the ground, hence "negative ground system".

Many convert their A's to negative ground, usually as part of a 6v->12v conversion. But in ANY case, the cut-out switch in the ground wire is the best way to have it, regardless of "positive ground" or "negative ground".

Obviously, not all agree, but I think the accounts mentioned above are quite illustrative.
 
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I had quite an interesting experience with the plastic switch Tom mentioned.Somebody dropped off a John Deere 420 crawler to be fixed a few years ago.It had one of those plastic switches in the hot lead,just happens to be positive ground like the A.After pulling it off the trailer with the loader the owner got on and started to churn it over to try and start it.The plastic got hot,the stud and cable dropped out of the switch when it melted,and the cable dropped on a steel fuel line.When it arced it's way through the line the fire was on.That 1/4 inch line just fed that tank of gas to the fire for about 5 minutes.We stood behind the loader in case the tank got hot enough to ignite,but it never did.It was in an open dirt parking lot,so we just waited for it to burn itself out.If that switch had been it the cold line it would still have melted,but it would have just dropped out and laid there.I have a nice old Lorraine loader with the original switch in the ground line.Same with an old D6 Caterpillar,and an HD11 Allis Chalmers dozer.I do have a small excavator with the switch in the hot line.I never even knew it was there for a few years.I looked out one night and saw the lights were on.That was interesting,as they went off with the key switch,along with the engine.I found the key was off,and when I looked it over I found the machine has an electric battery disconnect.It had failed in the closed position.What I thought was a fuel shutoff clunk when I turned on the key was really a battery switch.That machine is Kubota powered,and they do some weird things with equipment.
 
With a cutoff switch on the ground cable, wouldn't a short to ground at the horn get hot? I prefer to switch the hot wire rather than the ground.
 
Bruce said:
With a cutoff switch on the ground cable, wouldn't a short to ground at the horn get hot? I prefer to switch the hot wire rather than the ground.
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No, everything is dead with either battery cable cut, but the ground side is the safer one to disconnect.
 
Again, (for this confused guy) the "ground" side is the wire coming from the positive battery terminal to the frame???? (on a positive grounded A)
 
Thanks I hope I finally got it. Sorry for all the questions. But this old brain ain't what it use to be!
 
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