Wire stripper and twister - GIF

[Frank S]

Hmm, nothwithstanding the quality of the cable twist created by that tool, soldered connections are, AIUI, not acceptable here in UK. Crimped or WAGO joints and similar maintenance-free connectors are preferable.

yeah the only time you will find soldered connections here either is in low voltage applications I've seen some silver brazed connections in 4300v panels and in 600v DC always backed up with another means of securement.
Some photos of acceptable connectors in various parts of the world
almost the only type of connector used in house wiring in the middle east

very popular in the USA

My preferred after a connection is tightly twisted, if the wire is stranded I like to solder as well then these are crimped over the connection

[VinnieL]

I was told the reason the U.S. Electrical Code prohibits soldered connections is that too many people think "soldering" is laying two wires side by side and running or globbing molten solder between them. The lead, silver, tin of the solder melts wasily and can result in an open or short circuit or fire.
It does take a good mecanical connection to make a good electrical connection.
I like this tool!
Some people simply stick the stripped ends of wires to be joined in a "wirenut" and twist the wirenut. I never did trust that type of connection and always tightly twist them before inserting in the nut, otherwise you are expecting that little steel spring inside to conduct the current of the joint.

[Frank S]

too many people think "soldering" is laying two wires side by side and running or globbing molten solder between them. The lead, silver, tin of the solder melts wasily and can result in an open or short circuit or fire.
It does take a good mecanical connection to make a good electrical connection.
Some people simply stick the stripped ends of wires to be joined in a "wirenut" and twist the wirenut. always tightly twist them before inserting in the nut, otherwise you are expecting that little steel spring inside to conduct the current of the joint.

Exactly; I've had to repair countless wiring harnesses in vehicles where the manufacture had hidden splices and branch off connections deep in the harness which were merely soldered together without and form of other securement to hold the ends together.
Not all wire nuts are created equal many don't even have the conical shaped steel spring in them, just plastic threads which may or may not be OK I only know that I don't like them and don't trust them even when having the ends firmly twisted prior to their use