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Joining mis-matched wires


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Hi all,

 

What is the proper way to join wires that require different crimp connectors? For example, I bought LED lights that come with tiny wires (I won't even hazard a gauge....SMALL!). The leads feeding them are not large, but are several times larger. I can't crimp them together, so what do I do?

 

Also, I have another situation where I have 3 x 18 AWG wires brought together, and I need to join this to another very small wire.

 

Can I use some sort of mechanical connectors? I can't use a bar because the wires need to tuck up under a light fixture.

 

Thanks for any help.

 

J

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some options

 

- fold the little wire a few times to get it in the crimp

 

- slide the plastic cover off the crimp, crimp the wires, then solder them before sliding crimp back on

 

- forget the crimp, slide on some heat shrink, twist wires together, solder, slide over heat shrink, shrink

 

- use chocolate block connector strip

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If it were me, I wouldn't use crimp connectors at all, borrow or buy a Butane soldering iron, and solder the wires (end on end). The existing wires will need to be cut back and clean for the solder to run properly. Use heat-shrink of an appropriate size over each wire, pulled back far enough to not get shrunk during soldering. Then when done use self amalgamating tape to wrap the joint. If done well it will be neat/waterproof and last for years.

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Actually, best practice is to use crimped connectors, but the brand of the quality ratchet crimper must match the terminals being used. Next best, IMO is to solder and cover the joint with resin cored heat shrink...

In this case a soldere, heat shrinked joint will be fine, provided the wires are properly supported.

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Ha, this is another subject with often Polarised views on Crimp or Solder. Some even argue about twist and not twist the wires. Well I spent a great deal of my life in the Industry of Commercial Audio/Video installation and even some Avionics where I was going to be teaching the subject.

An old Broadcasting Industry Guy said to be once, you have to think like the wire. Yep he was one of those Broadcasting geeks and I kind of "internally rolled my eyes" at his comments. But years later I started to understand what he was on about and now use the comment when installing. Hmmm, I guess that means I have been Geekafied.

The important point to understand re the solder not to solder argument, is that this is determined by the type of connector/terminal used. Not the wire, not the application nor the " which is better" arguments. A crimp terminal is designed to be crimped and a solder terminal is designed to be soldered. If you solder, you must support the wire. A soldered connection will not take vibration and movement of wire to joint. Heatshrink over the terminal and solder joint and back on to the wire to support the joint and then the wire needs to be tied to stop any possible movement. A crimp will actually handle a fair amount of movement.

The first biggy and most difficult issue is the Crimp and the crimping tool. There are cheap and there are expensive. Like everything, the expensive is so for a reason. But a good crimp tool can be super expensive and completely outweighs the job when you only have a few connections to make. And the real cheap tools are often so bad, it's a difficult call as to whether crimping is even worth it. So if you can and if you are making just a few crimps every now and then, try and get a reasonable middle of the range tool. Look for one that does NOT have that simple point that pokes a single dimple into the connector. Look for one that encompases the crimp and creates a longer crunch down, preferable the length of the crimp.

The second is the crimps themselves. Get thee to Jaycar and look for the crimps that have the heatshrink jacket on them. A little more expensive than the standard crimps, but on a Boat you simply will never regret using them. Well you might if you just realised you made a mistake and have to cut all you hard work and expensive little crimp off again so yoiu can feed a wire through a hole you just forgot to feed it through.....but hey, that never happens to me of course :shh:

Using these little wires is a complete pain in the neck for the poor installer. Manufactures using these little fine wires are not helping anyone. The best practice for dissimilar wires is that you should have a connector to suit each of the two wire sizes and a joiner to take both. That is not always practical in a small simple installation and so we are left with silly incorrect ways of joining wires.

The best practice is to get the little crimp that has a pin on the end. It is designed to be inserted into a Chocolate block strip connector and the screw clamps down on the pin. While we are at it, even strip connectors can have cheap and expensive forms. If you can find, try and get a strip connector that has a flat the screw clamps against the wire. This spreads the load and connection over a greater area of wire and stops the screw chopping into fine wire.

The last point is a difficult one. Don't over tighten the screw of a strip connector. Firm but not too tight. Most especially if you don't have a crimp and are screwing the connection onto a bare wire. If you are screwing to a bare wire, then you fold the wire tip in half and the screw comes against the folded over piece, so as the screw bites into that and not the main conductor. NEVER EVER solder the wire before connecting into a screw type fitting like a strip connector. The Solder stops the wire from giving a "springy" effect, so that has movement occurs like heating cooling and vibration, the screw will lose connection to the wire and the joint becomes lose. It's a pain in the neck. No matter how tight you make the connection, the darn thing comes lose again. Sometimes wires come pre soldered.ed to find this often on Car radios. Just cut the soldered tip off and used the bare wire.

And finally, if you want to ensure the joint is corrosion proof, you can use a little electrical grease in the joint, or you can coat the finish crimp with liquid tape. A little expensive, but well worth the effort.

Anything I missed??

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