Stupid Question #2: how does an iron frame act as a ground on our cars

[ericr]

-or any car, for that matter. but I'll bet some of us have wondered about this.


our cars are DC of course, meaning, apparently, that there is a constant flow of electrons through the system when some application is using electricity. how can a frame of iron/steel act as a successful conductor for one pole of the battery?


We don't associate iron/steel as being a significant conductor in other contexts....how can it be successful in electrical transmission on a car?

[Jacksonlll]

The structure is so big there is very little losses. No reason to use silver or copper. It’s just another big wire.

[Railcarmover]

One thing is for sure,a ground strap from the battery to the frame and from the frame to the driveline is critical if you don't have splash pans.

if you don't believe steel is a good conductor then you haven't had a full childhood..

[Bruce of MN]

Originally Posted by Railcarmover

if you don't believe steel is a good conductor then you haven't had a full childhood..

Hah, that's pretty good!

[History]

Originally Posted by Railcarmover

if you don't believe steel is a good conductor then you haven't had a full childhood..

Or peed on an electric fence.

[aermotor]

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No problem according to Myth Busters.

John

[Bill G]

Steel and iron are excellent conductors of electricity. The frame is used instead of running a "common" grond wire. It was a pretty common practice back in the day and was part of keeping the cost of cars down. Separate ground wires are better, and used a lot more on modern cars because so much of new cars are made using plastic parts which don't conduct electricity.

[Mike V. Florida]

Originally Posted by Magicbox51

Steel and iron are excellent conductors of electricity. The frame is used instead of running a "common" grond wire. It was a pretty common practice back in the day and was part of keeping the cost of cars down. Separate ground wires are better, and used a lot more on modern cars because so much of new cars are made using plastic parts which don't conduct electricity.

Not just "back in the day" but even today. imagine the cost, weight, and complexity of running two wires to every single part of a car that needs electricity. I'm not saying there are no components that use two wires but there are a whole bunch that do not.

[johnbuckley]

this is fun site for checking voltage drop and resistance https://www.rapidtables.com/calc/wir...alculator.html

[Patrick L.]

AH, so thats why I feel all tingly whenever I get in the car !

[ericr]

Originally Posted by Railcarmover

One thing is for sure,a ground strap from the battery to the frame and from the frame to the driveline is critical if you don't have splash pans.

if you don't believe steel is a good conductor then you haven't had a full childhood..

Not so....you know what they say about Dad and Mom being in the iron and steel business.

[Cool Hand Lurker]

Don't look on it as a "ground", look at it as a big conductor hooked to one side of the battery. The critical factor in completing a circuit that works lies in the quality of the connections to the conductors between the battery and the component to be powered. Clean connections will make good contact, dirty or corroded connections may not let the current through.

[holdover]

Steel works pretty good, that is how power gets to your house

[Railcarmover]

'Sand Pebbles" with Steve McQueen.. Master Chin,head coolie of the engine room said there are wizards,wizards in the engine....

[ericr]

well gang, I confess I fibbed a little bit. I read in my book about Henry Ford and the D T & I that when he bought the line, it had iron telegraph wires, but they had corroded significantly.


But if iron is an acceptable conductor, I don't see why it doesn't replace copper, which the US is not well-endowed with.

[Patrick L.]

I'm not sure I would want a frame of iron, I prefer steel. I really don't think I'd want one of copper, even if it could be afforded

[jrelliott]

Note to ericr, Arizona and a lot of other states have abundant supplies of copper. EPA and OSHA and other agencies have made it difficult to mine cost effectively. Smelters put out a lot of undesirable byproducts. Cant get a mine open near Superior, AZ as it is on a sacred site per the native americans.

[Railcarmover]

The perceived dearth of American copper was magnified during WW2,all copper available was diverted to the war effort. Some interesting things about that...we all know about the zinc penny in '43..but did you know the calutrons used to enrich uranium for the bomb used electromagnets wound with pure silver? it was 'borrowed' from the Treasury,and had to be accounted for to the ounce..


Mining and smelting capacity increased by the end of the war,we began using our vast reserves of copper ore..we are currently 4th in the world in production.

A German would appreciate that,they were on the receiving end of most of our copper..

[Jim Brierley]

Steel or iron isn't used as wire for the reason stated, it corrodes, rusts, easily.

[rotorwrench]

A lot of metals can be used as conductors but some are definitely better than others. It's all about resistance or the need for very low resistance levels. The longer a conductor the higher the resistance. Steel and other ferromagnetic related alloys do OK but corrode easily as already mentioned. Aluminum and copper are the least expensive of the metals that make good wire. Silver and gold are much better but obviously much more expensive. The alternate is to plate wire with tin, silver, or gold to reduce contact resistance. With gold being so very expensive, it is limited to plating for terminal pins and sockets so as not to break the bank. Aluminum wire has to have a larger cross section gauge to replace copper but it is used a lot in power transmission wires we see on the side of the road every day. Aircraft wire is available in silver plated copper for better conductivity or tin plated copper for better corrosion resistance. Copper is king in the automotive business with tin plated copper as a more expensive alternative to bare copper.