According to bud-- :

Twisting the wires, with no solder or "splicing device identifified for
the use" [wirenut], is a code violation and is *insane*.

No kidding. Sheesh!

A couple of thermal cycles later, you will almost certainly
have an intermittent, arcs, and possibly a fire.

The wire _must_ be positively connected, whether by wirenut,
solder or proper crimp device. Electrician's tape is an insulator,
not a crimp device.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.