Technical How much wire needed to wire a car?

What gauge wires does American use?

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8 Gauge feed & alt wires, colour coded 12 gauge wires labeled every two inch.
link to the kit http://www.americanautowire.com/view-product/highway-22-complete-wiring-system/
very easy to follow instructions and a large full wiring diagram.

 

Does the engine or interior/light wiring cause the most shorts/fires?

 

14 ga is plenty for lights, etc...I guess if you went to those high intensity bulbs, you might want bigger wire, but look at the wire used in 12volt systems through the day before relays were the norm, I think the headlights in my '57 Chevy are 16 gauge, that 50 dollar setup from ebay will be fine for most any applications, of course you'll need larger wire for charging and to feed the box, but 1 25 foot roll should take care of that.

 

I believe my Kwik Wire lighting wire is all 14 awg. I have halogen sealed beam bulbs up front and they're quite bright.

 

Waitaminute....someone calculated their jobs to the decimal?

Sure hope slack was left in certain areas.

sent from my toilet

 

If all this wire is under rated (as stated above) how does one know if the things it connects to are safe to use?

 

Forget about it.
Just Farm the wiring out and be happy

 

Cheaper to buy a harness
or a good book on wiring
or a harness
and like my man above mentioned (#36), don't cut things short to make it look "neat" and screw yourself
Harness? Why, yes, thankyou.

 

Great info. Thanks a million!

 

There's two things to check for when sizing wire; one, is it big enough for the load? Fuse the wire for it's rating, and it's safe. The second thing has to be calculated. Wire length can have a large affect on voltage drops, even if it's sized for the load. A wire that's adequate for both the load and voltage drop at say, six feet in length, may have an unacceptable drop at ten feet. And you can have different drops depending on what's in use.

Most kits mimic the OEM type harnesses as to wire size, but the trouble with that is the OEMs don't put anything more than absolutely needed into their harnesses as it would increase costs by a few bucks per harness. Multiply that by several million cars and you're talking real money. And they're willing to accept up to 10% voltage drops, which is enough to have detrimental effects on many circuits. That Autowire wire kit is one of the better ones, but note that only the 'power wires' are #12 AWG, meaning there is smaller wire being used for other circuits. And the #8 panel feeder, while bigger than the typical #10 you usually find, still probably won't be big enough if you have a lot of loads.

 

Ok, Without using Battery Cable can you just step up and state what the OVERKILL size wire gauge is? Not that I'll ever wire a car but the BS gets real old. Bob

 

A mix of 14 and 12 for the most part will do the job. use the thicker for high draw applications. Think of these as anything that connects something mechanical like electric motors or something that produces heat like heaters or anything with a heat sink like amps etc Easy way to figure out is if the fuse is hmm 20 or 30 amps or higher use a thicker wire.

 

Here is a wiring diagram for a 1952 6 volt dodge pickup. We know wire needs to be heavier for 6 volt.
They used 14 for low beams and 12 for high beams, 16 for parking lamps.
Someone above said they thought 57 used 16 gage headlights.
My original 68 year old cloth wiring is in actually pretty good shape. The head lights work fine along with horn and heater. I would say this is over kill, and if you are 12 volt, way over.

 

There is no standard 'overkill' size; what would be overkill on a bare-bones Model A coupe could be totally inadequate for a '59 Caddy with power everything and a set of air bags. If forced to give a guaranteed 'overkill' size, I'd go with #2 for the alternator and fuse panel feeds, and #10 for everything else. But this would be ridiculously oversize for most cars, which is why it's so important to calculate each circuit. The problem with the kits is they give you a 'typical' wire size for that type of circuit but usually use the low end of the range scale when selecting the wire.

Any time you have a short or fire in a harness, it'll be because of a failure in at least one of these things; design, installation, or workmanship. A harness designed and installed right won't have these problems...

 

I did my 56 Victoria with a REBEL KIT!

