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Small wiring puzzle Aaron Fude 05-10-2008
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Posted by Aaron Fude on May 10, 2008, 11:41 pm
Metspitzer, I appreciate what you are saying, and that's what it
should be, but that's just not what it is and I'd like to figure it
out.

So here's additional information.

And the fixture:
1. The black wire is definitely hot.
2. The voltmeter shows zero voltage across the black and the white
when diconnected at the switch.

"In between":
With the circuit off, I performed a connectivity test by testing for
resistance. When I touched the two wires at the fixture, the
resistance went down to zero when measuring at the switch.

At the switch:
I. Both wires dead when wires not touching at the fixture.
II. With wires touching at the fixture, the white wire is hot and the
voltage across the wires shows 120V.

Does that help shed light on the situation?

Thanks!

Posted by terry on May 11, 2008, 3:04 am
>
>
>
>
>
>
>
>
>
...
> > >>>> I'm sure you guys will crack it instantly.
>
> > >>>> I'm replacing a light and the switch that controlled it. I removed =
the
> > >>>> switch first. The switch connected a black and a white wire that ca=
me
> > >>>> in the same sheath. The white one was hot. (I know that sometimes t=
his
> > >>>> means something, but what?)
>
> > >>>> Then when I removed the light I discovered that it, too, had a blac=
k
> > >>>> and a white wire connected to it, and the black one is hot. Now tha=
t
> > >>>> the light is disconnected, the black white is still hot, but the wi=
re
> > >>>> that used to be connected to the switch is now dead.
>
> > >>>> There are no other wires in either electrical box.
>
> > >>>> I'm racking by brain, but can't figure out how everything was
> > >>>> connected.
>
> > >>>> Many thanks in advance!
>
> > >>>> Aaron
>
> > >>> I'm thinking that there is another junction box somewhere where thes=
e
> > >>> wires could be connected. =A0Is there another light fixture in the s=
ame
> > >>> room? =A0Is there an accessible attic above so you can go see if the=
re is
> > >>> a
> > >>> junction box up there? =A0Did an electrical box get buried during a
> > >>> remodel?
>
> > >>I agree, the op either missed the second cable and splice in one of th=
e
> > >>junction boxes or there is obviously a third box, and they mistakenly
> > >>broke
> > >>the neutral through the switch>
>
> > > Sounds like to me he is just trying to get a voltage reading across
> > > the switch.
>
> > > If he took a switch out he would only have 2 wires to put back. =A0You=

> > > can't really mess it up.
>
> > > When he took the light down, there is only 2 wires to put back too.
>
> > > Seems like he is mistaken of the meter readings.
>
> > I think he's just trying to figure how it works, not so much, how to put=
it
> > back. As you said, he really can't go wrong. I belive he's thinking that=

> > with the switch wires disconnected, he shouldn't still have a hot wire a=
t
> > the light, which is correct, except for when the neutral was switched
> > instead of the hot
>
> > - Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -
>
> Hi,
>
> To clarify matters - yes, I'm just trying to figure out how it works,
> not how to put it back together. And I still don't get it.
>
> There are *only* to wires in each electrical box. I'm sure I did not
> miss anything, because I have now removed the electrical boxes. Each
> of the two wires came from a single romex.
>
> So Cliff's suggestion was mostly likely, but that is not it. So I am
> still puzzled.
>
> One thing I am thinking is that I've been using a cheapo pen-like
> voltage detector. Maybe my readings are wrong. I will go back and use
> something a little bit more refined.- Hide quoted text -
>
> - Show quoted text -

Use a bulb not a tester. Even cheap testers can pick induced voltages
on disconnected from adjacent working wires.

Sounds like two possibilities.
1) As some have pointed out the switch may be wired into the white
(neutral) side of the line to to light. However more likely it may
just a confusion of colours by whoever wired it previously.
2) In order to switch ceiling lights on and off, the two wires down to
the switch could (are likely to) be:
a) A live lead (s'posed to be black but may not be) from the supply.
b) A wire that connects to other side of the switch. This lead
although it may be white is called a 'Switched Live'. So that when the
switch is ON there is voltage that wire goes to the light fixture.
At the light fixture the neutral (white) side should be solid back to
the supply (neutral) and the 'switched live, which may be white
possibly marked with tape or nail polish in some way!**) provides
switched voltage to the (live wire) of the light.
Unlikely to be any neutral wires at all in the switch box. 'Usually'
all neutrals up in the ceiling run to the light fixtures.
Some jurisdictions suggest that switched live be red not white but
usually accept some form of marking of a white wire as a 'switched
live'. So one may see white/black from fuse panels to each ceiling
fixture but red blacks down to each switch. Where blacks are live and
the reds are switched lives!

