We were having a discussion today at work about positive ground vs. negative ground electrical systems in cars. Everybody there had a good understanding of auto electrics, but nobody could say definitively why negative ground was better. I wonder if some of you here could shed some light on this subject for us. For the most part, American car manufacturers used positive ground electrical systems in the 6 volt days (except for GM, REO, Ford Model T's, some Lincolns and pre-GM Cadillacs) until they switched to 12v around 1955, then they all (except for Packard) switched to Negative ground electrical systems. The question is why. What is the advantage of negative ground electrical systems over positive ground systems? I know that some of you on this site have a background in electrical engineering, and many of you have forgotten more than I'll ever know about electricity, So I ask you to please tell us - What are the advantages to having a negative ground electrical system in a car versus positive ground?
Chevy used negative ground 6 volt in their trucks while GMC used positive ground in their trucks.Same Delco electricial system.There's theories on current flow ,corrosion and what not,but in the end it makes no difference.Negative ground just seems more natural...........
Electrically, it makes no difference whatsoever. Negative ground was emotionally preferable since it gave the mental image of the 'positive' being good and above it all, with the 'negative' the lowest, or ground. Just hype. Many early cars had positive ground but the convention of negative ground prevailed. Again, electrically it is irrelevant.
Standardization. Household code needed it so it carried over to everything. Can you imagine the world with out standardized electrical code? It would smell like pork and we would all have frizzled hair.
As others have said, the current flow makes no differance at all, it must have been an attempt to have a standard. In the early days of electronics the engineers thought current flowed from positive to negative, but at some point they relized that the current flow is the movement of electrons that are negative charged. and just like a magnet the negative charged electrons are attracted to positive. They figured all this out back in the '20s or so (i think) way before the cars made the switch to the now standard negative ground system. But you know, some lines of engineering progerss faster than others, or is it just that some resist change.
Black and Red have been used for the color code for positive and negative for quite some time. Just the same, black was commonly used as the color for a ground wire, along with white. I would assume the basic car owner at the time would have had a hard time remembering this little piece of information, thus negative ground was implemented and your "Hot" wire was red. For most people the color red is associated with hot, easy to remember. This is all speculation on my part, but it would of made sense at the time anyway.
standardization x2! ever purchased a vehicle after somebody attempted to fix electrical issue with the cord off mom's old lamp!
Dodge Brothers started in 1915 with 12 volt negative ground. In '22 they moved the horn button from the door to the steering wheel and found corrosion was a problem, so they switched to positive ground. Kept P.G. even when they went to 6 volts. I think MAck trucks kept positive ground for a long time too.
Maybe they didn't understand the question?? Absolutely no advantage of either. Conversion from one to the other is flim-flam. Early on, 20s to 30s, different manufacturers did it different to confuse the consumer. Then when it became obvious that standardization of accessories, etc. was to their advantage(the manufacturers), negative ground became the standard.
Positive ground basically "electrified" the whole vehicle, meaning that the current was carried through the chassis. Current (or Amps) flow from the positive terminal of the battery to whatever the load is, then they are converted into whatever the device does-meaning that the amps that go to a light are converted to light and heat. The return path of the circuit now carries no (or nominal) amps. To further muddy the water, the "positive" terminal on your battery is actually the negative terminal. They "mislabel" the battery to avoid further confusion Okay, not really: the gub'ment changed it all over after an alien craft was studied...
really? The amps just "disappear" in the device? So if i disconnect the negative side (earth lead) of my batery and plug an ammeter in line with the negative battery terminal and the earth lead, then turn something on in the car (stereo, headlights etc) the ammeter will show a zero current reading??
I read somewhere a long time ago (fuzzy memory) that the positive ground ignition systems would run out of steam above a certain speed. Looking back at the records set before WWII, I tend to think this was a lie foisted on the general public in an attempt to get them all to swallow what was good for them (standardization). There are other cases of pushing a lie to get the general population to do something for the general good....
Thanks for all the responses. I thought maybe it had something to do with reducing corrosion. Sort of like in electroplating, where the positively charged anode dissolves into the solution and collects on the negatively charged cathode. If the body has a positive charge (positive ground), it becomes an anode, maybe it would be likely to corrode faster than if it was negatively charged. I'm probably just over thinking it though.... What a coincidence, when this question came up, I was working on a '53 Meadowbrook Suburban, and it is definitely staying 6V.
