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Dwight Romberger

Should I put the battery disconnect on the + or - battery post?

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Hi All,

I am just finishing a total OEM rewire on my 1936 International pickup. It is 6 volt POS ground. Does it make a difference which battery terminal I put the disconnect switch on?

I am having a brain freeze.

Thanks,

Dwight

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Don't know if there is an official way, but electrically it should not make any difference. As long as there is not a space or clearance issue that forces you to use one post, I'd lean toward putting it on the post where the cable to the starter goes if for no other reason than that suits my sense of esthetics.

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Thank you for the quick response.

The best I can remember is that it is the convention to remove the ground wire on a NEG ground battery because if you removed the POS and it dropped down against the engine or frame---fireworks.

Since I am not removing anything, I will use what fits best.

Thanks!

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The best I can remember is that it is the convention to remove the ground wire on a NEG ground battery because if you removed the POS and it dropped down against the engine or frame---fireworks.

That's not entirely correct, but the real reason why I always put the disconnect on the negative (ground) terminal is that if you disconnect the positive terminal, a wrench dropped on the positive terminal will still arc if shorted to ground. That will not happen if the negative side is disconnected. Of course, if a vehicle has positive ground, reverse that logic (and the location of the disconnect).

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The accepted practice is to install the cutoff switch on the positive cable -- for a number of reasons, not the least of which is so that fire and safety personnel will always know where to find it.

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My opinion was for the negative post, the cut-off's all seem to have a green knob. Another thing about the cut-off is the fact that it's a huge piece of additional metal on top of the battery, susceptible to any nearby working tool's.

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My opinion was for the negative post, the cut-off's all seem to have a green knob. Another thing about the cut-off is the fact that it's a huge piece of additional metal on top of the battery, susceptible to any nearby working tool's.

I like Joe and Norm's reasoning. Since my truck has a POS ground---I will put it on the POS. (i will paint the knob red!)

Thanks All

Dwight

Edited by Dwight Romberger (see edit history)

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Joe is correct. Always switch the "grounded" terminal. That is the only way to completely isolate the battery and eliminate any chance of an accidental short by something touching the "hot" terminal.

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Thank's Dwight, however, the positve side of the battery will always be positive!, no matter what the car dictates.

The purpose of the cut-off is to shut down the electrical system, to prevent possible drains on it and to twart possible theives (who couldn't find the battery on some of these old car's anyway)

Putting it on the positive side simply adds a connection in your positve electrical system...another place for corrosion.

I think 92GTA knows something...........

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Thank's Dwight, however, the positve side of the battery will always be positive!, no matter what the car dictates.

The purpose of the cut-off is to shut down the electrical system, to prevent possible drains on it and to twart possible theives (who couldn't find the battery on some of these old car's anyway)

Putting it on the positive side simply adds a connection in your positve electrical system...another place for corrosion.

I think 92GTA knows something...........

No, sorry. The disconnect should always be on the GROUND side of the battery for the reasons I noted above. Dwight says the truck is POSITIVE ground, so the disconnect should go on the grounded POS terminal in his case.

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I normally remove both. As long as you remove one there will not be any power in the car .

The reason to remove the ground cable (POS or NEG) is so when you are removing or reinstalling the cable if the wrench hits any part of the car it will not short the battery to the ground . This is also the way to install a battery

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I was taught to disconnect the ground. That would be the Positive cable on my Positive ground (pre-1956) Packards. A 1956 Packard would have a Negative ground and that's the cable to disconnect on them. If you apply a green-knob disconnect device to the 'Hot' cable and the device comes into contact with oh, say... the battery hold-down clamp... you have the potential for an under-hood barbeque.

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ceteris paribus, it makes sense to disconnect the ground, whether it be positive or negative.That which is opposite ground is going to be hot, regardless. Looking around a car, it

definately appears that there are no shortagees of potential grounds since the car is one big pile of grounds, mostly. One can "weld" about anywhere one chooses, but with integrated circuits and other computer elements it may not be wise. Anyone know when closed circuit hot wires (isolated) first became commonplace? I would bet the first guy to do that was laughed out of town.Sometimes It just took somebody to say "well, why not"?. One seldom hears of ill consequences from the wiring of circuits on autos in this manner, so maybe the sparkee syndrome is not often a problem. Most emergency duty fuel pumps, GASOLINE, no less, are actuated by the ground wire. ARE sparks more prone to jump from ground to hot or vice versa?!

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Hi All,

I am just finishing a total OEM rewire on my 1936 International pickup. It is 6 volt POS ground. Does it make a difference which battery terminal I put the disconnect switch on?

I am having a brain freeze.

Thanks,

Dwight

Keep it simple - disconnect the hot lead

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