Wire questions

[SilverHoot]

I'm going to completely rewire my trailer and the umbilical to RV industry standard configuration. It originally was wired with 10/2 aluminum wire for the 110 and 12v and I'm changing to copper 12/2 Romex for the 110 and 12ga stranded for the 12v. I do have some questions regarding color, gauge and type. I've found an online resource that I can buy either 25' or 100' spools of tinned marine wire. The 100' spools are about half the price per foot as the 25' spools. Originally there was green, red, black, blue, white, brown and yellow wires running from the umbilical. To further complicate things the white wire is a larger wire maybe #10 and the blue even larger yet maybe 8 or 6. Is it advisable to use all the different colored wire? It would be much less money if I were to use black and white for everything 12v but do not want to create a nightmare down the road if troubleshooting is required. The larger white wire looks like it connected to the battery negative(s) which will be about 20' towards the rear of the trailer in it's original location. The even larger blue wire will travel the same distance to the positive post of the battery. I plan to mount the converter within a couple of feet of the battery. So I could buy:
25' of 10ga white
25' of 8ga blue
25' of 12 ga red
25' of 12ga green
25' of 12ga brown
25' of 12ga yellow
25' of 12ga blue
100' of 12ga white
100' of 12ga black

Sound about right? Suggestions welcome!

[Jammer]

In general you want to use many colors because tracing and troubleshooting is extremely difficult otherwise.

It does help to number the wires using one of these:

Scotch STD-0-9 Standard Wire Marker Tape Dispenser

In general 12 gauge wire is heavy and difficult to run and should't be used except where the current carried requires it. 16 gauge is customary for 12 volt runs under 10 amps.

I would think that you should be running your 12 volt wire inside loom to protect it from abrasion. The 120v wire should be protected from abrasion also, using grommets where it goes through or over a rib, bulkhead, or other metal edge.

The marine places have 16 gauge paired and triplexed wire, kind of like romex, which reduces the labor considerably since you don't have to loom up the pairs and can just run the cable.

[SilverHoot]

Interesting the suggestion of 16 gauge wire, for some reason I have in my head that most people use 12 or 14 gauge. Mine originally had 14 gauge from the trailer plug to the tail lights, stop lights, and electric brakes. Maybe I should go with 12 or 14 for the tailights, brakes and running lights and use something lighter after the 12v distribution panel?

[Jammer]

To size the wire properly you have to know how many amps are going through it. A turn signal lamp is typically 2 amps, so you can use 16 gauge or even lighter.wire.

Tail and marker lights are a little over half an amp each but since you probably have 14 or more of them all together it adds u p and so the tail/marker circuit ends up being over 10 amps, so you want to use 14 or 12 gauge.

I ran #8 for the charge line and ground, #10 for the brakes, #14 for the running lights, and #16 for the turn signals on my last wiring project.

[SilverHoot]

Jammer,

Thanks for the input. I searched and think I found the thread that had me thinking 12 gauge was the way to go. Here it is: http://www.airforums.com/forums/f37/...ion-52264.html

Some additional information is that I will be changing most lights to LED so amps will be even lower.