Soldering wires went out in the 50's. It's no longer approved. For those who missed the experience, after the wires were soldered and while it was still hot, rubber tape was wrapped around the splice first, followed by friction tape (tar soaked cloth tape). And yes, it was quite a chore undoing such a splice, but it surely guaranteed a good connection

Lead solder was never a good conductor and created problems for high current applications, (power grid connections, protection grounding clamps) . High current through a poor conductor material created the possibility of vapourising the solder and blowing the connection apart.  High compression connector manufacturers claim a hermetic seal between metals.

 

Thermite welds are used for some connections and bonds the metal pretty well.

Our local code inspector requires wire nuts to be electrical taped. Not sure why.

 

 

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Our local code inspector requires wire nuts to be electrical taped. Not sure why.

 

There's nothing in the code that prohibits that. I've taped some wire nutted connections on occasion when the wire nut didn't completely cover a bit of bare wire.