Scott:
I could not find anything in the UL white book that prohibits pre-twisting. I always used my long nose pliers, and lineman pliers and twisted the wires before using a
wirenut.
The use of tape at receptacle, or other device or equipment termination screws is just some additional insurance that one will not get a shock when replacing receptacles, because they forgot to turn off the power!
I was taught by my dad early on to use tape and I still use tape to protect myself!
