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Old 09-19-2008, 08:34 PM   #1 (permalink)
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Wire Splicing Basics

I've been putting wires together for a living since 1968 and hope this helps someone out there in 6.5 land
************************************************** *******
From JiFaire: Use rosin-core solder, good wire, and take your time ..... When you cut, be sure to offset a bit, so you don't have 6 splices side-by-side.

Jim & I have discussed this offline and I believe we're in agreement to the following:
IF you're going to solder the wires heed the above warning to use rosin-core solder! NEVER use acid-core solder, or flux, on anything electrical!!!
Also keep in mind that most solder is a combination of lead and tin, neither of which is a very good conductor of electricity. Make a good, mechanically sound, joint - The solder is just there to keep the joint from coming apart - Period. Heat the wire (not the solder) and flow the solder into the joint. Always obey the 3 Second Rule. If you have to keep the iron (or gun) on the joint for more than 3 seconds you don't have enough heat to do the job. This is very important because what's going on is the wire (in this case) is sucking the heat from the joint. Obviously this is heating up the wire beyond the joint. Common wire is soft drawn copper. When you heat it up enough it becomes hard - heat it enough and it becomes glass hard. A bit of vibration and it will break, usually right next to the joint. Getting a proper soldered joint actually takes practice and the correct iron or gun for the job.

That being said. You'll notice that all wire connections from the factory under the hood are crimped, not soldered... In fact, the major electrical trouble spots under the hood are soldered devices - The FSD and module for the wipers come to mind right off. In any area where heat and/or vibration are a concern crimped connections are the electrical industry standard.

So why do knowledgeable folks, like Jim, recommend soldering over crimping?
Here's the rub: You can goto WallyWorld, or places like that, and get a crimp connector kit. This is what most would do. This stuff is junk and will cause all kinds of problems later... Even though soldering a wire splice is almost always inferior to a crimped splice, using the wrong stuff negates any advantage that crimping gives the connection.
A good, permanent, crimp connection must be made with the right hardware and tool. The common stamped metal tool with the wire stripper built in is NOT the right tool. You can get a real crimping tool at almost any electrical supply house. I've also seen good crimp tools at Home Depot and Lowes. They are forged steel and actually designed for crimping (and occasionally cutting) wires. The forged tools keep the hammer and anvil alignment straight, while the stamped tool allows them to wander about a bit – This is not good.
Personally, I hate insulated crimp connectors. While there are some good ones out there, the type with the hard plastic insulation is very hard to get a good crimp with, and you can’t see the joint. If they are all that’s available I always remove the insulation. The other problem with them is that there is only one correct way to put the connector into the tool. You can’t see the seam with the solid color insulation. If you use quality, uninsulated connectors that are properly sized to the wire you’re splicing and crimp them correctly with the right tool you will always get a better, more stable splice than you can by soldering.
I always put a bit of NoAlOx on each wire before inserting it into the connector and then rub on some non-acidic silicone on the joint before putting some heat shrink over the joint. This gives you a corrosion proof connection. NoAlOx is a trade name for an anti-corrosion paste. There are several others, anyone of which will work. Home Depot, Lowes, and others carry similar products. They work on a molecular level, so just put on enough to coat the wire and rub it in. A big glob is counterproductive. I’ve made thousands and thousands of splices and terminations and am still using the same tube of the stuff that I bought in like 1980. The stuff should also be used on all of the terminals to ground. Again, just a light coating is all that is necessary or desired.

I should note that there are situations where a crimped joint will fail. Corrosion or big differences in the expansion of the metals used are two. Aluminum wire presents both of these problems. The other is tension. A spliced connection has to have some slack in it, or the wires will probably pull out eventually.

In closing – If you’ve decided that soldering is still the way to go for your situation, do yourself a favor and Google “Lineman Splice”. At least you’ll have an electrically and mechanically sound joint to work with.

Do it right and it will last. Do it haphazardly and it will come back to bite you – Probably when you least need a problem. This seems to apply to more than just electrical connections…

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Last edited by vstech; 07-25-2017 at 12:48 PM.
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Old 09-19-2008, 11:44 PM   #2 (permalink)
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Well done HamOp. Thanks for putting in that excellent information . I believe I learned a bit about soldering there and won't be as quick to add a dab. I agree that it is hard to beat a well crimped uninsulated connector with sealed heat shrink over it. quick and neat. If I do use a covered crimp connector, I will use the nylon coated. I just don't like the cheap pvc coatings.

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Old 09-20-2008, 12:16 AM   #3 (permalink)
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Nice post, HamOp... we've been talking about this one for a while now, and I agree with pretty much everything.

But I just gotta add me a disclaimer...

To the do-it-yourself-PMD-extension-harness-maker:

If you follow the directions above, you'll have yourself a great PMD extension harness!


If you want to crimp the connections, do it exactly the way you were just directed to.

If you plan on using cheap Wal-Mart crimpers, PVC connectors, etc, then Use resin-core solder and heat-shrink tubing instead. Simply put, a bad crimp job is worse than a bad solder-job.

