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3-way grounded neutral?
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| Replacing a single light fixture that's controlled with two switches.
The light box has a standard black/white/ground supply wire. While
installing I found that the white wire was actually hot (and marked
with black tape) and the black was neutral. The only issue was the
only way I could read 120V from the hot wire was to ground the
circuit. This seems odd to me as none of the three way wiring
diagrams I've seen seem to require the neutral being grounded at the
fixture. The reading from hot to neutral was 60V - not sure if this
means anything or not.
Is this OK or is there something I need to look into here?
Thanks
Doug
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| On Sun, 10 Feb 2008 07:42:42 -0800 (PST), Doug <delphiprog@gmail.com>
wrote:
>Replacing a single light fixture that's controlled with two switches.
>The light box has a standard black/white/ground supply wire. While
>installing I found that the white wire was actually hot (and marked
>with black tape) and the black was neutral. The only issue was the
>only way I could read 120V from the hot wire was to ground the
>circuit. This seems odd to me as none of the three way wiring
>diagrams I've seen seem to require the neutral being grounded at the
>fixture. The reading from hot to neutral was 60V - not sure if this
>means anything or not.
>
>Is this OK or is there something I need to look into here?
>
>Thanks
>Doug
It is legal. Romex comes with one black wire and a white wire. You
assumed the white wire is neutral. It isn't. It is one of the two
wires needed for the switch. The black tape is to tell you that the
wire is the return from the switch and not a neutral.
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| John Grabowski 2008-02-10, 1:25 pm |
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"Doug" <delphiprog@gmail.com> wrote in message
news:1d5dad18-e460-4c02-880c-ff4fab971064@v67g2000hse.googlegroups.com...
> Replacing a single light fixture that's controlled with two switches.
> The light box has a standard black/white/ground supply wire. While
> installing I found that the white wire was actually hot (and marked
> with black tape) and the black was neutral. The only issue was the
> only way I could read 120V from the hot wire was to ground the
> circuit. This seems odd to me as none of the three way wiring
> diagrams I've seen seem to require the neutral being grounded at the
> fixture. The reading from hot to neutral was 60V - not sure if this
> means anything or not.
>
> Is this OK or is there something I need to look into here?
It doesn't sound okay to me. It sounds as though you have no neutral at the
light fixture. The feed for the light fixture should come from one of the
switches. Open them up and see if you have a neutral in there. The feed
for the circuit should also come into one of the switches. It could be the
same switch as the one that contains the light feed or the other switch.
Check to see if you have juice between the white and the black circuit feed.
I suggest using a pigtail light socket with a light bulb instead of a
digital meter.
Another possibility is that this set-up is wired using only two wires
instead of three between switches. In that type of operation the neutral
and hot rotate getting turned off depending on the positions of the wall
switches. Try flipping the switches and see if the polarity changes and you
get 120 volts. This is not the proper way for three-way switches to work as
the hot is off only 50% of the time and the neutral is off the other 50%.
Did the old light fixture work before you replaced it? If so how was it
wired?
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| gfretwell@aol.com 2008-02-10, 1:25 pm |
| On Sun, 10 Feb 2008 11:18:57 -0500, Terry <kilowatt@charter.net>
wrote:
>On Sun, 10 Feb 2008 07:42:42 -0800 (PST), Doug <delphiprog@gmail.com>
>wrote:
>
>
>It is legal. Romex comes with one black wire and a white wire. You
>assumed the white wire is neutral. It isn't. It is one of the two
>wires needed for the switch. The black tape is to tell you that the
>wire is the return from the switch and not a neutral.
Actually the NEC says you use the white, reidentified another color
for the feed to the switch and the switched leg is the black. That way
the luminaire installer is presented with a black hot and a white
neutral. 200.7(C)(2)
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| BobK207 2008-02-10, 1:25 pm |
| On Feb 10, 7:42 am, Doug <delphip...@gmail.com> wrote:
> Replacing a single light fixture that's controlled with two switches.
