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  #1  
Old May 22nd, 2013, 06:36 AM
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Bill Adams
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Positive earth

I was pondering the reasoning behind making vehicles positive earth, and I am stumped as to why. If anyone has any insight into this I'd be happy to learn.
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  #2  
Old May 22nd, 2013, 07:07 AM
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Just out of curiosity/ignorance, I could ask the same question about negative earth. Other than common convention why is one better than the other?
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  #3  
Old May 22nd, 2013, 07:14 AM
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I've been asking the same question for years.

Is the same shit as why phones work at -48 Volts.

I assume they were drunk, hooked the polarity wrong and didn't say shit so they didn't look stupid.
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  #4  
Old May 22nd, 2013, 08:24 AM
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Well......Electron flow theory says that electricity flows from negative to positive. Maybe the first bunch of engineers preferred to wire it up that way? Electrons, not protons move during current flow. Electrons are attracted to protons, and repelled by one another, so they travel from the area of highest concentration (negative terminal) to the area of lowest concentration (positive battery terminal). If you follow that theory then you would think Positive Earth is the way to go right?

But....maybe it was just that batteries were so unreliable back in those days? I remember my grandad's old Massey Fergusson tractor could be started by bypassing the battery and putting two wires together on the starter motor, I forget how we used to do it - i just watched him.
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  #5  
Old May 22nd, 2013, 08:46 AM
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Quote:
Originally Posted by 1971Series88 View Post
Well......Electron flow theory says that electricity flows from negative to positive. Maybe the first bunch of engineers preferred to wire it up that way? Electrons, not protons move during current flow. Electrons are attracted to protons, and repelled by one another, so they travel from the area of highest concentration (negative terminal) to the area of lowest concentration (positive battery terminal). If you follow that theory then you would think Positive Earth is the way to go right?

But....maybe it was just that batteries were so unreliable back in those days? I remember my grandad's old Massey Fergusson tractor could be started by bypassing the battery and putting two wires together on the starter motor, I forget how we used to do it - i just watched him.
That's a good point.

Perhaps early folks thought of it electron flow and modern ones as current flow.

I'm not an early folk and been dealing with the "conventional" way (current flow).

Current flow won.
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  #6  
Old May 22nd, 2013, 09:33 AM
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Y'all are missing an important piece of British engineering theory which is that the British and their engineering are infallible. Remember that the concept of Positive Earth, just like RHD, originated at a time when it wasn't called the United Kingdom but rather The British Empire. As a result, that TBE decided was accurate and correct for the rest of the world to follow b/c it was decided by the most brilliant minds in the world.

Of course the Colonies played a rather significant part in taking the winds out of TBE's sails - they had the audacity to dump English tea into a harbour, drive on the left-side of the vehicle and use Negative Earth - all to spite TBE.

As for an engineering standpoint - engineers are like the historical TBE. If the thinking is solid and the processes, like the family trees in certain rural parts of America, are ram-rod straight, then the engineering is perfect. Hence the idea of Positive Earth - the engineers did their research and used TBE's approach resulting in a concept that was (and still is) considered to be bass-ackwards from the rest of the world BUT it worked and it showed a completely British form of thinking that was superior to all other forms.

Oh, yeah -
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  #7  
Old May 22nd, 2013, 09:41 AM
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------ Follow up post added May 22nd, 2013 09:46 AM ------

About a year ago I was chatting with a local stamp collecting guru about a stamp collection I was trying to place a value on. I had a bunch of stamps that I couldn't tell where they were from and he pointed out that the English didn't feel the need to put "England" or "Royal Mail" on their stamps because "they invented mail in the first place" and every other country came after. Typical.
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  #8  
Old May 22nd, 2013, 02:26 PM
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I think that Positive Earth on Land Rovers has slowed down the electrolysis between 2 dissimilar metals.
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  #9  
Old May 22nd, 2013, 02:54 PM
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Quote:
Originally Posted by badgerman View Post
I think that Positive Earth on Land Rovers has slowed down the electrolysis between 2 dissimilar metals.
But it wasnt just on Rovers. Just about everything British was positive earth. I had and early MGB that was. In fact, up to 67 they were.
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  #10  
Old May 22nd, 2013, 04:08 PM
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I always wondered about the positive ground thing too but I really don't get where left hand drive came from. Before cars, the person driving a carriage always sat on the right side - right hand drive. So how come it changed here later?
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  #11  
Old May 22nd, 2013, 04:56 PM
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This is an extremely nerdy response, so I apologize in advance, but current is carried via electron motion in the conduction band of the metal. There are no positive charge carriers (only the motion of electrons matter), but the definition is correct - the electrons will move in the opposite direction of current.
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Old May 22nd, 2013, 04:57 PM
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Quote:
Originally Posted by LRover View Post
I always wondered about the positive ground thing too but I really don't get where left hand drive came from. Before cars, the person driving a carriage always sat on the right side - right hand drive. So how come it changed here later?

http://en.wikipedia.org/wiki/Right-_...t-hand_traffic
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  #13  
Old June 16th, 2013, 05:40 PM
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What I heard was that positive ground is better for cars but negative ground is better for radios and or radio waves/interference.
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  #14  
Old June 16th, 2013, 05:52 PM
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+ Earth

Years ago it was thought that because electrons in atoms were changed negatively that current flowed easier and more smoothly from + to - . This was proven not to be the case years later when the first alternating current alternators were invented for automotive use. At that time the British automotive industry switched from + to - ground. The rest is inverted history so to type!
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  #15  
Old June 17th, 2013, 10:08 AM
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Negative to positive... typo

Last post should have read:
Years ago it was thought that because electrons in atoms were changed negatively that current flowed easier and more smoothly from - to + ground with less "noise". This was proven not to be the case years later when the first alternating current alternators were invented for automotive use. At that time the British automotive industry switched from + to - ground. The rest is inverted history so to type!
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  #16  
Old July 16th, 2013, 12:35 AM
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Yes, it was whispered a few posts up. The reluctance to change with the rest of the world to negative earth was in part to reduce galvanic corrosion. Mixing ally panels over steel frames, add water, a little salt, flow a bit of electricity through it---

Positive earth reduced the damage. You might also notice most of the Land Rover has a network of earth wires instead of just grounding to the body or any other metal component.
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