That's the reason we have been recommending solder (instead of crimp) for years...

Thanks for the info, HamOp... this thread is going to the FAQs.
Mmmph. Mrmphhh!


Last edited by jifaire; 09-20-2008 at 12:18 AM.
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Old 09-20-2008, 12:33 AM   #4 (permalink)
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The only thing I would add is if you're going to use solder - get silver bearing solder - the higher the content of silver the better.

Also, a wire splice that is prepared properly and soldered properly AND sealed properly will provide years and years of trouble free wiring. I used to race electric R/C cars all over the southeast and every connection on my rides were soldered - some pulling in excess of 30 amps - never had one fail.

Very good article but I still cast my vote for soldering. If done properly it will have the same or less resistance than crimping. I seal all of my solder joints with silicone and shrink wrap....and they ALWAYS look better than crimping....and no corrosion.

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Last edited by odlaw; 09-20-2008 at 12:37 AM.
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Old 09-20-2008, 12:42 AM   #5 (permalink)
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Very nice tutorial HamOP.

I was in the conversion industry for years and we were in the big threes pools and governed by RVIA. One of the most stringent rules from them all was NO SOLDER. All fuse blocks and electrical connections had to be crimped and any electrical component that was purchased and had presoldered ends had to be cut and re-stripped. Nylon coated connectors were all that were approved to be used. They also required that the forged crimpers were used and even required Klein crimpers by name in some applications. I never really understood all the reasoning behind it but just that it was required. Now it is clear.
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Old 09-20-2008, 02:00 AM   #6 (permalink)
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Just when I got goot at soldering...

I had almost given up on criming stuff, mainly due to the pulling apart eventually part. Got pretty good at soldering, too bad the solder joint itself doesn't conduct electricity as well as we'd assume.

I usually twist the copper wires together, then solder, then trim the remains off, then insulate it well.
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Old 09-20-2008, 05:39 AM   #7 (permalink)
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What do you feel about these? Besides they are very expensive!
Are they worthless like crimping?
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Old 09-20-2008, 09:37 AM   #8 (permalink)
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DieselCash - Never even heard of those, so I have no idea... Try a couple if you can get your hands on some and let us know. Might be the splicers we've all been waiting for --- OTOH - The *old* stuff works and will continue to work - AND its cheap.
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Old 09-20-2008, 11:54 AM   #9 (permalink)
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HamOP, that was a good post, Experience thougt me to do it that way over the years,altough i do solder the joint after crimping ,and heatshrink is a godsend invention.
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Old 09-20-2008, 12:06 PM   #10 (permalink)
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Concerning Silver Bearing Solder & a bit of history

odlaw - No offense meant - Really!

Silver has the best conductivity of any metal, and that friends is a fact.
Back in *the good old days* electronic devices were wired point-to-point. Everything was joined at terminal strips, where a solid electrical connection could be made and solder added to secure the joint. Then in the '70s printed circuit boards (pcbs) became the norm.
On a pcb the device wires are put through a hole in the board and soldered, there is no solid electrical connection. There was a lot of debate at the time in industry about the viability of pcbs because the solder was actually being used as a conductor, and solder is not a good conductor of electricity. Silver was introduced to the solder just to overcome this problem. Which created yet another problem.
The new problem was that silver bearing solder takes a lot more heat to get a good joint and the traces would lift from the boards - This is BAD! New pcb materials were then developed to solve that problem and all was right with the electronics world.
BUT - We're discussing splicing wires, not soldering pcbs. The added heat is a killer of soft drawn copper wire - It gets really, really hard at the joint. For this reason silver bearing solder is not recommended for splices. In fact solder is just not recommended for splicing soft drawn copper wire, which is what we're working with. It's even worse when using stranded wire!
A correctly soldered splice (remember, we're talking splicing) is done with solid copper wire that has been solidly electrically and mechanically joined. The solder's only purpose is to keep the joint from unraveling. So, in our case, the silver bearing solder simply isn't justified on any level. Too much heat is needed and conductivity is not, nor should ever be (in a splice), an issue.
As JiFaire pointed out - You really are better off soldering than using the wrong material or tools for a crimped joint. But using the correct material and tool will always give you a more stable splice than soldering. And that's what you want - A do it and forget it splice.

One other thing. While in grade school I got a Heath Kit (radio, not FSD ) for Christmas. Soldered it together - plugged it in - blew the house fuses. My dad worked with a ham and took it to him to check out. Turned out that it was my soldering (to use the term loosly) that was the problem. That old ham op (ham radio operator) graciously taught me how to solder, and later I taught soldering to electronic repair apprenticeship classes in the '60s and '70s. I still love to solder and strive for perfect joints. 50 years later I'm still building radio kits and radios from scratch. Almost nothing makes me as happy as turning on my own design and having it actually work .

Bottom line: There are situations where solder is called for and those where it is not. Splicing soft drawn copper wire is one of the latter.

THE whole point is making an electrically and mechanically stable joint.

Last edited by HamOP; 09-20-2008 at 12:09 PM.
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