PDA

View Full Version : A few words about wiring.....



12-26-2007, 04:30 PM
Over the years, I have had some pretty bad experiences with trying to wire up accessories such as fog lights or electric fans. I remember buying from a big box automotive store a "universal fog light wiring harness" that was so poorly built with inferior wires, switches and relays that I almost torched my car. The wires to the lights got so hot that they burned through my harness bundle over which they laid. Then the whole aftermarket fog light harness went up in flames, literally. Had a similar experience with an aftermarket fan and the harness that was sold to go along with it. Enough! I finally got out Dan Masters' book on electricals and custom wired my Cibie fogs with superior-quality wires, connectors and relays and have had zero problems since. The electric fan route took down a similar path. Finally ended up with a Spal fan and Spal's super quality wiring harness for their fan. <<www.spalusa.com>

So, if you are attempting to add accessories, do it right and buy the good stuff. I went to a marine electrical supplier for all my wire and relays for the fogs and used Spal's stuff for the fan. And everything is connected with British Wiring bullet connectors!

Just my 2 cents.

Bugeye58
12-26-2007, 04:33 PM
Good advice, Bill. There is a lot of absolute crap being marketed, and it pays to go with the quality stuff. I've always gone slightly overkill on wiring, for that very reason.
Jeff

Tinster
12-26-2007, 05:03 PM
Bill ! /bcforum/images/%%GRAEMLIN_URL%%/iagree.gif

I purchased a set of "emergency" driving lights when I was
installing Dan Masters Power Block entire car wire harness.

Being a rookie, I would have installed those cheapa$$ wires
had I not been holding Dan's wires in my hands.

Now I keep a small supply of British Wiring bullet
connectors and premium grade wire for odds and ends.

d

2wrench
12-27-2007, 12:23 AM
Wiring is just another issue that I am hoping to deal
with at a later time and try to get by with what I've
got. I'd like to do some upgrades that will probably
require more juice.

DrEntropy
12-27-2007, 02:06 PM
I'm one of the "solder the connectors" camp, others are firmly for the crimp connectors... bottom line is: get the good wiring and connectors, the proper tools and learn the proper techniques. I have NEVER had electrical troubles with ANY of my personal LBC's. Customers' cars are another story. Poor crimp connections, "Scotch-Lok" THINGIES, SPEAKER wire for lighting applications... a LONG list of up-screwed botches which can lead to lessons in how to make an LBC "bark" (think: "WOOF!").

TR3driver
12-27-2007, 02:22 PM
I'm one of the "solder the connectors" camp, others are firmly for the crimp connectors...While I've got a foot in each camp ... IMO solder + crimp is best. The crimp provides strain (and vibration) relief for the solder joint that provides the actual electrical connection.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I have NEVER had electrical troubles with ANY of my personal LBC's.[/QUOTE]Well, I certainly can't say that. But I can say that I've learned my personal "best practices" the hard way; by finding out exactly what the shortcomings were of other methods. Little things like not using a lockwasher in a ground connection can come back to bite you when you drive the same LBC almost every day for almost 20 years.

DrEntropy
12-27-2007, 02:31 PM
Me Ol' Fella was an EE type, so I learned from the best. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif


I can't say the same thing about the Italian cars, BTW.

Plastic LBC's are a particular challenge, too. Every electrical widget gets a ground wire!

TR6oldtimer
12-27-2007, 03:29 PM
The proper wire size to use in any application is determined by voltage, amperage, and distance.

Here is a neat set of charts that details the appropriate wire size to use in many applications.

https://www.windsun.com/Hardware/Wire_Table.htm

12-27-2007, 05:29 PM
I notice in that chart that there is not even mention of 16 gauge and above wire for 12v electricals. Hmmmmm. I remember that silly-arse driving light harness had what seemed to be 20 gauge wire!

Actually, wiring, even though I know very little about it, can and should be a very relaxing adventure. With a good book like Masters', one can just toot along, do a neat and logical job and end up with a professional result. What is scary is to look under some people's dash and see a bird's nest of two colors of wire and lots of electrical tape hanging down. That is when you need a new professionally built harness. British wiring does a good job.

When my buddy custom-rewired his TR8 with helicopter wires, it looks like a nuclear power plant inside: everything runs in an orderly and neat manner. Kinda cool to look at.

PeterK
12-27-2007, 05:42 PM
I've always thought that when you solder a connector, it makes the wire more brittle and both the wire and the bullet/terminal more susceptible to breaking from vibration.

