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Small Cabin Forum / General Forum / OT: Best way to connect 2 wires
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Smawgunner
Member
# Posted: 9 May 2017 20:08
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I'm installing two new tail lights on my trailer. I think it's 12 gauge wire. What is the best way to connect two wires? I always have used those pieces are you stick a wire in and crimp it down and wrapped with electrical tape. Should I solder it instead? Just not sure if this was the best method for stranded wire.

ICC
Member
# Posted: 9 May 2017 20:32
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Those "add on" crimp connections work okay, I have used them many times and can't recall a failure. I like to use the stretchy silcone tape to seal out moisture as that stuff self vulcanizes after it is wrapped tightly.



OTOH, if you can make a good solder joint, use flux made for electrical work and seal it well... again I like the silicone type best. Too many people can't solder correctly and end up making soldered connections that can pull apart.

DaveBell
Moderator
# Posted: 9 May 2017 22:45 - Edited by: DaveBell
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Strip back 3/4" insulation. Cut 1" piece of shrink wrap tubing. Put the shrink wrap on one wire at least 2" back. Face the two wires at each other, overlap the bare wire by 1/2". Hold one side twist the other. Hold the twisted side and twist the second side opposite direction. Solder wires together. Solder should "flow" to both sides so you don't get a cold solder joint. Move shrink wrap, center over bare wires ensuring the wrap will shrink onto the insulation on both sides. Shrink with butane lighter, not letting the flame touch the wrap. I do one side back and forth, then after that side has contracted, turn the wire and do the other side. Slower is better. Too much heat and the wrap will split and burn. The proper way is with a heat gun but a butane lighter will work with practice.

This provides a strong mechanical, electrical and insulated connection.

Shrink wrap tubing shrinks about 50% but has to be large enough to slide over the twisted pair and the insulation on each side.

ForceFed70
Member
# Posted: 10 May 2017 02:30
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I do it like Dave. That's the way they taught me to do it in school.

Aircraft mechanics will tell you that the best option is a quality crimp connector with proper crimp tool. The argument is that a crimp connector is better suited for areas that see lots of vibration like a vehicle/trailer.

toyota_mdt_tech
Member
# Posted: 10 May 2017 08:54
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In a trailer were weather is an issue, I would twist together, solder and shrink tube. Home Depot has nice water tight shrink tube. Just make sure wire is secure, movement ie wind will break a solder joint. They make those but splices you mentioned with shrink tube built on it, this is the second best option.

paulz
Member
# Posted: 10 May 2017 09:19
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Another option for sealing the connection is liquid electrical tape, a thick paint on flexible coating. Easier to apply in confined spaces where heat or rolled tape are difficult.

Cowracer
Member
# Posted: 10 May 2017 09:44 - Edited by: Cowracer
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Soldered Western Union splice. While it was designed for solid wire, I find it works well on stranded too.

URL

When you solder, use the iron to heat the wires, not the solder. A small dab of solder on the iron helps transfer heat, but other than that, you should never apply the solder directly to the iron.

When the wires are hot enough to melt the solder, it will suck up in all the little crevices and give you a good joint. If you us the iron to heat the solder, the solder will just sit on top of the cold wires and give you a poor joint.

Practice a few times and you will get the hang of it.


Tim

P.S. I would be shocked if your trailer lights are 12awg. Probably more like 16 or 18.

NorthRick
Member
# Posted: 10 May 2017 16:05
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I like to add some silicon under the heat shrink tubing. Slather it over the wires after you crimp/solder them, then slide the heat shrink over and heat. As the tubing shrinks it should squeeze excess silicon out. Wipe it off and you have a good water tight connection.

toyota_mdt_tech
Member
# Posted: 10 May 2017 17:21
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Quoting: Cowracer
P.S. I would be shocked if your trailer lights are 12awg. Probably more like 16 or 18



He may be seeing electric brake wires, is what I was thinking. Or the aux charge circuit etc.

sparky30_06
Member
# Posted: 11 May 2017 07:48
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do not solder wires on a trailer. this will create a solid joint to a stranded joint and the vibration will cause it to break. best bet is good quality butt splices that have heat shrink built into them and a good quality set of crimpers. Then if you want added protection add additional heat shrink over that.

Western Union splice brings back old memories for sure!!!

DaveBell
Moderator
# Posted: 11 May 2017 08:51
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In the North, salted winter roads, soldered connections are the norm due to the fact that salt eats the aluminum crimps in about 2 seasons. Heat shrink will not seal out salt. So crimp away. My solder connections have lasted over 12 years on my old trailer. My wiring is supported with ty-wraps. I guess if you let the wiring flop around, it might fail.

sparky30_06
Member
# Posted: 11 May 2017 14:55
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I grew up in north central Illinois and outside of Chicago. They dump more salt there than snow falls so I know all about salt corrosion. If you use high quality heat shrink butt splices you will not get any penetration. Now go buy the cheap ones from harbor freight and use the incorrect crimper and puncture the protective jacket then yes they will fail. Ever worked in a salt water environment?? That's even worse than the salter winter roads in the north county

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