Shok, that is asking for an electrical fire. I have been doing electrical for over 40 years and have seen a lot of fires caused by that kind of splice. If one has a properly adjusted irreversible ratcheting type crimper with the die that matches the crimp, reliable crimp splices can be made. Get a contact style soldering iron. They run on battery, cost less than $20, have no cord, and won't burn you if you grab the wrong end or put our arm on it when working under a dash.
If I'm going to connect two wires together without a crimp, I use a Western Union splice. I start by sliding heat shrink tubing over one wire that is 1.5 inches longer then the splice will end up becoming. This is because heat shrink tubing will also shrink lengthwise and I want a good overlap at each end. Then I'll twist the wires together like so: Next I'll apply iron heat from above and apply solder from below until the solder is drawn up through -- making sure not to melt the insulation. Allowed to cool, then center the heat shrink tubing over the splice and finally gently heat the tubing until shrunk.
Yeah, unless you apply solder, even doing a WU splice is asking for trouble. A twist splice is only for AC circuits and must be capped by a proper-sized wire nut.
When I do a splice on multi-strand wire, I separate the strands on both ends then push them together and gently twist, then solder together. I prefer liquid flux for these for the fact it wicks through the strands.
The wirenut has a tapered screw internal that when properly applied maintains compressive force on the splice. They are optimal for conditions where the wire is stiff and there is little or no movement. Finely stranded pliable wires, like welding and automotive cables, do not make good lasting connections with a wirenut. In motor control centers, where fine stranded wire is utilized, you will never see a wirenut unless it was installed by the janitor or the foreman.
I don't want to contribute to a total derailing I ft this thread, but if you have a quick explanation you can steer me to that would explain the fire hazard I'd appreciate it. Always willing to learn. Note that my preferred method is soldering, I just don't like generic crimps and have no experience with fancier crimps.
Shok you contradict you self here. what John is referring too is just twisting the wire together, on a higher amp circuit a straight twist connection can lead to a loose connection that can build up enough heat to start a fire. Speaker connections are low enough amps that they will not cause a fire so you could get by with just twisting those not good for sound quality but probably poses no fire risk. Now if you did that to you heater blower motor, one of you headlamps, or you alternator charge wire you could actually build enough heat to melt the insulation and cause a fire.
Well to clarify when connecting wires I prefer soldering above all, if I can't do that and I have to choose between crimp butt connectors (usual kind you find at flaps) or twist and shrink, I go twist and shrink. Good to point out the type of circuit, I was thinking more radio/gauges. Even tho I probably did do it was something high draw like fog lamps back when I was a kid and had my first car