Red Wire from Early Wiring Harness, (formerly WTB ad) Options

[Literati914]

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.

.

[davep]

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.

[windforfun]

Whatever...

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

Scroll down to the middle.

(IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif)

[windforfun]

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.

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

(IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif)

[technicalninja]

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 (IMG:style_emoticons/default/beerchug.gif)

Rick

[windforfun]

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.

(IMG:style_emoticons/default/smoke.gif) (IMG:style_emoticons/default/smoke.gif) (IMG:style_emoticons/default/smoke.gif)

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

[technicalninja]

#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

[Literati914]

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:

[technicalninja]

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...

[technicalninja]

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?

[Literati914]

I'd fuse a wire rated for 55 amps with a 40 or MAYBE 50 fuse..

..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".

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.

.

[technicalninja]

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...

[windforfun]

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.

(IMG:style_emoticons/default/flag.gif) (IMG:style_emoticons/default/flag.gif) (IMG:style_emoticons/default/flag.gif)

[technicalninja]

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

[Literati914]

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?) (IMG:style_emoticons/default/headbang.gif)

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

.

[windforfun]

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.

(IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif)

[windforfun]

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

(IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif)

[barkamatic]

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.

(IMG:style_emoticons/default/smoke.gif) (IMG:style_emoticons/default/smoke.gif) (IMG:style_emoticons/default/smoke.gif)

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

My lungs will just have to get over it!