It’s been 5 years since my last electrical engineering class. And I know you guys know everything anyway!
In general when dealing with power/ground wires, your looking for wiring that will maximize conductivity, right? It was my understanding that the more solid the wire the better, right? (Of course I guess thins depends on you definition of “better”)
So when looking at a 4 gauge wire there are several different kinds that you find.
You have your 4 gauge wire from Lowes that is actually made up of about 10-12 strands of what looks like 18 gauge wire.
Then you have some 4g wires that are made up of 10-12 strands made up of 30-40 strands of tiny tiny 40 gauge (or whatnot) wire. This wire is much more flexable, but which type delivers the best properties that would be optimal for your cars ground/power? Even in a souped up Honda, would it really matter?

 

The stranded wire has the same conductivity as solid-core wire. The stranded wire is commonly used because it more flexible. A solid-core 8 or 4 gauge wire would be impossible to bend in the small areas inside an engine bay. Solid-core wire is used in home wiring because it is cheaper to make, it holds it shape more (useful when running from floor joist to floor joist), and the need for tight turns is not so great. I hope this answers your question!

Mr. Shifty - Who has an electrical engineering class tomorrow morning at 9:00am

 

There has been a lot of talk on grounds here, now I guess I have to put my two cents in. All #4 wire is Not created equal. It is equal from a DC perspective, but those grounds also provide grounding of high frequency content riding on the DC. To ground RF you need braid, and lots of it. For those of you that want to look into it, look up the skin effect and how RF (high frequency content) only travels in the skin or outer layer of a conductor. Hence braid maximizes that surface area. For those of us up north, salt plays h*ll on that braid, and can corrode the snot out of it in 3 or 4 years.

You will notice most stock applications have at least one or two braid grounds for the RF, and then a cable type ground for the DC starter current.

A little insight into EMI/RFI. (Electromagnetic Interference/Radio Frequency Interference.) One could write many textbooks on it.

I like to see at least one good braid ground (3/4 inch wide) from the block/transmission to the chassis. With star washers on both sides to bite into the braid and the block and the sheet metal and the braid on the other end. This helps to keep all those nasty spikes from ignition, fuel injector pulses, etc. away from the sensor leads and the ECM.

Regards,
BigMoose

 

So for an automotive application, you want the "4g wires that are made up of 10-12 strands made up of 30-40 strands of tiny tiny 40 gauge (or whatnot) wire", correct? And it's not just easier to bend, it's all about surface area. (sound of light turning on insert here)

 

Correct! What you want is the 4 gauge wire that is made up of a lot of small strands. If you can't get braid, use some class K welding wire. The specifications I have handy show #4 welding wire at 406 strands 0.010 inch in diameter. Thats a nice wire, or #2 at 651 strands of 0.010 dia. No need to go any bigger. Welding wire is what is used on the secondary of Arc Welders. For comparison #4 battery cable is only 49 strands of #21 wire. Great for DC, not so good for RF. I buy my wire, connectors and such from Waytek wire, great prices and service. 1-800-328-2724 www.waytekwire.com But you can go to any welding supply to get cable and stake-ons (crimp connectors).

You are right it is more about EMI/RFI than flexibility, though flexibility has a role in it as copper work hardens with bending and will fracture eventually.

Regards,
BigMoose

 

Thanks for the link!!
And the info!