Posted by John Grabowski on May 11, 2008, 8:48 am

>
>
>
>
>
>
>
>
> >>>> I'm sure you guys will crack it instantly.
>
> >>>> I'm replacing a light and the switch that controlled it. I removed
> >>>> the
> >>>> switch first. The switch connected a black and a white wire that came
> >>>> in the same sheath. The white one was hot. (I know that sometimes
> >>>> this
> >>>> means something, but what?)
>
> >>>> Then when I removed the light I discovered that it, too, had a black
> >>>> and a white wire connected to it, and the black one is hot. Now that
> >>>> the light is disconnected, the black whire is still hot, but the wire
> >>>> that used to be connected to the switch is now dead.
>
> >>>> There are no other wires in either electrical box.
>
> >>>> I'm racking by brain, but can't figure out how everything was
> >>>> connected.
>
> >>>> Many thanks in advance!
>
> >>>> Aaron
>
> >>> I'm thinking that there is another junction box somewhere where these
> >>> wires could be connected. Is there another light fixture in the same
> >>> room? Is there an accessible attic above so you can go see if there is
> >>> a
> >>> junction box up there? Did an electrical box get buried during a
> >>> remodel?
>
> >>I agree, the op either missed the second cable and splice in one of the
> >>junction boxes or there is obviously a third box, and they mistakenly
> >>broke
> >>the neutral through the switch>
>
> > Sounds like to me he is just trying to get a voltage reading across
> > the switch.
>
> > If he took a switch out he would only have 2 wires to put back. You
> > can't really mess it up.
>
> > When he took the light down, there is only 2 wires to put back too.
>
> > Seems like he is mistaken of the meter readings.
>
> I think he's just trying to figure how it works, not so much, how to put
> it
> back. As you said, he really can't go wrong. I belive he's thinking that
> with the switch wires disconnected, he shouldn't still have a hot wire at
> the light, which is correct, except for when the neutral was switched
> instead of the hot
>
>
>
> - Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -


Hi,

To clarify matters - yes, I'm just trying to figure out how it works,
not how to put it back together. And I still don't get it.

There are *only* to wires in each electrical box. I'm sure I did not
miss anything, because I have now removed the electrical boxes. Each
of the two wires came from a single romex.

So Cliff's suggestion was mostly likely, but that is not it. So I am
still puzzled.

One thing I am thinking is that I've been using a cheapo pen-like
voltage detector. Maybe my readings are wrong. I will go back and use
something a little bit more refined.



Use a pigtail socket and light bulb for testing.


Posted by CJT on May 11, 2008, 11:34 am
John Grabowski wrote:

>
>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> >>>> I'm sure you guys will crack it instantly.
>>
>> >>>> I'm replacing a light and the switch that controlled it. I
>> removed >>>> the
>> >>>> switch first. The switch connected a black and a white wire that
>> came
>> >>>> in the same sheath. The white one was hot. (I know that sometimes
>> >>>> this
>> >>>> means something, but what?)
>>
>> >>>> Then when I removed the light I discovered that it, too, had a black
>> >>>> and a white wire connected to it, and the black one is hot. Now that
>> >>>> the light is disconnected, the black whire is still hot, but the
>> wire
>> >>>> that used to be connected to the switch is now dead.
>>
>> >>>> There are no other wires in either electrical box.
>>
>> >>>> I'm racking by brain, but can't figure out how everything was
>> >>>> connected.
>>
>> >>>> Many thanks in advance!
>>
>> >>>> Aaron
>>
>> >>> I'm thinking that there is another junction box somewhere where these
>> >>> wires could be connected. Is there another light fixture in the same
>> >>> room? Is there an accessible attic above so you can go see if
>> there is
>> >>> a
>> >>> junction box up there? Did an electrical box get buried during a
>> >>> remodel?
>>
>> >>I agree, the op either missed the second cable and splice in one of the
>> >>junction boxes or there is obviously a third box, and they mistakenly
>> >>broke
>> >>the neutral through the switch>
>>
>> > Sounds like to me he is just trying to get a voltage reading across
>> > the switch.
>>
>> > If he took a switch out he would only have 2 wires to put back. You
>> > can't really mess it up.
>>
>> > When he took the light down, there is only 2 wires to put back too.
>>
>> > Seems like he is mistaken of the meter readings.
>>
>> I think he's just trying to figure how it works, not so much, how to
>> put it
>> back. As you said, he really can't go wrong. I belive he's thinking that
>> with the switch wires disconnected, he shouldn't still have a hot wire at
>> the light, which is correct, except for when the neutral was switched
>> instead of the hot
>>
>>
>>
>> - Hide quoted text -
>>
>> - Show quoted text -- Hide quoted text -
>>
>> - Show quoted text -
>
>
>
> Hi,
>
> To clarify matters - yes, I'm just trying to figure out how it works,
> not how to put it back together. And I still don't get it.
>
> There are *only* to wires in each electrical box. I'm sure I did not
> miss anything, because I have now removed the electrical boxes. Each
> of the two wires came from a single romex.
>
> So Cliff's suggestion was mostly likely, but that is not it. So I am
> still puzzled.
>
> One thing I am thinking is that I've been using a cheapo pen-like
> voltage detector. Maybe my readings are wrong. I will go back and use
> something a little bit more refined.
>
>
>
> Use a pigtail socket and light bulb for testing.

When you made your determination that the white wire from the switch
was hot, was the light socket still connected? If so, you were just
measuring the line voltage through the bulb. Done properly, the
white wire to a switch should have a black marking to signal that it,
too, has the potential (no pun intended) to be hot.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

Posted by Cliff Hartle on May 10, 2008, 9:23 pm
Here is what you have.

http://www.indepthinfo.com/wire-switch/light-switch.shtml

The white wire in the switch box should have been marked with black tape or
sharpie. You'll see that in the picture that the white wired is marked this
way.
--

> I'm sure you guys will crack it instantly.
>
> I'm replacing a light and the switch that controlled it. I removed the
> switch first. The switch connected a black and a white wire that came
> in the same sheath. The white one was hot. (I know that sometimes this
> means something, but what?)
>
> Then when I removed the light I discovered that it, too, had a black
> and a white wire connected to it, and the black one is hot. Now that
> the light is disconnected, the black whire is still hot, but the wire
> that used to be connected to the switch is now dead.
>
> There are no other wires in either electrical box.
>
> I'm racking by brain, but can't figure out how everything was
> connected.
>
> Many thanks in advance!
>
> Aaron



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