In article .com,
writes:
Clearly impractical in many cases. Soldering is good, but proper
mechanical support of the joint is essential, as solder is very weak.
The effective way to give this support is to twist the 2 copper wires
together for many turns. The far ends will not move relative to each
other. But insulation?

I do solder them. One way is to use a regular junction box
in the normal way, and then solder up the connections too.
However, this type of soldering is a skill most electricians
won't have, so I don't recommend it unless you are very
proficient at electrical soldering already.

If starting from a no skill base, teaching someone to make
reliable crimp connections using a proper ratchet crimp tool
is going to be much faster than teaching them to make reliable
solder connections. As bob has found, some people can't even
get this right (a properly made crimp won't fail in this way).

I await the day when we spot weld all joints.

Spot welding is a very skilled job, and not an accepted way
to make such connections. Brasing is the third permitted way,
but usually not practical.

--
Andrew Gabriel