> The light box has a standard black/white/ground supply wire. While
> installing I found that the white wire was actually hot (and marked
> with black tape) and the black was neutral. The only issue was the
> only way I could read 120V from the hot wire was to ground the
> circuit. This seems odd to me as none of the three way wiring
> diagrams I've seen seem to require the neutral being grounded at the
> fixture. The reading from hot to neutral was 60V - not sure if this
> means anything or not.
>
> Is this OK or is there something I need to look into here?
>
> Thanks
> Doug
Doug-
IMO you need to look into this a little.
The wring to the first switch box should be an un-switched hot
(black), an un-switched neutral (white) & a ground wire to the switch
& the box (if metal) .
The wiring from the first switch box to the second switch box should
be two switched hots (black & red or re-indentifed white), an un-
switched neutral (white) & a ground wire to the switch & the box (if
metal) .
So one needs 4 conductors (including the ground) between the two
switch boxes....here's where some people either get confused or
cheat. Ideally you use a three wire romex (black, red, white,
ground) or a double run of 2 wire Romex.
From the second switch box to the fixture box you should have a
switched hot (black), an un-switched neutral (white) & a ground wire
to the switch & the box (if metal) .
The setup you describe (if I'm understanding it) seems a little
off.
Is the circuit wired with Romex or single conductors (knob & tube OR
wire in conduit)?
Maybe the circuit existed as a single switch & the three way part was
added later.
Be careful, because of the limitations of 2 wire Romex systems, some
people take shortcuts on rewiring or additions that can leave you with
less than safe situations.
per John's comments a light bulb is often better than a meter
The 60v reading might be a result of a poor connection somewhere or a
digital meter giving a false reading reading.
cheers
Bob
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| On Feb 10, 9:40=A0pm, BobK207 <rkaza...@gmail.com> wrote:
> On Feb 10, 7:42 am, Doug <delphip...@gmail.com> wrote:
>
>
>
>
> Doug-
>
> IMO you need to look into this a little.
>
> The wring to the first switch box should be an un-switched hot
> (black), =A0an un-switched neutral (white) & a ground wire to the switch
> & the box (if metal) .
>
> The wiring from the first switch box to the second switch box should
> be two =A0switched hots (black & red or re-indentifed white), =A0an un-
> switched neutral (white) & a ground wire to the switch & the box (if
> metal) .
>
> So one needs 4 conductors (including the ground) between the two
> switch boxes....here's where some people either get confused or
> cheat. =A0 Ideally you use a three wire romex (black, red, white,
> ground) or a double run of 2 wire Romex.
>
> From the second switch box to the fixture box you should have a
> switched hot (black), an un-switched neutral (white) & a ground wire
> to the switch & the box (if metal) .
>
> The setup you describe (if I'm understanding it) =A0seems a little
> off.
>
> Is the circuit wired with Romex or single conductors (knob & tube =A0OR
> wire in conduit)?
>
> Maybe the circuit existed as a single switch & the three way part was
> added later.
>
> Be careful, because of the limitations of 2 wire Romex systems, some
> people take shortcuts on rewiring or additions that can leave you with
> less than safe situations.
>
> per John's comments a light bulb is often better than a meter
>
> The 60v reading might be a result of a poor connection somewhere or a
> digital meter giving a false reading reading.
>
> cheers
> Bob
Bob that info 'could' be misleading?
What it sound like, as mentioned in one of the replies is that black
and white wires go from the ceiling box down to the switch. One of the
wires is the 'live' feed in and the other is the 'switched live'.
Consequently when the switch is 'on' electricity flows down to the
switch through the switch and back up to the 'hot' side of the light
fixture; and the light goes on.
Reading 60 volts may be meaningless; even cheap modern digital meters
can pick up voltages due to capacitance between wires etc. A much
better way to test is to use a regular bulb.
Nothing should be wired to the ground except metal parts of wiring
boxes, ceiling boxes, metal roses etc. the ground is a safety wire.
The ground can, but only 'momentarily' be used for testing; for
example put the test bulb between a wire and ground; if it comes on
all the time (with circuit breaker for that circuit on) it is a 'non-
switched live'. If it goes on and off as you operate the switch it is
a 'switched live'.
Then turn off the circuit breaker and wire the switched live to the
light fixture (or fixtures. Cos some rooms have two or more lights
controlled by the one switch!) Turn breaker back on (or reinsert
fuse) and test.