If both sides of the wire are secured from vibbbration, then it's OK to solder. Otherwise, crimp is a better choice.

As Randall stated, I also use a "dab" of solder on the wire in addition to the crimp to insure full contact of the wire strands to the terminal. I also heat-shrink-tube every new connection I add.

DrEntropy
12-27-2007, 06:06 PM
Well, as I said: two camps. Soldering the wire into a bullet connector or ANY connector doesn't make it more prone to failure IMO. A copper multistrand wire is VERY difficult to work-harden to the point of embrittlement and subsequent fracture. Adding solder does nothing to hasten embrittlement. The usual failure comes from a "cold" joint where the solder may fracture away from the connector. Proper technique prevents that. I see it as a situation where a mechanical contact between two dissimilar metals alone (copper and the connector) will eventually corrode or succumb to electrolysis at the contact point(s). Solder is a good chemical interface for preventing it. Vibration of a frequency/duration to break that joint would be less a concern in an LBC than an aircraft. And longevity would be greater than a strictly mechanical joint.

That's my story and I'm stickin' to it.

TR3driver
12-27-2007, 06:17 PM
I notice in that chart that there is not even mention of 16 gauge and above wire for 12v electricals. Hmmmmm.Means basically nothing, except they chose not to include it. A lot less likely to be used in a photovoltaic system than in a car, perhaps.

I only spot-checked one number; but there seems to be a problem. The chart claims that using 206 ft (round-trip) of 10 AWG at 12v 2 amps; "5% of the power would be lost to resistance". Well, 10 AWG copper (assuming they mean solid, which they don't specify) is very close to .001 ohm per foot (.0009989 @ 20C), so 206 ft would be 0.206 ohms, which would dissipate only 0.824 watts at 2 amps. But, 2 amps @ 12v is 24 watts, and 5% of 24 is 1.2 watts. Doesn't add up.

So, I thought perhaps they meant the total drop in power because the current would be less (assuming the load resistance stays the same, which it rarely does in the automotive world). But if we work it that way, 12v @ 2A means a 6 ohm load; and if we add in the .206 ohms for the wire, we get 12v across 6.206 ohms or 1.9336 amps; which divides as 22.43 watts into the load or a drop of 6.5%.

There's also the question of whether 5% power "lost" is the appropriate number for automotive wiring or not. Kind of depends on the circumstances, IMO. Going back to the 206 ft of 10 AWG; their number would give a drop of .42 volts. According to Daniel Stern, that's enough to reduce headlight output by 10%, which IMO would be unacceptable.

TR6oldtimer
12-27-2007, 06:32 PM
...Going back to the 206 ft of 10 AWG; their number would give a drop of .42 volts. According to Daniel Stern, that's enough to reduce headlight output by 10%, which IMO would be unacceptable.

206 feet? Must be a very long car. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

TR6oldtimer
12-27-2007, 06:39 PM
On the soldering vs crimp. I once had a 35' wooden boat that was moored in Long Beach Harbor, a very moist environment. I soldered all electrical connectors, not for mechanical connection, but for corrosion protection. The connection was then covered with shrink tube to better seal the cit and provide mechanical support. Probably an over kill, unless you live in Puerto Rico, where everything seems prone to rusting.

TR3driver
12-27-2007, 06:54 PM
But copper will corrode just exposed to ordinary air ... fresh copper is a very light golden color while that reddish brownish shade you're used to seeing is actually a coat of copper oxide, which is a lousy conductor (actually used as a semiconductor before better minerals were found).
https://encyclopedia.thefreedictionary.com/Copper%20(I)%20oxide

I don't think it's overkill at all.

TR3driver
12-27-2007, 07:00 PM
I've always thought that when you solder a connector, it makes the wire more brittle and both the wire and the bullet/terminal more susceptible to breaking from vibration. I agree. Within the solder, the wire acts like solid wire, making it much stiffer than stranded (which is part of why we use stranded wire in the first place). Then at the boundary of the solder, the sudden transition provides a single point of stress, making the wire more apt to flex at only that point. Any stress is also amplified, by being applied to only a few strands right at the transition. Kind of like the old trick of how to rip a phone book in half.
https://www.ripaphonebook.com/

TR3driver
12-27-2007, 07:10 PM
Me Ol' Fella was an EE type, so I learned from the best. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif Well, I studied EE at Purdue ... but eventually decided computers were more interesting. Besides, those guys never get to actually build anything and I like building things.

