Electrical Help

Thomas, please read my post just before yours. I was writing at the same time you were.

IMHO, Mike gave you some very bad advise. Keep using the recommended circuit protection. You do not want a wiring fire.

IHTH, Matt W.

Hi Matt, we agree on many points about wiring and fuses.  I agree that fuses are there to protect against a wire fire due to a short.  I realize that my example used 50% more load as my fuse size for a particular circuit.  I'd like to clarify that that is my upper limit for determining what fuse to use in a circuit.  I typically use something around 30% for sizing fuses.  But to understand why I would use up to 50% load one has to look at the capacity of the wires in that circuit.  I've attached the wire gauge selection table that I use when building electrical features.  It addresses both 6v and 12v loads. 

Mike, If you are using the larger diameter wire, which is the lower numbered wire size, I agree you will be fine. 

You have the 12 volt system highlighted. However, Thomas is running a six volt system. IMHO, for the head lights, one should use at least 10 gauge wire. Unless Thomas is using relays that are not shown on his diagram, the entire circuit for the head lights from the battery to the elements is 10-15 feet. Now guessing that the high beam pulls 15 amps, 6 volt at 15', per your fine chart, means using 10 gauge wire. Which is what I use.

The headlights & the horn are the circuits that I would look hard at using relays because of their high current draw. This way a shorter high amp draw wire runs from the battery to the relay, which is close to the head lights, then on to the head lights. This wire should run about 4 ' long. Then the 15' could use 14 or 16 gauge wire.

Except the heater motor, the lower amp circuits could get by with the 14 & 16 gauge wire. The heater will require 14 or 12 gauge. Like you suggested, I would use the larger, 12 gauge.

BTW, your chart agrees with the chart in my aircraft standards handbook.

If I am out your way this summer & can find you at home, could I gaze at your Elecro-Willys? That is some contraption! I read that entire thread with joy. I confess that I have not read the entire thread on the Alaska trip. I get very busy in the summertime.

I do not know whether to be impressed with your Engineering degree, or should I class you with those "clueless educated idiots" that most of us mechanics cuss on a daily basis. Hmmm... I will choose to be impressed, as you are obviously at heart, a fabricator-mechanic.

See you then, Matt W.

 

Yes, I may have overestimated the length of the wire run.

One has to measure the length from the battery, through the fuse box to the light switch, down to the dimmer switch, then forward to the headlights via the fender mounted junction block. Just guessing, I come up with 4.5' from the battery to the headlight switch. Then another 2' to the dimmer switch. Lastly I figure another 4.5' to the lights themselves. That adds up to 11 feet. I am too tired & the Jeep is out in the north 40, so guessing will have to do for now.

I also want the information we give to be accurate & safe. To that end, "places where the wire is in danger of overheating" include near the exhaust, tucked up into the frame away from cooling air, in any conduit, & in any large wire bundle.

IHTH, Matt W.

Well done! That's a big job and easy to flub up. 

While replacement Willys smoke is hard to come by, Ford makes a suitable substitute that works quite well. Fortunately, it doesn't look you'll be needing any 

Sweet!  Mebbe I should see if you'd like to come to my place and rework some of my wiring messes.  You've done a great job and your attention to detail shows.  Thanks for sharing the challenge and the photos.