I need a length of the fatter red wire from a wiring harness ‘72 and earlier. This is NOT the main cable from starter to + on battery, but rather it’s from up around the fuse panel and thru the harness to the back (later cars do not have the fatter red wire, they went to 4 slightly thinner wires, fyi). 5-6 ft would do, anyone have any extra to sell? LMK, thanks.

ps- I’m extending my battery connections to the trunk and already have extra of the thinner red.

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You are welcome to come over and dig through my boxes of used wiring to see if I have what you need. I have about 4 harnesses that I am parting out.

Clay

Thanks Clay, I'm now starting to consider sourcing a full length in bulk and avoid a splice. I may have to ring you up for it though. I mean, I will be splicing the smaller reds too (or source some of it at the same time). A splice done well, shouldn't be a problem.

Anyone know the gauge and type needed? I think it might be 16ga but also there's various wire designations (ex. TXL, etc), another reason I was leaning to just do a splice with stock wire..

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Here's an aftermarket option: https://www.waytekwire.com/product/general-...-91a-automotive

Chris

Thanks Chris - but a 500ft minimum ain't gonna work

It looks like McMaster-Carr has what I need, 25ft for cheap:
https://www.mcmaster.com/products/wire/wire...esignation~gxl/

LOL, yeah 500' is a bit much.... If McMaster-Carr doesn't have it, you normally don't need it..

My only reservation is that McMaster-Carr list this 16ga wire as being .11" OD, which (according to google) is only around 2.8mm.

I get around 6mm when I measure OD with calipers, so what's that about

Can someone verify the 16ga designation of the heaviest red wire in an early harness?

Extending an existing battery cable, you may need to re-engineer the cable. As it gets longer, resistance and ampacity are effected. I'm not an EE but maybe someone else here is. You may need to upsize the cable.

When I moved my fuel pump up front I used these guys. https://www.sherco-auto.com/
They will sell in small lengths (I bought 25' of each) or 250-500+' big rolls. Like you, I wanted to avoid splicing with multiple connectors and I wanted the correct black with red stripe power wire and brown ground colors, everyone thought I was nuts, but I like to keep things as original as possible. They offered a lot of colors, gauges and material types.
Hope this helps
Mike

Thanks for the tip, I may need to ask over in the garage - lots of people have moved the battery to the trunk, so maybe there's a concensus on extending the cables.


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Every time I've moved a battery and ran extended cables the best bang for the buck has been cables for welders. The individual strands are much finer and there's twice as many in a welding cable versus a "battery" cable. It's about the same price as battery cables with twice as many conductors.

Current thinking (pun intended) is the electrons run on the surface of the individual strands and the finer the strands are the more amperage you can run.

All of the super high end stereo stuff has angel hair conductors. Thousands of them...

Thanks Mike, I'll keep that place in mind. My immediate challenge is determining the actual diameter of the big red wire. I'm starting to think it's actually an 8gauge (not 16 as I'd linked to above ^). So what they call "primary" wire, which is like all the other wire in the car seems to only go to 10gauge (too thin). So, then my option is 8gauge battery cable to run the length of the car - it measures the correct .22"/6mm, which is still thinner than the 4gauge that I'll be sourcing for the starter to + terminal on battery (that's another bridge to cross later).

You can see why a splice with used OEM wire looks attractive tho

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You can see why I was/am considering doing a splice with used OEM wire.

Audio applications use highly stranded cable to provide high frequency Eddy current flow on the conductor surfaces. Ergo stranding. It's for frequency response & not current capacity. Your application doesn't require this. A solid conductor cable would work, but there's no flexibility. I think a 10 gauge stranded cable will work just fine. I have an old wiring harness that anyone can borrow for donor sections. Just cover the cost of shipping. BTW, cable length is really irrelevant in terms of circuit performance since the lengths are so short. Cheers!!!

Hmm, Home Depot offers 20ft of this for $23 ! I like it because at .31" OD it's slightly thicker than the original fat red wire in the harness (this covers what @JeffBowlsby was suggesting about a possible need to increase wire size with distance), and it's still a little smaller OD than the main battery cables. I think I'll give it a try and forgo a line splice.

https://www.homedepot.com/p/WindyNation-8-G...G-20R/319417911

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That's a good price for that.

I'd have never thought of HD for cables, I'd have gone to a welding supply house and paid more...

I will NOW check HD the next time I need some. Thanks for sharing, Literati!

I've never seen welding cable with thick individual conductors.

Even their little picture says, "fine stranded for high amperage".

The sheathing is usually tough as nails and seems to last a long time.

You can get long lengths if you need it as well.

Start screwing around with a 50" motorhome and this stuff becomes more important.

A 50-foot length is under a dollar a foot.

