On Thu, 12 Dec 2019 17:50:25 -0500, wrote:

On Thu, 12 Dec 2019 16:22:23 -0500, Clare Snyder
wrote:

On Thu, 12 Dec 2019 14:44:05 -0500, wrote:

On Thu, 12 Dec 2019 12:58:07 -0500, Ralph Mowery
wrote:

In article , lid says...

I found several of those around here, when I installed ceiling fans. The
box would have a bundle of black wires and a bundle of white wires. The
black bundle would usually have one white (for the switch loop) in it.




I don't know the code now.

Way back it was common to use the same wire that had a black and white,
bare wire for everything. So going to the wall switch you would have
the black, a white that should be marked to black usually by tape and
the bare. When that wire gets back to the junction box, the white wire
should be marked black. The black marking may or may not be done
depending on how sloppy the electrician and inspectors are.

That is because the black ( hot ) wire goes to the switch and is broken
to cut off the current and back to the light. A netural wire should not
be switched.

Not that long ago, there was not a requirement to reidentify the white
wire in a switch loop. That is where the standard of using the white
for the hot in the loop started. Then at the light the user would be
presented with a black (switched) wire for the luminaire and the
normal white neutral. It was always polite to reidentify this wire but
not required.

The rule changed in 1999 and now you have to reidentify it. Since
adoption by the AHJ can take years, there are probably still houses
built in 2002-3 that were still under the 96 code.
I believe marking was required in CANADIAN code as far back as at
least 1969. I know when working with my dad back then I had to tape
them. Black heat shrink tubing made the job easier - as did using
electric heating cable (220 volt) (red/black) for switch drops in
later years.

It was required for things other than switch loops here too (240v
circuits mostly). The 99 change added switch loops to the requirement.
Two wire cable without a white wire was pretty rare, particularly on a
residential sparky's truck. That is why they allow reidentifying the
white wire in a cable. You can't do it if you are pulling discrete
conductors. You need to use the appropriate color wire until you get
up to 4 ga when anything but black is harder to find. I do have some
#1 in red, black and white tho so it is not impossible to get.
Electric heat was pretty common in residential use, so a residential
sparky could be expected to have the cable available - but it was
odten AWG12 instead of 14 - - - Discrete wire in residential use here
in Ontario is excedingly rare outside of large MURBs