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| Thanks for all the replies. Looks like a previous post of mine got
lost. Anyway...
I am going to pull out each switch and examine to see if I can
determine exactly what's going on. I will take pictures if I can't
figure it out and post back.
One followup question -
If I am to understand what might be happening is depending on which
switch is switched on, either the white or black wire could be the hot
wire. Is this accurate?
I doubt it was ever a single switch. It's a kitchen light and (with
the exception of the bedrooms) EVERY light in our house is on a 3-way
circuit, including two four ways. As far as how the circuit is wired
(BobK207's comments), everything is wired with standard wiring. I'm
not sure what Romex is. The supply wires in our house are black/white/
bare ground 12 gauge copper covered in what appears to be metallic
sheath (it's silver in color).
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"Doug" <delphiprog@gmail.com> wrote in message
news:6ae4414f-71ae-451a-b5db-b703468dbac2@l16g2000hsh.googlegroups.com...
> Thanks for all the replies. Looks like a previous post of mine got
> lost. Anyway...
>
> I am going to pull out each switch and examine to see if I can
> determine exactly what's going on. I will take pictures if I can't
> figure it out and post back.
>
> One followup question -
>
> If I am to understand what might be happening is depending on which
> switch is switched on, either the white or black wire could be the hot
> wire. Is this accurate?
Anything is possible. At the fixture, you should have an unswitched Neutral
regardless of what color it is. You should be able to determine which wire
because it will give you continuity to the ground conductor or metal box.
Only ungrounded (hot) goes through the switches, then returns to the
fixture. With a light bulb pigtail, test between the hot return wire from
the switch and either ground or neutral, it'll light with the switch "on"
>
> I doubt it was ever a single switch. It's a kitchen light and (with
> the exception of the bedrooms) EVERY light in our house is on a 3-way
> circuit, including two four ways. As far as how the circuit is wired
> (BobK207's comments), everything is wired with standard wiring. I'm
> not sure what Romex is. The supply wires in our house are black/white/
> bare ground 12 gauge copper covered in what appears to be metallic
> sheath (it's silver in color).
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| BobK207 2008-02-10, 8:25 pm |
| On Feb 10, 3:17 pm, Doug <delphip...@gmail.com> wrote:
> Thanks for all the replies. Looks like a previous post of mine got
> lost. Anyway...
>
> I am going to pull out each switch and examine to see if I can
> determine exactly what's going on. I will take pictures if I can't
> figure it out and post back.
>
> One followup question -
>
> If I am to understand what might be happening is depending on which
> switch is switched on, either the white or black wire could be the hot
> wire. Is this accurate?
>
> I doubt it was ever a single switch. It's a kitchen light and (with
> the exception of the bedrooms) EVERY light in our house is on a 3-way
> circuit, including two four ways. As far as how the circuit is wired
> (BobK207's comments), everything is wired with standard wiring. I'm
> not sure what Romex is. The supply wires in our house are black/white/
> bare ground 12 gauge copper covered in what appears to be metallic
> sheath (it's silver in color).
Doug-
Sorry about the use of the term "Romex".....now called NM (non-
metallic cable)
Typically a white, a back & a bare conductor in a plastic sheath (now
yellow for 12ga & cream for 14ga)
I'm guessing that your house is a 50's / 60's unit using BX cable?
cheers
Bob
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| On Sun, 10 Feb 2008 18:43:21 -0500, "RBM" <rbm@noemail.com> wrote:
[color=darkred]
>
>"Doug" <delphiprog@gmail.com> wrote in message
>news:6ae4414f-71ae-451a-b5db-b703468dbac2@l16g2000hsh.googlegroups.com...
>
>Anything is possible. At the fixture, you should have an unswitched Neutral
>regardless of what color it is. You should be able to determine which wire
>because it will give you continuity to the ground conductor or metal box.
>Only ungrounded (hot) goes through the switches, then returns to the
>fixture. With a light bulb pigtail, test between the hot return wire from
>the switch and either ground or neutral, it'll light with the switch "on"
If the light is controlled by 2 switches, then you should be seeing
some red wire too.
