Chasis Resistance vs Copper wire

[Notladstyle]

There is a guy on another forum arguing that the chasis of a car is inferior to a 4ga copper wire as a ground.

He says that both power and ground should be ran the 17 ft to the battery for optimal conductivity.

For some reason I doubt that a copper cable with such a tiny volume/inch copper wire could conduct better than a massive steel chasis.

I know copper conducts better than steel but my issue is with volume of steel compared to copper. Theres just much more room and hence a lower resistance with the chasis.

Arguments?

[TJElite]

There is a guy on another forum arguing that the chasis of a car is inferior to a 4ga copper wire as a ground.

He says that both power and ground should be ran the 17 ft to the battery for optimal conductivity.

For some reason I doubt that a copper cable with such a tiny volume/inch copper wire could conduct better than a massive steel chasis.

I know copper conducts better than steel but my issue is with volume of steel compared to copper. Theres just much more room and hence a lower resistance with the chasis.

Arguments?

I've heard this before, too. Every time, though, it was not first hand knowledge, but rather based on some test, some famous audio guy did. I've also heard that it was at least 3 different famous guys. The most plausible story I heard was that it was all the welds in the chassis that added the resistance. Think of all the sheet metal being parallel resistors, and the welds being series resistors.

I've also seen grounds done both ways...to the sheet metal, and back to the battery, and both seemed to work fine, if done properly. I've also seen poorly made chassis grounds, where the person would have been better going back to the battery.

So what do I think? I think that there is nothing wrong with a PROPERLY made chassis ground. Nor is there anything wrong with a run back to the battery, provided the ground wire is at least as big as the power wire.

For a less experienced installer, I think that the run back to the battery might even be better, since it eliminates the possibility that they will screw up the chassis ground, and it eliminates the need to upgrade the factory battery to chassis ground wire.

Futher, except for the extra expense, time, and install issues (hiding second big wire) I would think that running a one size bigger ground back to the battery might be a nearly perfect solution for any install.

Will I stop chassis grounding though, probably not.

[Notladstyle]

how could a 4ga wire offer a lower resistance than a steel frame several times the wires size and volume?


do you have the equipment to measure that kind of stuff?

[TJElite]

how could a 4ga wire offer a lower resistance than a steel frame several times the wires size and volume?


do you have the equipment to measure that kind of stuff?

Personally, I don't think it does. Again, the theory I heard is that each large volume of steel is of lower resistance, but they are joined by high resistance welds. Kind of like a foot of 0 gauge, joined to an inch of 18 ga, joined to another foot of 0 gauge. I never said I believed it. But I also think the difference is probably on the order of micro-ohms, and really doesn't matter. To borrow from Richard Clark, its like asking which size screen mesh to use on the door of a submarine.

I used to have a micro-ohm meter at my old shop...not sure they still have it. I'll see.

Toby