Be careful what you buy new. Not all low voltage wire is rated for automobile use. Automotive wire has to exist in a harsh environment of oil, coolant, heat and cold extremes and vibration. If it is really cheap, it probably won't last in a car.

"Even their little picture says, "fine stranded for high amperage"."

This is total BS. How many strands are in the conductors in 8 gauge Romex for the 50 amp circuit that feeds your oven?

I hear you guys, but this cable is described as [i]“dual use approved welding cable and battery cable”. I’m not seeing it quote a regulatory standard, but considering I’m not even going to be using it for main battery cable and it’s going to be encased within a fully wire-packed jacket on top of its own protection, for the brief length it runs thru the engine compartment, I’m thinking it’ll be fine. Worst case scenario I may have to add a heat sleeve to the wiring harness that goes thru the engine compartment to the rear trunk firewall.
My main cables will be something else, unless I’m really impressed with this stuff, in which case I could order 4 gauge.

Edit: found this : ASTM Compliant, IEC Certified, ROHS .. also 55 amp max and 575v , UV resistant, 1.78mm jacket
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A quick Google search "DC wiring many strands versus few strands" brought this up as the very first thing at the top of the page.
I cannot find a direct origin of this quote however.
This is what I have been taught, I have no direct scientific proof of this, and it may be BS as Windforfun insists.



"In DC, electrons actually move down the wire, and actually mostly move on the surface of the wire. So having a lot of strands in the wire gives a LOT more surface area for the electrons to move. The wire with many strands is a lot more flexible as well."



I was enrolled in the A+P program at Tarrant County College and the instructors were adamant that replacement wiring had to have the same number of strands or MORE.
They were quite bitchy about that. I didn't think of questioning their advice.
Their reasoning was the same as the Google quote.

There is a huge difference between AC power and DC power and the wiring should not be directly compared. It's apples to oranges in my book.

The aircraft world is hugely rooted in the past and any new thing is looked at with a jaundiced eye.

They rolled a Porsche/Mooney engine into class one day and advised everyone that this was a fairly complex and intricate FI system and new technicians shouldn't even think about touching these at all.

It was an old (no longer emissions compliant) CIS system, and I shocked the instructors with my knowledge of this system. I did advise every single VW rabbit, a bunch of Porsches, a shitload of Volvos, and countless other European vehicles came with this set up as far as two decades ago (this was early 90s). The one they had was the very first fully mechanical version and later versions of this same system were far more complex and worked better (Lamda control).
They had the dead ass simple version, and it was not nearly as complex as they made it out to be.
My comment regarding it was "Porsche had a bunch of these left over that they couldn't sell on a car nowadays and they pawned them off on the aircraft world".

I taught the class that day...
I was far more experienced with CIS than anyone else in the building.

I'm not trying to argue with you Wind, but you are the ONLY guy to ever have a problem with this. I have accepted that a wire with more strands is better than a wire with fewer strand for DC wiring.

I've used welding cables many times, have installation that have been in use for decades, and have never had an issue with them. The quality is often better IMO than "automotive" grade wire.

I would add fire sheathing to anything running close to a heat source automatically.
Doesn't have to be wiring.

If someone has real data that shows the number of strands in meaningless, I would love to see it. This is how I learn.

There is nothing wrong with lots of strands. They provide great flexibility with excellent high frequency response for AC applications such as audio & RF. They're not necessary for DC applications or even 60 Hz for house wiring. Highly stranded cable is harder to insulation strip without cutting some of the strands. I use a thermal insulation stripper. No matter. Besides, electrons flow from atom to atom & are not continuously independent. Solid flat thin wire is often used for high end esoteric audio applications for excellent frequency response & dynamic range. It's all about Eddy current flow on the conductor surface. I have a MSEE from Columbia University, class of "79 (no brag just fact). Call me at 408-802-0155 to discuss this if you like.

Regards,
Peter

P.S. Coaxial cable, which is used for RF, is a wave-guide with a single center conductor wrapped in a dielectric surrounded by a highly stranded shield. This is often covered by a metal foil & the cable can handle lots of current. Go figure. Give me a call.

P.S.S. The other thing too is that all the strands are touching each other. So what's the actual electrical/physical difference between solid & stranded wire other than flexibility? It's like the old Fleetwood Mac album (song): "It's a Mystery to Me" IIRC.

ok @windforfun , but to keep this thread on subject - can you see a reason that this particular product is going to be a poor replacement for the stock internal harness wire that I'm trying to replace? That's all I care about.
Laymen terms please, thanks.

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As a physicist, I do agree that the current runs on the surface of the strands, so more strands means more surface area and it tends to have lower resistance than a single strand in DC situations. It does not matter that the strands touch each other since on a microscopic level it is only the high points that touch. A bundle of many strands is physically larger than a single strand with the same amount of metal.

