My father, who is a semi Retired Electrician/Engineer, and myself got into this debate. He then sent me a link to this thread and after reading most of the posts I notice that the sword still swings both ways on this issue. Now here is my knowledge.
First, Proper wire nut termination. If I have solid wires That I am terminating, I twist them together. No-Brainer there. If I have to a any stranded to the mix I twist the stranded, position it slightly higher (1/8-inch) then the solid group and push them in to the wire nut and twist. This will have the stranded go into the thread, and then solid group push the stranded up and against the threads. I get a very solid connection when I do this and I know cause I aways check with a smart tug as anyone should always do when they terminate a connector.
Now my Dad does it different by twisting the solids and stranded together. That's how he originally taught me but every-time I do it the stranded snakes it way out of the bundle before I can get it nutted. He says it's because he's just that good.
To tape or not to tape?!
My company has a policy that taping is only necessary when termination the motor. Over time heavy vibration from these motors that are turning pumps can potentially cause the wire nuts to back off. This has not in my experience happened yet but we don't take that chance. Nor do we plan on wanting to find out. Having one of those connections come loose will be very costly to our customer and to my company that it is part of our procedure to tape them.I have even been told by a contract electrician that it is in violation of the NEC not to. Whenever someone Says something is Code or Not Code I always look it up. I haven't any mention of it in the NEC or the NFPA 79. However, for us and myself taping the wire nuts on motor connection is the safety net. You may never need and you don't want to find out. But, it's comforting that it's there just in case. To say that "If it's put on properly it won't come loose" is a boisterous and risky move.
To add to the other comments I have seen about the stick hassle of taking the tape of, I apply the tape in a manner so that it can be removed easily for service. because I have also have to mess with that mess too many times.
What I do Scotch Electric Tape. It seems to come off a little cleaner then other brands like 3M.
I start about 2 inches down the wire and wrap up to the wire nut at the end of the wrap, I fold the end of the tape so the next guy taking it apart has something to grab hold of.
In my opinion, motors terminations are the only terminations that get taped. and its for for the precautions against vibration only. If anyone tapes for moisture they should be using appropriate JB or Enclosure for those conditions.
And if people are going to look for sources for good wiring practices, you can't go wrong with the NEC. Or your on good common sense.
Many instruction manuals are like the one posted for what looks like a home light fixture written for Joe Q. Public in a manner that nothing can go wrong. The manufacture does not want any lawsuits because something wasn't in the manual and Joe's house burnt down or he got YARKED.
The only other times I ever use electric tape is for temporary use. Until I make a more permanent and professional connection. And for wrapping split bolt connections.