Ground Wire Gauge

[Clerek]

I have ALOT of 18 gauge wiring, and was wondering if it matters what gauge the ground is. I am using some of the existing wiring(mainly connectors, for the ac, rectifier, and tci) and the ground is a bigger gauge. Also the old wiring looks like it is 20 or 22 gauge wire, and the new stuff I am using is 18. Does that matter?

So my questions are, for the ground, does it matter what gauge I use for the ground? Can I connect a smaller gauge ground wire, to a larger existing ground wire? And for the other, the older wire is a smaller gauge, and the newer stuff is a bigger gauge, does that matter?

-Rick

[CatatonicBug]

Think of wire as a garden hose for electricity. It runs in a loop. If the circuit comes in (positive) with a large hose (usually because of larger amps), it has to leave through a similar-sized hose, or the pressure will build up in the form of heat. Ground wires are often combined in circuits like these, and several smaller circuits are joined to one larger ground "hose" to connect to the frame and complete the circuit loop. As long as the circuit you are connecting FROM is running on smaller wire, it's fine. However, larger is usually better/safer when it comes to ground wires.

[Geezer]

I wouldn't use anything less than 14 gauge for the main ground wire.

Geezer

[TADracer]

My thought is that for ground wires, bigger is better. The ground is in the circuit after the load so there is no point in having a small ground that will add to the overall resistance of the circuit.

Not being a real electrical kind of guy maybe my thinking is flawed but on my 79 Special the main ground (or negative) wire back up to the battery is the same gauge as the positive out and it is connected to the frame. So I look at it this way, every electrical component is putting its residual current back into the frame through smaller ground wires. Add them all together and the wire that goes back to the battery needs to approach the capacity of the positive line out.

Well, at least it sounds good.

[audijunky]

All of the above are good posts, when in doubt make it bigger. There is nothing wrong with a wire that is larger, the problems begin when they are to small.

[Clerek]

Alright so I am going to go out and buy a bigger gauge wire for the ground. Thanks guys!

What about the other wiring? I just wanted to make sure it was alright...I am using larger gauge new wiring, and connecting them to the wiring just before the connectors. but only on the tci, starter, pickup coil, ac, and rectifier...everything else head/taillight, turn...are all on new wiring with the bigger gauge...

-Rick

[audijunky]

That will be fine also, as long you have good solder joints and heat shrink the connections, you gain nothing except a newer wire by doing this though, the larger guage does not help (but doesn't hurt either) when spliced to a smaller wire. Whats wrong with the existing wires?
FYI the starter wire should be considerably larger (stock wiring) than the other components you mentioned

[Clerek]

imagine the worst your wiring harness could get and multiply that by 1000... everything is wrong with it. melted wires, plus I am doing a bobber so I took off alot of stuff...I didn't want to mess with it so i decided to start from scratch...

Thanks!

-Rick