 

Yes, while you are technically correct, it appears the only options you are offering are 1-have the car wired by an automobile wiring spe******t (none in my Yellow Pages) or 2- buying a lot of different insulation color wire, learn to properly attach the connectors, guess at the proper relays and breakers/fuses to use and figure out how to make it all come out nice and neat. Neither option really sounds practical or affordable for a backyard builder, so what do you suggest?
FWIW, there are 4-6 well known wiring harness suppliers and likely 1000s of cars on the road using their harness kits. Are they all wired incorrectly and unsafe? For that matter, there are roughly260 million cars on the road in the USA and I am betting virtually all of then have wiring less than 14 gauge.

What's the practical solution?

 

This may be a good time to show up at my place with a trailer and CASH. Bob

 

Well, here's a good start.... https://www.jalopyjournal.com/forum/threads/wiring-101.843579/

It never ceases to amaze me that guys will spend all the time needed to select/adapt/install the mechanical components and ensure that they work well together, yet will buy a 'universal' wiring harness and give zero thought as to if it's really adequate for their vehicle. Will it be more work to make sure the harness is done right? Yep, it will be. But would you cut corners on your brakes, steering, suspension? Yet the wiring harness is the nerve center of your vehicle; there's almost no limit to the number of issues a poor harness design/install can cause, and a single catastrophic failure can burn your car to the ground.

 

How much?

One pre-made harness.

 

I have used three different brands of wiring harness. Ezy wire, some Ebay china **** and American Auto Wire.

This current build will be my second time using AAW. Its good heavy kit with great support for those custom things you may want. Want to know where to plug the air pumps into, plug the XYZ doo dad into then ask them and they will flick back a modified schematic.

After one of the above comments that it went smaller I got the kit I have sitting on the shelf down and checked. yes some of the wires drop to 14g. But for the load they are taking its fine and is thicker than what other brands offer. The fuse box connectors all are made for 1x 12g but can fit 2x 14g if needed.

I agree with Crazy Steve about dont cut corners to save a penny when it comes to wiring. But some of the kits out there are better than some of the auto electrician jobs I have seen. And christ I have seen some real homer simpson head desk jobs done by some shops who charge a pretty penny.

Do it once do it right. If you need to wait an extra month to save a few bucks to get something that will handle the load whilst offering easy install and future electronics proofing then wait. Wires labeled every few inches actually make the job pretty fun.

Auto electrical fires aint funny. Good earths & good wires along with the right fuses & relays coupled in with common sense.

 

Good response. Thanks.

 

I just finished wiring up my '29 roadster using the Speedway Motors 12 circuit harness kit. It was pretty straight forward and well labeled making it easier to track all wire routing. I had to do a little figuring on my own for some things but overall found this to be the best solution complete with fuse box. Having worked in the automotive wiring business for many years I did not find any circuits that were undersized for the intended job. because the wires are pretty long to begin with I was able to shorten them to fit my model A body and chosen routing. Everything works and no real problems yet. Not promoting the brand here but I do feel that buying a pre-made harness with fuse panel is the best way to go unless you really enjoy making one from scratch or can pay the man to do it for you.
Bob

 

I also used the Speedway harness, but I went with the 20 something circuit one because I plan on AC later on, plus I already had power windows. Even as long as the 47 Lincoln is, I still had plenty of wire back to the tail lights and forward to the headlights. I've got several circuits still unused for when I add the things I want, AC, a good stereo and amp, interior lighting, etc. Better to have them and not use them than need them and not have them as far as I'm concerned.

 

That's a GOOD response.
Should be a sticky

 

It's EXTREEMLY difficult to cover wiring information with blanket statements. Using words like "properly" should not be allowed because the word actually refers to volumes upon volumes of super dry technical information and there are still exceptions to that information. Instead of "properly" a citation of the 10 chapters where that info is spelled should be given. Most guys don't read, that's why they want a blanket statement.

 

I used a Kwik Wire kit in my Ford and everything was good from the kit quality to the instruction book. The 14 circuit harness only had about 55 wires in it. I just recently used the electric fan circuit and have yet to hook up a radio. The Rebel 9+3 is probably comparable.