I have been told that it can be but I. I think my friend is trying to scare me. I don't see the difference in the tape. grrrr
It's a bad idea. Duct tape is not long-lasting, electrical tape (comes in many colors) is. A quick fix when it comes to electricals is always a bad idea because people generally don't tend to fix things they think are good enough even when they really meant to. Best of all, use heat shrink tubing. If you don't see the difference between electrical tape and duct tape should you really be wiring anything?
Tape of any sort is not allowed as the sole means of making an electrical connection. PERIOD. Wire nuts are used to hold and insulate the connections. Some have a compound inside them for use outside or in damp locations . The use of tape over a wire nut is not required, not necessary and doesn't really do much that the wire nut hasn't already done. It is an old practice from the days of soldered connections. Then came pressure connectors with rubber boots. And now wire nuts. Always twist solid wires together first. Stranded wires can have a slight twist applied to them to if you like, but it's not necessary. If you are putting solid and stranded wires together, place the stranded wire slightly past the end of the solid wire before installing the wire nut. Then tug on it to be sure it got a good grip. If the wire nut is installed properly nothing more needs to be done.
First, no tape should be used as a substitute for proper insulation. Duck tape is entirely different from electrical tape, and will NOT hold very long in situations where electrical tape is recommended.