My freshman year, I was in the HKN (EE honors society) lab (where I shouldn't have been), modifying an audio amplifier from a TV station to use as a guitar amplifier. Some senior wandered in to run me out, but stopped to watch what I was doing ... he eventually remarked that he was about to graduate with honors but hadn't the faintest idea how to do what I was doing ... just winging it without benefit of a Bode plot or gain transfer diagram; plus actually soldering the wires together and making it work. After that, I had the run of the lab. Oh, and the amp worked great.

2wrench
12-27-2007, 07:11 PM
No twisty black tapie camp, eh?

DrEntropy
12-27-2007, 07:27 PM
I'd do a boat the same way, Ray. Wood or 'glas.

Randall, If said transition has solder extending thru the wire, outside the body of the connector it is poorly soldered.

We could argue th' toss here for DAYS. All I know is; I've never suffered a problem from my soldered connectors (talkin' the better part of forty years in some cases), but more than a few mechanical joints have given me grief. NOT the staked connections from manufacturers' copper on copper alloy connector using an arc & stamping, rather the in-the-field "repair" ones.

I'm an ol' dog, I'll likely keep a grip on my solderin' pencil as long as I can. /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

TR3driver
12-27-2007, 07:48 PM
Randall, If said transition has solder extending thru the wire, outside the body of the connector it is poorly soldered. And if the body of the connector grips the wire so tightly it cannot flex inside, then it's crimped.

I have seen soldered wires break; tho I'll agree never a connection using a terminal that I made myself (since I don't make them that way). Used to work onboard seismic survey ships, where they set off the equivalent of a keg of dynamite under the stern every few seconds for days on end ... I don't think there is any kind of connection I didn't see fail at least once.

But that's the nice things about opinions ... we're neither one wrong, we just have different opinions. Wouldn't the world be boring place if we all agreed on everything ?

DrEntropy
12-27-2007, 09:08 PM
I have the opinion we'd be within 0.005" tolerance of one-another! It's all in the execution of the J-O-B.

Floatin' around on a seismoligist's wet dream would be a bit outside my particular 'tolerances' tho... hat's off to ya.

Bugeye58
12-27-2007, 09:17 PM
When I do bullet connectors, I use the solid brass ones, and, after applying the proper hexagonal crimp, wick in solder through the hole in the end. The solder insures a good connection, while the crimp provides strain relief.
Delco/Packard Electric require soldering of connectors for field repairs, rather than just a crimp. Even using the proper ratchet style crimpers on my Weatherpack terminals, I still solder them. However, the Weatherpacks have built in strain relief, so I think it's a non-issue in this case.
I've never had a connector failure yet.
I think the ability to <u>properly</u> do a solder joint may have some bearing here. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Jeff

rlandrum
12-28-2007, 01:58 AM
I found this to be useful...

https://www.powerstream.com/Wire_Size.htm

From what I can tell, just about everything is 16 gauge in the car, which is more than sufficient unless you wanna run hundred watt brake lights, and even then it'd probably still come in under the 22 amp rating.

As for the 20 gauge fog lights, that wiring is probably too small, especially if they were the 80 watt variety. Even the cheap 55 watt ones would be close to the max.

PeterK
12-28-2007, 08:05 AM
From what I can tell, just about everything is 16 gauge in the car,...

Maybe this link will help
https://www.britishwiring.com/CAT02_07.PDF

TR3driver
12-28-2007, 01:46 PM
From what I can tell, just about everything is 16 gauge in the car,I don't recall the AWG equivalents offhand (oddly enough the British don't use American wire standards); but there should be at least 3 different sizes of wire in a TR3 harness. The brown wires (with various tracers) between the starter solenoid, control box, fuse block, horns, ammeter, ignition switch & main headlight switch are heavier gauge than the rest of the harness; while the wires to the dash illumination lamps are smaller. ISTR the turn signal wires through the stator tube are smaller as well.

The cheap fog light kit I bought had 20 AWG wire in it ... but only for the control circuit for the relay. The power wires were heavier, like maybe 14 AWG.

Bugeye58
12-28-2007, 02:07 PM
Here's a link to the B/W catalog page that translates the wire size in relation to its current carrying ability.
Jeff

https://www.britishwiring.com/CAT02_07.PDF