Grounding Electrics Clarification

[PaRenegade]

PaRenegade, I like the detail in your system. What did you use to seal up the liqutight? Assuming its dogged off and siliconed,

At the end going into the box (Cantex 4x4) I used a LiquidTight connector and the other end, which isn't hooked up yet (still in mid build stage), I plan on using duct seal putty like is commonly used at the service entrance cable penetration. I'll terminate it under the battery and then put a drip loop right after it.

No toes stepped on here. Just passing on knowledge or methods I've learned of on my Jeep rebuilding journey. I'm no expert, especially when it comes to electrical or electronics. Curious though, if aluminum doesn't handle heat well, and distance builds resistance and therefore heat, why do they use aluminum for the larger service entrance cable and similar large gauge cables like the ones on poles?

 

[tarry99]

At the end going into the box (Cantex 4x4) I used a LiquidTight connector and the other end, which isn't hooked up yet (still in mid build stage), I plan on using duct seal putty like is commonly used at the service entrance cable penetration. I'll terminate it under the battery and then put a drip loop right after it.

No toes stepped on here. Just passing on knowledge or methods I've learned of on my Jeep rebuilding journey. I'm no expert, especially when it comes to electrical or electronics. Curious though, if aluminum doesn't handle heat well, and distance builds resistance and therefore heat, why do they use aluminum for the larger service entrance cable and similar large gauge cables like the ones on poles?

Pa............Aluminum is right behind Gold at #4 on the list of Conductive metals. But that really is the only "Good" thing about Aluminum.

Aluminum expands and contracts from heat when energy such as current is applied.........it also is prone due to this expansion to loosen fittings or joints along the path and requires further maintenance in electrical panels when high resistance occurs due to heat build up by loose fittings.............That in itself has caused more house fires than any other electrical malfunctions........ Furthermore aluminum is also prone to corrosion and oxidation of said joints and requires an anti-Oxidant joint compound at all connections.

And the reason that service entrance cables and other large gauge cables are aluminum...........well that answer is easy.......It's Cheaper & lighter than Copper...... Period!

On my Race car I use a stranded Copper AWM / AWG style Appliance wire rated for 105 C , nothing better made.........I also solder every fitting and seal them with a 3M heat shrink tubing that is 3 times the strength of normal heat shrink which also emits a fuseable sealing glue that seals the joint when heated. Look closely and you can see the shiny black material at each end.
No issues with the electronics even at 200 mph.

 

[gadawg31]

WOW, thanks everyone for the ideas. I think after reading and since I am not far with my tub assembly, I believe I will lift it back off and ad some ground points. This way I know where they are going and can route the wire properly. Again, thanks for the ideas.

JD

 

[jdarg]

If steel were such a good conductor of electricity why is wire made from copper?

Pure copper wire is not really used in automobiles, except maybe by the audio guys. Its almost always copper plated steel wire. Pure copper wire is way too expensive to use in pretty much any application (except maybe audio where guys swear they hear a difference in $800 vs. $0.80 cables and wire.)

 

[jdarg]

This is a great subject since most do not understand the absolute need for proper grounding on any 12v circuit.
As most have stated a grounding block buss Bar is a good Idea..........
Frame grounding , is still in use today but due to rust, dirt & corrosion and the fact that Carbon steel is near the bottom of the list of Conductive materials its no wonder that people have gotten away from it as a method to Proper Grounding.
Modern Cars today with electronic components everywhere have common ground points that have a "Direct Path" back to the Battery.
It should also be known that the Ground Path back should be of a current carrying capacity in wire size of at least 80% of the powered circuit's carrying capacity that it's grounding.
Furthermore if the return path is of any length the wire size should be enlarged over the distance to eliminate resistance and heat build up. In fact most will measure there ground paths back in Ohm's..........shooting for the least resistance!
Also Stainless steel is lower than Carbon Steel on the list of the best metals for conductivity.......with Silver being #1 then Copper and Gold at number 2 & 3.

I respectfully disagree with some of your statements. They are misleading.

What's an example of a modern car that has a "direct path" back to the battery? I have a 2013 vehicle that uses the same grounding strategy as my 1975 CJ5 , so I'm curious who does this?

Do the same electrons not flow equally through through the + and - of a circuit? Why would you then underrate the ground side 20%? What if I reduced the + wire 20% instead? Are you suggesting there's a difference and the device would know the difference? I think this is a textbook rule of thumb where the assumption is the ground is MUCH shorter than the B+ so just be careful with that.

