"TimR" wrote in message
...
On Saturday, October 31, 2015 at 12:26:04 PM UTC-4, The
connection was on #12 solid, and the mechanic had twisted the wires before
putting on the wire nut, but they didn't make good enough contact, it's
very hard to twist solid wire tightly enough.

I put them back together, exactly straight and exactly the same length,
not twisted, before I put the wire nut back on, and it was still doing
fine when I moved out several years later.

I concluded stranded wire should always be twisted and solid never, but
that's just my personal opinion.

Working at a large company and installing lots of wire nuts of all sizes, I
never twisted any wires. The instructions for some say they can be
twisted, but not needed. If correctly installed, the wires will twist when
the nut goes on. I never reuse a wire nut. I never taped any except when
installed on motors or something that viberates. Probably not needed, but
just did it sometimes.