Wire stripper and twister - GIF

[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