The resistivity difference between carbon steel and stainless is on the order of .000001. Even gold vs. carbon steel is just another zero where there are already lots of them. Do you think you measure a difference in our particular application - same gauge wire, different materials - where no circuit probably exceeds 15-20' total, end to end?

I get that you guys like your buss bars and all, but you are using meaningless facts and inaccuracies to try to convince people. Saying silver is #1 and gold, etc. is #2 and 3 means nothing for a short run of wire in an automobile. These aren't Transmission lines we're talking about. The frame will have far more cross-sectional area than any wire you are going to use, so it has the best current carrying capacity and least resistance per given distance. Resistance = heat which is what we need to avoid. I agree frame connections will degrade over time, but this is no less true for copper. Paint the connection. It will help slow that reaction down a lot.

 

[cj7inthetwigs]

Yall get me wondering if I should consult my electrical engineer buddy before turning the key to "on".. Pa, you sound like your either electical or maintenance. Aluminum is cheap,thats why. Stranded copper is best,period. How you get there is up to the individual. I'm by no means saying anyone is wrong and opinions are well you know. Just because a automobile manufacture does something,doesn't always make it the best viable option for said application. Frame grounds work? All day long! The devils always in the details.
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[PaRenegade]

Pa, you sound like your either electical or maintenance

Nope, just a mechanically inclined tinkerer. "Jack of all trades, master of none"
I design homes for a living, so I'm more of an engineer type.

"Just because a automobile manufacture does something,doesn't always make it the best viable option for said application."
Couldn't agree more and that's basically all I'm saying. I'm just improving on a 30+ year old AMC system.

 

[Old Dog]

The only thing I can say is that with my glass body I started by grinding a clean spot on the frame and grounding the lights to the frame. They were not very bright. I than ran ground wires and bingo I had good lights.

 

[tarry99]

I respectfully disagree with some of your statements. They are misleading.

What's an example of a modern car that has a "direct path" back to the battery? I have a 2013 vehicle that uses the same grounding strategy as my 1975 CJ5 , so I'm curious who does this?

Do the same electrons not flow equally through through the + and - of a circuit? Why would you then underrate the ground side 20%? What if I reduced the + wire 20% instead? Are you suggesting there's a difference and the device would know the difference? I think this is a textbook rule of thumb where the assumption is the ground is MUCH shorter than the B+ so just be careful with that.

The resistivity difference between carbon steel and stainless is on the order of .000001. Even gold vs. carbon steel is just another zero where there are already lots of them. Do you think you measure a difference in our particular application - same gauge wire, different materials - where no circuit probably exceeds 15-20' total, end to end?

I get that you guys like your buss bars and all, but you are using meaningless facts and inaccuracies to try to convince people. Saying silver is #1 and gold, etc. is #2 and 3 means nothing for a short run of wire in an automobile. These aren't Transmission lines we're talking about. The frame will have far more cross-sectional area than any wire you are going to use, so it has the best current carrying capacity and least resistance per given distance. Resistance = heat which is what we need to avoid. I agree frame connections will degrade over time, but this is no less true for copper. Paint the connection. It will help slow that reaction down a lot.

Jdarg...........All the information supplied here is factual and of good sound electrical advice to establish some level of redundancy in there 12 v system along with hopefully helping some correct the same mistakes that others make daily on there wiring.

Picking apart information to suit your needs is OK by me but suggesting that anyone else should continue to use the same methods that caused the problem in the first place is a real waist of time.

The pages of these forums are filled daily with people addressing wiring issues created by either sloppy installs, loose fittings ,grounds and or corrosion and lack of maintenance ........some may choose to use some information contained herein to enhance there install or at the very least get a better understanding of the complexities of a well designed redundant 12 volt system.

Perhaps you should add some helpful solutions here other than suggest that all should continue down the same old path!

 

[PaRenegade]

Well I'll say this. Information garnered on the internet can go either way and the more things are repeated the sharper that double edged sword can get. (for instance, take the AMC20 ) So do your own research and make up your own mind.

But think about this. It's a pretty commonly excepted solution on Jeeps and several older vehicles to do a headlight circuit upgrade to get brighter headlights. It's done by basically replacing the pos+ sides wire with new larger gauge wires directly to the lights (via a relay) and using the old wire to operate a low amperage switch (the relay). And those lights are then noticeably brighter.
So if increasing the pos. path between the battery and device helps provide more juice, wouldn't it stand to reason that doing the same to the neg- sides wire would also improve current flow? As was said above, the same electrons are flowing equally down both sides.

 

[cj7inthetwigs]

Electricity is alot like plumbing, lesson 1 in electrical theory.

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