One important consideration in automotive wiring harnesses is the temperature rating. Most 914 harnesses would use the 125ºC rated wire as opposed to the common crap in the big box stores which is only rated at 85ºC. Also the sleeving used is not heat shrink tubing.

If anyone is parting out harnesses, I need a few of the big grommets where the harness exits the fuse panel area and enters the front trunk. I have also seen them on VW fuel injection harnesses. Part # 311 906 105 A molded into the part.

Whatever...

https://physics.stackexchange.com/questions...rface-of-a-wire

Scroll down to the middle.

Copper is soft & depending on the stranding & twisting processes there may be more or less strand surface contact.

Let's move this over to the garage.

This WTB thread is complete.

I'd like to continue this discussion but not in the classified section.

Mods could be watching

Rick

Yeah... So solid state physics can get a little complicated & weird. I don't think it's entirely understood even today. The physical processes typically use probability theory with regard to electron behavior in the atomic valance & conduction bands to model this stuff (quantum mechanics). It's been 40 plus years since I've studied this shit, but I think the jury might still be out as to what really goes on. Even Einstein didn't approve of some of these theories & tried to bring them into understanding with his unified field theorem. He failed. He wanted a deterministic model. His general & special theories of relativity have been proven to be true. There are numerous easy to understand books on the subject. IMO, it's fascinating & perhaps a definition or justification of God's existence. Just remember that gravity or near speed of light velocity changes or acceleration slow down time & result in distance contraction relative to an observer in a stationary frame of reference. The changes in time have nothing to do with the one's clock mechanism. Gravity bends light. Objects in space define gravity & gravity defines time. Blah blah blah...

Speaking of time, it's time for more wine. Cheers.



P.S. It's too bad pot smoking is so hard on the lungs. I guess you can theorize that I live in California.

#1 THANK YOU windforfun for the links. It gets deep pretty quickly but there is more to this than I have been taught before.
Engineers are ALWAYS good for information and opening one's horizons.

#2 In my first post I posted "Current thinking (pun intended)" and I was serious.
Electrical theory has changed enough over the years to make me think that it will probably change again and as I'm not at the forefront of electrical theory I will have to rely on others for my knowledge.
An EE should be a reliable source of knowledge regarding electronics, more so than a set of A&P instructors that were far more "shop dogs" than scientists.

I had a serious argument with one regarding running a manual gear box reverse rotation with helical cut gearing. He just couldn't get it through his head that the helical shape created thrust in the gear set exactly opposite to what it was designed for and where the thrust surfaces/bearings were placed.

Nobody has all of the answers...

Thanks again, windforfun.
You've made me think and I have learned something new.
I'm still going to use fine stranded cable when it's available but it's not as critical as I thought it was.

OT question. You a glider jock?
I got 3/4 of the way through glider training 44 years ago when I was 15. Caddo Mills (the glider airport) was nearly100 miles away from our house in Ft. Worth and my parents ran out of money for training, but I can fly a glider fairly well. High speed stalls are a HOOT in a Schweizer 233.

BTW you can forgo the lung problem with the contraband you are referring too.
They're called "edibles" and you should NOT allow your pet racoon to get into them.
https://www.youtube.com/watch?v=ANSh6NhVjRA

Since you guys have me ever so slightly concerned…
This replacement 8ga welding/battery cable is rated at 55w max amps… would it be prudent to add a 55 watt fuse up close to the battery? I think I remember such large automotive fuses used in the world of car audio? There’s none used with the stock set up and my replacement is a little thicker, but..maybe that would serv as piece of mind if nothing else.

BTW, just for a clearer reference, the fat red wire in this junction is the wire in question:

I'd fuse a wire rated for 55 amps with a 40 or MAYBE 50 fuse. I'd try to use a modern "Maxifuse" these are the big square ones with the clear tops. It's uncommon to see these in increments of 5 above 30 amps, so a 55 might be a PIA to find.

Car audio fuses for a big amp would work fine but will be many times more expensive than a maxi fuse and you probably can't get them at Auto-Zone on Sunday afternoon.

What are you powering with this circuit?
The first post said "up around the fuse box" but didn't say "all exterior lighting" or "secondary fuse box".

Tell me what you're feeding, and I'll have suggestions on how big to make the food bowl...

Dead giveaway that you have trouble in large gauge wiring is "how HOT does it get while in use"
If it's freaking hot you have screwed up somewhere...

Most of the time I'm choosing fuses by the draw I believe my power consumers are going to require. Rule of thumb for me is 1.5X my expected draw.
So, in my book, the proper fuse for a 20amp draw is 30 amps.

The fused item dictates the fuse I'm using, not the total ampacity of the feed wires themselves.

