[PLUG-TALK] electrical wiring question

[Pete Lancashire]

I'd like to see a photo or two.

And I'd like the see any identification on a the cable with 1xBlack
and 2xWhite. For residential electrical wire, I'm unaware of any cable
with two white wires.


http://www.how-to-wire-it.com/wiring-a-3-way-switch.html

On Fri, May 27, 2016 at 12:10 PM, Denis Heidtmann
<denis.heidtmann at gmail.com> wrote:
> (top posting)
>
> If the power feed is at the light and a three-wire cable goes from  the
> light to the switch and the three-wire cable has black and two whites then I
> understand.  Was such a three-wire cable made?  (I saw no red in the switch
> box.)
>
> -Denis
>
>
> On Fri, May 27, 2016 at 11:21 AM, Pete Lancashire <pete at petelancashire.com>
> wrote:
>>
>> The wire is sometimes called a traveler. NEC allows this one exception
>> for wires that are white. It REQUIRES that the wire must be identified
>> ... tape, permanent marker, paint etc.
>>
>> You can not have more then one 'white' traveler.
>>
>> Again NEC only allows this for lighting. There are some jurisdictions
>> that do not allow it.
>>
>> Although it is in the Grounding section 200.7 (c) .
>>
>> 200.7 Use of Insulation of a White or Gray Color or with Three
>> Continuous White Stripes
>> (C) Circuits of 50 Volts or More. The use of insulation that is white
>> or gray or that has three continuous white stripes for other than a
>> grounded conductor for circuits of 50 volts or more shall be permitted
>> only as in (1) and (2).
>> (1) If part of a cable assembly that has the insulation permanently
>> reidentified to indicate its use as an ungrounded conductor by marking
>> tape, painting, or other effective means at its termination and at
>> each location where the conductor is visible and
>> accessible............
>>
>>
>>
>> On Fri, May 27, 2016 at 8:41 AM, John Jason Jordan <johnxj at comcast.net>
>> wrote:
>> > On Fri, 27 May 2016 08:03:46 -0700
>> > Denis Heidtmann <denis.heidtmann at gmail.com> dijo:
>> >
>> >>Is  there any legitimate reason to connect a black and white wire
>> >>together?  I have been trying to conjure some historical reason for
>> >>this wiring, but cannot.  In hindsight I desperately wish I had spent
>> >>some time studying the situation.
>> >
>> > This happens all the time, especially in switches, and is perfectly
>> > acceptable. However, electricians normally carry rolls of tape in
>> > common colors (black, white, red) because it is considered good
>> > practice to use tape to 'change the color' of a wire inside the box
>> > just before it connects to the appliance.
>> >
>> > The problem is that household wire comes with a black, a white, and a
>> > bare (earth ground) wire. (If three-conductor wire, the extra hot wire
>> > is red.) When wiring a switch the black and white wires travel to the
>> > light, and they are both hot wires, so one should wrap a bit of black
>> > tape over the white wire to signal to future electricians 'this wire is
>> > white, but it's hot.' Having said that, I think the convention of using
>> > tape to change the color of a wire is recent, because I constantly find
>> > situations in old houses where it was not done.
>> >
>> > I should add that it is good practice (although not required) to have
>> > power in every box, including switch boxes. I always do so because then
>> > I can later (if desired) swap out the switch for a switch+outlet
>> > appliance. That might explain the wire nuts that you saw in the box.
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