Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

3-way switches -- old house wiring

1,471 views
Skip to first unread message

TomR

unread,
Nov 24, 2013, 3:25:16 PM11/24/13
to
I am trying to solve a 3-way switch circuit issue in an old house. The
wiring in the house is old, and it is either knob and tube wiring or
whatever came after that and before "Romex" etc. There are no ground wires
visible anywhere in either circuit, and everything is so dusty and dirty
that I can't tell what is a white wire and what is a black wire etc.

And, to be more precise, there are actually two different 3-way switch
circuits that I am trying to get resolved at the same time.

Downstairs, near the front door entrance, the are two 3-way switches -- one
of the 3-way switches controls the downstairs living room ceiling light.
The other 3-way switch controls the hallway light that is outside of the
upstairs bedrooms.

At the top of the stairs, there are two 3-way switches -- one of those 3-way
switches controls the downstairs living room ceiling light, and the other
3-way switch controls the hallway light that is outside of the upstairs
bedrooms.

I can tell which 3-way switch (upstairs and downstairs) is for the living
room ceiling light, and which one (upstairs and downstairs) is for the
hallway light.

To make things a little more complicated, the whole setup was intentionally
temporarily wired incorrectly a few years back because I couldn't figure out
how to get things working correctly and I needed a way to at least be able
to turn the living room light and the hallway light on and off -- even
though the 3-way switch function was disabled in the process. In other
words, I temporarily have it that only one switch controls each light. It's
a long story why I did that, but that is not important now.

Now, here's the story on the wiring: Coming into each of the 3-way switch
boxes upstairs, and each of the 3-way switch boxes downstairs, are 3 exactly
wires. There are no other wires in each switch box -- no neutrals wired
together etc. -- just 3 wires in each box and no other wires leaving the
boxes etc.

I found the following link to various 3-way switch wiring options:
http://www.easy-do-it-yourself-home-improvements.com/3-way-switch-wiring-diagram.html .



Based on what I have (just 3 wires in each box) I am assuming that the two
circuits are wired as shown in Option #8 on that link. The power source
appears to go to each light, and from each light, the switch wires run to
each of the switches. I concluded that because I don't see any other wiring
options where there are ONLY 3 wires in each switch box.



And, now for the problem: I need to put new 3-way switches in, both in the
upstairs boxes and in the downstairs boxes. The downstairs boxes have push
button 3-way switches that are broken, so they need to be replaced. I need
to figure out how to rewire the system, using the existing wires, and
connecting those wires to the four new 3-way switches that I bought.



I am thinking that, with the power on, but the switches removed, I can
figure out which wire is the hot "source" wire that goes to one of the
switches for each circuit. I can connect that hot wire to the hot common
for each of those two switches, and connect the other two wires in each of
those boxes to the "traveler" screws on those switches.



But, then, when I go to the other switch at the other end of each circuit,
how can I tell which wire in each of those boxes goes to the hot "common"
screw? Once I know that, I can connect that hot common wire to the black
"common" screw and just connect the other two wires to the traveler screws.
But, how do I know which of the 3 wires goes to the hot "common" screw?


Metspitzer

unread,
Nov 24, 2013, 4:02:41 PM11/24/13
to
Since there are only 3 wires at each location, that makes it easy,
assuming everything was wired correctly originally. You need a no
contact voltage tester like this:
http://www.specialized.net/Specialized/VC200-SPCtelco-AC-Non-Contact-Voltage-DetectorTester-501000VAC-7281.aspx

Take one set of 3 ways and disconnect all of the wires. Turn the
power on and test all of the wires. Only 1 of the 6 should be hot.
When you find it, turn the power back off and mark that wire with
black tape.

Wire this location with a 3-way using the wire with black tape as the
common. The order of the other two don't matter.

Turn the power back on and go to the 3 wires at the other switch. Only
1 of those 3 will be hot. Get a helper to flip the other switch. The
original hot wire will go dead another wire will become hot. Turn the
power back off. The wire that is never hot at that switch location
will be the common. Mark it with black tape and wire the other 3 way.

That should work.