The exception to this rule would be a fuse box that I wanted the ability to add stuff to later. for your wiring I'd prefer a 40 over a 50.

@Windforfun comments. Do I have it right?

Yea a 40 or 50 watt fuse sounds more appropriate, makes since that it’s less than the actual wire and would burn up before the wire.. that’s the whole idea anyway.

This is the main wire that runs from the battery + to the pictured block ^ (which gets mounted to the chassis next to the original fuse panel under the dash on early cars).

I don’t have my schematic in front of me but I believe it’s mainly for the ignition switch and possibly accessories in general. Maybe its main function serves to power the fuse panel? I haven’t bothered to study that because it wasn’t necessary. my original intention was just to extend a cable that was already present (move battery to rear trunk). But then decided I’d prefer no splice.

I never intended to sweat the details of all this too much, but simply emulate what the factory did, with my longer replacement wire.

Im all for adding a little piece of mind tho, so if a fuse is recommended, let me know - I’d gladly add one.

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Adding an extra fuse in the circuit should be "transparent".

Aircraft wiring is often triple redundant and they could have multiple fuses in a circuit.

I'd rather have one too many than one too few when it comes to electrical safety devices.

Your modern car has a bunch of maxi-fuses BEFORE the fuse box. They take the place of "fusible links" that a bunch of older cars used.

Changing fusible links is a shitload more trouble than popping a new maxi-fuse in.

There are more styles of maxi-fuses than needed.
I'd choose the most common variant that can be found at your FLAPS or even Walmart.
Be nice to be able to get a fuse at 3am if you need too.

Finding a inline socket for it might be a bit more difficult...

Good morning everyone.

I would add up the current ratings of all the fuses in the panel. This sort of gives you the maximum current draw that you need to accommodate with a fuse at the battery. This assumes that all the circuits in the car are turned on at the same time.

This new fuse must be at the battery to protect the wiring (in case there's a short downstream). It must also be impervious to vibration & perhaps heat too. I would go with a fuse current rating of 1.25X the panel current sum. This is really just a best guess on my part.

The welding wire sounds perfect for this application. It should handle all the current the car can draw. Spade lugs should be crimped first & then soldered. Strands shouldn't be cut (for good workmanship). Shrink tubing is a nice addition too.

If this were a science project, I would recommend that you get your hands on a beefy ammeter & put it in series with your new wiring. Start the car, turn every thing on, hit the brake, & see how much current you are drawing. This is what the new fuse must accommodate without blowing. Chances are the welding wire won't give a shit & probably won't even get hot. I assume you'll be able to replace the new fuse with a larger one if necessary. A functioning alternator should be included in this test just for the hell of it.

I do my connectors the same way.

Spread wires apart a bit, dip in the soldering flux, twist the piss out of them and wipe excess flux off.
Install in crimp connection that fits tightly. Crimp with a pair of Thomas & Betts crimpers from the 60s. They intrusively punch the connector.
Add solder through the weep hole (in the connector) until I see silver wick up the wire into the insulation.
Cool instantly and clean off.
I use type 2 heat shrink, this is thicker and has an internal glue layer that melts when heat is applied.
I use a dedicated heat gun, a "Gar-tech" made in Germany. It's lasted 25 years already.
I've bent one of the attachments to completely surround the wire-heat shrink and it works perfectly.

After doing it that way you cannot see the splice/connector with a DVOM and I have destructively tested multiple gauges and connectors by attaching large weights, trying the wire off to something high, and dropping said weights.

The wire itself fails before the connectors do...

The solder joint should never corrode if you use the glue heat shrink and do it right.

Cool tool tip. I got a UNI-T UT210E DVOM. This puppy has an amperage clamp built into it. It's pretty small and this unit does DC amperage. Most amp gauges are AC only.
The UNI-T can do AC as well, but the clamp might be a bit on the small side for AC electrical work.
For DC work it's IDEAL!
I don't get a normal size DVOM out anymore. This is my go-to test equipment for automotive electrical work. It's inexpensive as well. About $55

https://www.amazon.com/UNI-T-Digital-Handhe...la-825340133445

Here's a relevant thread I found, on the subject of fusing battery wires. I'm now considering a small multi block of fuses in the rear trunk (with my battery) (see how these things evolve into more bullshit?)

http://www.914world.com/bbs2/index.php?showtopic=139890

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So it's down the rabbit hole we go. Thanks for the interesting correspondence. Keep the installation as simple as possible. Regarding the "science" of connectors, it looks very military/NASA grade. BTDT. And if you use tie wraps anywhere, make sure you flush cut the tails. If you don't you'll get cut.

Maybe 4 of these in parallel would work for our little science project.

My lungs will just have to get over it!