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23rd February 2021, 01:20 PM
#1
Negative Earth V Positive Earth
This will probably open a can of worms.
We had a very experienced (older) maintenance bloke come over to the Island to fix our generator and he commented on how much rust was evident on the outside. It sits out in the weather and considering lack of proper maintenance it receives, the 23,000 + hours running time is amazing.
He also commented that the old American cars that were positively earthed did not rust as much as negatively earthed vehicles from the rest of the world. How is this so? There must be a scientific answer for steel and electricity to make rust. I wish I studied chemistry at high school instead of just attending class.
If this is true, I can understand why they changed to negative earth because if a car did not rust away, they would not sell more new cars
At the end of the day, all you have is yourself and all you need is your friends (and in our case our Patrol)
2006 GUI1 4.2TDi Coil Cab "almost" standard
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23rd February 2021 01:20 PM
# ADS
Circuit advertisement
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23rd February 2021, 04:16 PM
#2
Expert
Interesting considering cathodes and anodes used on ships hulls for corrosion prevention, normally the anode (positive charge) would erode instead of the cathode (hull), so if anything positive earth or in vehicles case positive ground points would likely encourage corrosion in the copper wire, same principle as cathodic protection..anyhow, too many beers and dead brain cells ago to debate so have a read here
https://mgaguru.com/mgtech/electric/et098.htm
and draw your own conclusions.
2005 Y61 GU rebuilt 2020. 6.5 L turbo inter-cooled Diesel, SupENG Superflex 4 Inch Lift Kit 2,0 Remote res Fox shocks, offset trunions, 315/75/16 Maxxis Razr, 16 x 8 steel rims, SupENG drop box, Stedi Spots & bars, 12000 lbs winch,rear locking bars with duel tire carriers, 4” XtremeENG S/S snorkel, rock sliders, SME UHF, ARB Hard mount Air compressor, ARB fwd & rear air lockers,Rhino roof racks, Duel battery set up, 12 V dist swbd ,
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23rd February 2021, 11:11 PM
#3
.........
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mudnut (23rd February 2021)
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24th February 2021, 10:11 AM
#4
Expert
Telephone exchanges used 50v with positive earth to avoid problems with electrolysis. The positive earth system means that the ground side of things is the side that gets depleted (the anode) which matters when dealing with things like the very fine wire of the relays and electromagnets etc which were the basis of the old telephone 'step-by-step' technology. This started with the poms who probably had a much bigger problem with moisture (based on their climate) which is a key ingredient for electrolysis - if it is kept dry then there is little issue either way.
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24th February 2021, 06:09 PM
#5
Expert
Are land rovers still positively earthed?
2008 CRD Auto Wagon
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25th February 2021, 09:53 PM
#6
No expert at all but the major oil pipelines I've been on all have 'cathodic' protection sites situated regularly along the main lines. I was told this was to help prevent corrosion of the pipeline.
Not my field of expertise though. Where's @Cuppa?
Between Patrols ATM. Had a beaut GU with 6.5 Chev TD. Next is a GU ute with a 4.5 litre Cummins conversion and a camper on the back.
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26th February 2021, 09:05 AM
#7
Travelling Podologist
Originally Posted by
FNQGU
No expert at all but the major oil pipelines I've been on all have 'cathodic' protection sites situated regularly along the main lines. I was told this was to help prevent corrosion of the pipeline.
Not my field of expertise though. Where's @
Cuppa?
A little birdie tells me you know exactly where I am! Hope you had an enjoyable time out west. I actually went looking on the ‘net for the answer to this question about why cars changed to negative earth. In a nutshell I could find no agreement, only several different reasons repeated many times.
The cathodic protection thing which I reckon is a bit suss, something to do with a change to alternators with internal diode control which sounded possible even though I didn’t fully understand it, ��, and also suggestions that it was somehow cheaper for the manufacturers... which I also didn’t quite get. Another possibility was the introduction of radios into cars - perhaps anyone who knows a thing or two about radios might comment?
Last edited by Cuppa; 26th February 2021 at 10:01 AM.
2006 4.2TDi ex-Telstra Remote area Camper. 425w roof mounted solar, 360Ah Aux batts, BCDC1240, Onboard hot & cold pressurised & filtered water, (25 litre hot water calorifier), ARB fridge, ARB freezer, Built in kitchen, heaps of easy access storage, 240v, 3” Genie exhaust + dynotune, 2” lift, 3900kg GVM upgrade, second glovebox, ROH Blaktrak steel wheels, Bridgestone D697's (now Toyo RT's), Redarc gauges/pillarpod, Hema HX-1, Icom 450 CB, dual rear view cameras, Onboard 30amp Victron mains charger, second glovebox, dual seat conversion, TPMS, Boss PX7 onboard air with 9 litre tank, 350w inverter, Steel bullbar, Harrop Eaton diff lock (front), Warn winch, Snorkel, Dual spares , 160 litre water tank, 180 litre fuel in two tanks (approx 1200km range) 2010 Tvan Tanami. (incl another 70 litre water tank) with matching wheels/tyres (& 3rd spare)
A Nomadic Life (Blog)
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27th February 2021, 07:14 PM
#8
I am he, fear me
Once upon a time, cars, tractors, busses etc were either pos or neg earth depending on the manuf IIRC some old school Ford were neg but a lot of other yank stuff was pos and either was OK back in those days.
Pos earth grounding as a "norm" came from the early days of telegraphy where the vitals were Copper and Copper alloy (which is more noble than iron) so that meant the copper components were galvanically protected in a pos earth scenario so they didn't corrode as much and lasted much much longer.
Once silicon semi-conductor technology became viable it meant a lot of the electronic components had the -ve or cathode common to the case.
Because the case was also the heatsink it meant you would have to electrically insulate the case from ground in a +pos earth so that meant the heatsink was less effective and shorts more likely.
This meant it was much easier and cheaper for manuf to produce -neg earth vehicles.
Executive summary is that solid state semi-conductors were pretty much responsible the death of +pos earth circuits in vehicles.
Last edited by the evil twin; 27th February 2021 at 07:21 PM.
Dolphins are so smart that within a few weeks of captivity, they can train people to stand on the very edge of the pool and throw them fish.
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