Someone changed my '51 Packard to negative ground. I googled the part number of the Delco regulator that they used and it is supposed to go on a '54 Chevy. All of the other electrical stuff is regular Packard Delco. Interesting. The radio works but has a buzz. I read on a Packard site that that was what would happen if you hooked it up wrong. I will probably change it back to positive ground. pigpen
Standaraztion is all--postive ground systems do not corrode like our standard negative ground--after 25 years in a starter and alternator shop I have seen it all--I used to enjoy watching people work on positive ground. NoBoDe--the Mac trucks--some of them started on 24 volts--charged at 12 volts --all positive--really thru people for a loop--
8 track vs. cassette Beta-max vs. VHS Blueray vs. High def, There has to be a winner and there has to be a looser when economic reality forces a decision.... Pos ground lost
Yes. ... and they don't "disappear", they are "converted". Amps are a measure of electrons flowing through a circuit. Voltage is a measure of electrical pressure. Voltage remains constant no matter where you look on a simple circuit but amps do not.
I always read electrical posts, because nobody ever agrees on an answer, if in fact there is one. Too old to ever understand electricty, if a bulb burns out I just replace it.
Wow, there's a lot of misinformation on this post. I don't know what the advantage is to a negative ground, nobody should answer if they don't know! I do know that electricity does not flow from the positive terminal, it flows from the negative. If you switch the poles, the electrical system will still work just fine, there are no corrosion issues with either type greater than the other, neither system "electrifies" the whole car any less than the other (if the electrical system grounds to the vehicle, it carries current no matter what type of ground), and no amps, volts or watts ever disappear. Electricity isn't magic, people.
I've read, several times through the years, that it went to NEG GROUND because it changed the DIRECTION (from POS GROUND) that the spark JUMPS between the center electrode and the ground on a spark plug, causing the center electrodes to deteriorate LESS using a NEG GROUND system. DD
Not me. I'm currently (pun intended) in the middle of changing our '47 Mercury over to 12 volt, negative ground. No more dim lights and lazy starter! I once had a '65 Triumph Herald sedan. It was positive ground. (Oh, I mean positive "earth", those British!) It never occurred to me that the British wired their cars "backwards" like that until I tried to hook up a cheap, parts-store radio. It fizzled and popped and all the smoke got out. I didn't know what happened until I went back up to the store for another radio and the guy told me to check to make sure the little polarity switch on the back matched the car's system.
Basic Electronics: In any DC electrical system,the current (amperage) flow is From Negative To Positive. You can prove this with a diode.
Battery terminals and electricity in general was named wrong in the beginning. When vaccum tubes came along ie radio in the mid teens (deforest) it became painfully obvious that current flowed from what was called the negative post to positive. By then traditon had already estabished it in cars the otherway around. When the switch came to twelve volts they corrected the mistake. Does it make any difference if the car is wired uo properly for it? Probably not. What they should have done was just renamed the battery terminals and all electrical terminals but they didnt so we are stuck with this cunundrum. If you want to prove it out. Put some Arm and Hammer washing soda in a plastic bucket . Take dirty metal part and clamp the neg to it. Clamp a steel rod to positive and place it in the bucket making sure the two metal parts do not toch. Within minutes the bubbles will rise from the dirty part along with the dirt andyou will see it swirling in a circle slowly depositing itself on the pos rod. Within an hour if you remove the metal rod it will be covered with the crude that was once on the dirty part. You need a battery and a battery charger to make this work well but it is interesting and very graphic. Don When i taught trade school part of the cirriculum for electrical (which was one subject i always taught) was to teach them Electrical Theory (pos to neg) then Electron Theory (neg to positive) I would but would tell them immediately it (+ to -) was wrong and not so. It seemed stupid to teach it but it would be on their trade exam so you had to. Sort of like teaching the theory of evolution that we came from monkeys as a solution to everything all the time ignoring the 64,000 dollar question "where did the monkeys come from. " Clearly some of us may be descended from pigs rather than monkeys judging from our habits and language Don VE3LYX (Ham radio callsign)
Is the earth (the dirt, the ground) negative? What I'm asking is ---if you pound a metal spike into the ground and treat it like a negative terminal-- say by putting a light bulb between it and a battery's + terminal, will the bulb light? [I'm gonna try this today] I know this works with alternating current, but I thought direct current has to return to its source to complete the circle of the "circuit" in order to flow (as opposed to "bounce back" in AC). I have a 6V pos gnd car. Suppose I installed a second 12V battery (for a 12 V stereo) in the trunk and wired it neg gnd. What happens at the radio when the case of the radio touches the body of the car? Will time travel occur?
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