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| BobK207 2008-02-10, 8:25 pm |
| On Feb 10, 11:17 am, terry <tsanf...@nf.sympatico.ca> wrote:
> On Feb 10, 9:40 pm, BobK207 <rkaza...@gmail.com> wrote:
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Bob that info 'could' be misleading?
>
> What it sound like, as mentioned in one of the replies is that black
> and white wires go from the ceiling box down to the switch. One of the
> wires is the 'live' feed in and the other is the 'switched live'.
>
> Consequently when the switch is 'on' electricity flows down to the
> switch through the switch and back up to the 'hot' side of the light
> fixture; and the light goes on.
>
> Reading 60 volts may be meaningless; even cheap modern digital meters
> can pick up voltages due to capacitance between wires etc. A much
> better way to test is to use a regular bulb.
>
> Nothing should be wired to the ground except metal parts of wiring
> boxes, ceiling boxes, metal roses etc. the ground is a safety wire.
>
> The ground can, but only 'momentarily' be used for testing; for
> example put the test bulb between a wire and ground; if it comes on
> all the time (with circuit breaker for that circuit on) it is a 'non-
> switched live'. If it goes on and off as you operate the switch it is
> a 'switched live'.
>
> Then turn off the circuit breaker and wire the switched live to the
> light fixture (or fixtures. Cos some rooms have two or more lights
> controlled by the one switch!) Turn breaker back on (or reinsert
> fuse) and test.
Terry-
I composed a reply to your comments but lost it when my PC froze. 
I'm pretty sure from Doug's original post there is only a white
(tagged with black) & a black wire in the fixture box under
consideration.
If Doug's only got two wires in the box & the tagged white is hot (&
switched)
and the black wire is in fact the neutral (0 volts to ground) ...then
he's got some color coding issues.
I'm not sure I'm understanding your comment
[color=darkred]
and white wires go from the ceiling box down to the switch. One of the
wires is the 'live' feed in and the other is the 'switched live'.
Consequently when the switch is 'on' electricity flows down to the
switch through the switch and back up to the 'hot' side of the light
fixture; and the light goes on. <<<<<
if he's only got two wires and one goes to the switch & the other
comes back....he's got no hot feed & no neutral. ???
It seems to me for a switch leg to exist he'd need four wires in the
box; hot in, hot to switch, switched hot back from switch & of course
the neutral.
We'll see what Doug discovers & reports back.
cheers
Bob
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>
> Doug-
>
> Sorry about the use of the term "Romex".....now called NM (non-
> metallic cable)
>
> Typically a white, a back & a bare conductor in a plastic sheath (now
> yellow for 12ga & cream for 14ga)
>
> I'm guessing that your house is a 50's / 60's unit using BX cable?
>
> cheers
> Bob
Hey Bob,
House was built in 1963. Again, not sure what the cable is called,
sorry for the ignorance. Descriptions I found on the internet of BX
cable appear to have a solid metal sheath. This has more a a cloth-
like metallic texture (i know that's a bad description, sorry). I
can't get pictures until tomorrow evening so I will post back then.
Really appreciate everyone's help on this.
Doug
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"Terry" <kilowatt@charter.net> wrote in message
news:ti7vq3l3d2v87sciupsce36n147o7rqu42@4ax.com...
> On Sun, 10 Feb 2008 18:43:21 -0500, "RBM" <rbm@noemail.com> wrote:
>
> If the light is controlled by 2 switches, then you should be seeing
> some red wire too.
Only between the switches. My understanding is that he only has two
conductors and ground at the fixture. No?
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| On Feb 10, 9:36 pm, "RBM" <r...@noemail.com> wrote:
> "Terry" <kilow...@charter.net> wrote in message
>
>
>
> Only between the switches. My understanding is that he only has two
> conductors and ground at the fixture. No?
Hey RBM
The supply wire to the fixture contains three 12 gauge copper wires in
a single metallic cloth sheath:
1 black wire
1 white wire with a piece of black electrical tape stuck to it
1 bare ground
Like I said I'll have pictures tonight. Thanks for all the help.
Doug
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