Ok, so looking under the dash and the wiring looms it looks like Ford used 14 gauge wire, is that correct? I’m getting ready to install some gauges and my consolette building the wiring loom out of 18 gauge wire. Just seems odd that Ford used such thick wire. Maybe it’s just the casing that’s thicker? Anyway, I thought it was interesting and that somebody on here would know.
I found it to be 16 AWG in a 14ish sized shielding for extra heat protection. I wouldn't use 18 though, it will exude a bit more heat and that's not a good thing behind a console. When the wires heat up it affects the control signals and makes your gauges read off a tad. I used a nice 16 AWG wire with a high heat shielding on it better than the stock wires, and the shielding material they use now is much thinner than what was available in the 70s. As a matter of course I rarely use anything smaller than 16AWG in a car. The occasional amp spike from high RPM acceleration in already noisy systems is a recipe for igniting smaller wires on fire. That's not to say you shouldn't use the right wire for the job, just be prepared to be in line regulators to keep the heat thresholds down. When I did my LED dash I used all 20AWG wiring, but I put a lot of line conditioning on that circuit to keep it from ever going over 5V 2amps. Almost every wire so far I've checked in both the comets I owned, was actually a smaller wire than the shielding implied by measurement. I haven't cut open EVERY wire under the dash though by far.
I think I’ve been working on computers to long, 14 gauge wire looks like bratwurst to me. No worries, that's why I double checked. I Appreciate the input!
I'm a sasquatch everything looks small to me; but I helped run out some high tension power line once and that was one of the most frightening jobs I've ever worked.
The gauges better not draw enough current to actually need anything larger than 22-24 wire(still that's huge)... Of course if you decide to feed something else, 14 would be a good idea...
I always assumed they just didn't want to buy that many types of wire. Then I was pictures of a 68 mustang with a 3rd Gen alternator upgrade and a hack job rednecked dash upgrade to digital gauges that went up in flames because the 20AWG wires couldn't keep up. They SHOULD have been fine I thought. Then I remember the dash harness is only on like a 10-20 amp fuse, and if there was a big enough transient from the 115amp alternator he put on, it would probably flash-fuse the fuse to closed and then ignite up the smaller wires pretty fast. If you are all stock, smaller wires would probably be fine. If you have an upgraded alternator you might want to stick with wires that can take a beating from your alternator. Or like I mentioned before, make sure you have beefed up the line conditioning (fuses, Voltage Regulators, breakers) to more modern standards. It really didn't hit home to me until the cable house I used to work for had to fulfill an order of wiring harnesses(with a fuse block section) for some old military trucks, but the way those harnesses were made, to the way the harnesses for the same vehicle 20 years newer was configured. It was eye opening. Code: Gauge 110V 12V 22 5A 5A 20 7.5A 8A 18 10A 10A 16 13A 20A 14 17A 40A 12 23A 60A 10 33A 100A 8 46A 150A quick reference chart, it's like super vague but gets in the ballpark. (also, this chart is HIGHLY conservative, the chart in my engineering manual has higher values for the max amperages, but it also includes the distance those values are at. This chart supposes you may want to run a 20 foot wire for some ungodly reason without burning your car down around your ears.) From what I was told for designing cable harnesses, every wire in a circuit(there can be multiple circuits in 1 harness, the biggest I've built had 120 circuits) has to be the same size; every wire on a ground point should be no smaller than half the size of the largest wire, and the sum of the wires should be 25% greater than the total load on the ground point. Also, the smallest wire size you can use in the harness is dictated by the total average load across the harness, I estimate the Mav/Comet wiring at whole to be about a 20A average load.This is where you get into the most trouble and why you find so many oversized wires in (older)cars. I actually forgot the most important reason you have to use larger wires under the dash. You might want to be able to run your heater without impacting your wiring. It's easy to forget, but running your heat will heat up the entire underneath of your dash. I only remembered that because my brother-in-law got caught by his boss forgetting about that a few months ago. He's currently working at Freightliner (or Daimler Trucks North America if you wish) doing fault analysis engineering, and was diagnosing a problem with an aux-power harness to close to a heat duct overcharging cell phones plugged into it.
Pre '70 Ford vehicles generally don't have fuses or even fuse links to protect the harness... A good short meant you were replacing harness if not the vehicle...
