Making a wiring harness

[lostviking]

You can find many online calculators for amperage rating for wire gauges. The one thing to remember is Ohms law, it's online also if you don't work in electronic as I do. A stock system is 6V. That means the current in each conductor is twice as much as an equivalent 12V system. That is why the wires in our vehicles have such heavy seeming wires. They do. If anyone converted their trucks (or cars) to 12V, the stock system is more than adequate.

 

High strand count wires costs a lot more than the more standard wires you usually find. They are generally overkill for an automobile. Take a look at Atlas wire and you can find all the information you will ever need to get the job done right. Belden is another manufacturer, but we tend to use Atlas these days where I work.

[47Jim]

Here’s what I did for what it’s worth, all stock 6 volt with a one wire alternator and no more voltage regulator being the major change plus all the switches are new and generic, diagram includes wire gauge and numbers that correspond to the turn signal switch diagram 

bought the wire from Tons on eBay, fuse panel on Amazon, I located the panel where the VR used to be 

 

I replaced it one wire at a time because it was a custom harness and much easier for me to figure out, hopefully this will help a bit 

[John-T-53]

Rhode Island wire sells schematics for making harnesses. Check that out. I got a few for the future wiring project on my truck. They also sell wire and connectors. 

[Eneto-55]

Here's a bit more on strand count & gauge, along with a question.  (I know I'm in the PU forum, so maybe the question won't apply.)

 

On my P15, here is what I've found:

 

Gauge     Strand         Strikers

                Count

--------------------------------

12              41                  3

14             26                   2

16             19                   1

 

These wires are for the front lights,

12 ga for the high beams, 

14 ga for the low beams,

16 ga for the fender lights.

 

This all matches the gauge info given on the wiring schematics for the later models.  (The P15 diagram doesn't include any gauge info.)

 

Here's the odd thing, and the question: The actual headlight harnesses (what goes from the terminal block on the left side radiator shield up to the lamps) is different.  On those, the high beams are 14 gauge, and the low beams are 16 gauge.  I have those harnesses for both my 46 and my 49 1st series, and there is no difference, despite the difference in manufacturing years, and despite having been built is two different plants.

 

So, is there a technical reason why the lower gauge wiring could be used on those from harnesses?

 

[lostviking]

Well, if you are talking about the wires from the junction to the lights being smaller than the wires from the switch to the junction...the wires TO the junction need to handle both lights while the wires to the lights only handle the current for that side. Hope I understood.

[Eneto-55]

29 minutes ago, lostviking said:

Well, if you are talking about the wires from the junction to the lights being smaller than the wires from the switch to the junction...the wires TO the junction need to handle both lights while the wires to the lights only handle the current for that side. Hope I understood.

Well yes, of course.  I don't know why that didn't occur to me.  Thanks.

[RobRobitaille]

I have no experience with them but have you considered a Painless wire harness?  Obviously if your looking to keep things original looking they are not the way to go.