Retired

unread,
Nov 24, 2013, 4:13:46 PM11/24/13
to

>
>
>
> But, then, when I go to the other switch at the other end of each circuit,
> how can I tell which wire in each of those boxes goes to the hot "common"
> screw? Once I know that, I can connect that hot common wire to the black
> "common" screw and just connect the other two wires to the traveler screws.
> But, how do I know which of the 3 wires goes to the hot "common" screw?
>
>


I would suggest by process of elimination. Using the pic at Option 8.

After you identify the incoming Hot, get first switch installed, then
the "red" or "white" at the 2nd switch will become hot, depending on
position of first switch. The black at the 2nd switch will stay cold
regardless of pos. of 1st switch.

Of course you want all the "loose" wires clear and not touching anything.

Do not assume that the first incoming Hot is in the downstairs boxes !!

bob haller

unread,
Nov 24, 2013, 6:14:53 PM11/24/13
to
probably best to safely abandon the current wiring and replace it with all new..

messing with knob and tube isnt really a good idea.......

Caulki...@work.com

unread,
Nov 24, 2013, 6:42:26 PM11/24/13
to
On Sun, 24 Nov 2013 15:14:53 -0800 (PST), bob haller <hal...@aol.com>
wrote:

>probably best to safely abandon the current wiring and replace it with all new..
>
>messing with knob and tube isnt really a good idea.......

Why is is not a good idea? K+T wires always worked, and they were quite
durable considering how long they last. If the wall plaster is removed,
such as during a remodel, by all means replace the wiring, but there is
no sense ripping open walls as long as the old wiring is still in good
shape, especially for just simple lighting. The downfall of K+T wiring
has always been that the color came off the wires, lack of a ground, and
unsafe *IF* people would put oversize fuses in (which was far too
common). If you still have fuses, by all means replace the fuse box
with modern breakers. Or at least use the proper fuse. But for low
amperage lighting, particularly if modern CFL or LED lights are used,
there is no reason to have to rip a house apart to replace K+T wiring.

You can buy colored electrical tape. Make your job easier by putting
the proper colored tape on each wire. Black - White - Red.
Then do as others have told you in this thread to identify which are the
HOT wires.

Here are some diagrams:

http://www.electrical-online.com/wp-content/uploads/2010/11/3-way-switch.jpg
http://home-garden.blurtit.com/var/question/q/q3/q30/q303/q3032/q303266_295318_3_way_wiring_1.jpg

TomR

unread,
Nov 24, 2013, 8:21:35 PM11/24/13
to
"Metspitzer" <Kilo...@charter.net> wrote in message
news:r0p499labl5pgnbem...@4ax.com...
Thanks Metspitzer. Great explanation, and I think that will do the trick.
I have a no contact voltage tester, and I was already doing a little testing
with it on Friday afternoon; but I decided that I should do some more
searching and research first and then get back to it this coming week and do
it the right way. It never occurred to me that the wire on the second 3-way
switch that never gets hot (when doing what you said) would be the one that
is the common. But, that makes sense, and I think it will work.


TomR

unread,
Nov 24, 2013, 8:22:57 PM11/24/13
to
"Retired" <Ret...@home.com> wrote in message
news:kvydnRIgB6Cj8Q_P...@giganews.com...
Makes sense. Thanks.


TomR

unread,
Nov 24, 2013, 8:25:45 PM11/24/13
to
<Caulki...@work.com> wrote in message
news:8p2599d87ttse7iks...@4ax.com...
> On Sun, 24 Nov 2013 15:14:53 -0800 (PST), bob haller <hal...@aol.com>
> wrote:
>
>>probably best to safely abandon the current wiring and replace it with all
>>new..
>>
>>messing with knob and tube isnt really a good idea.......

> Why is is not a good idea? K+T wires always worked, and they were quite
> durable considering how long they last. If the wall plaster is removed,
> such as during a remodel, by all means replace the wiring, but there is
> no sense ripping open walls as long as the old wiring is still in good
> shape, especially for just simple lighting. The downfall of K+T wiring
> has always been that the color came off the wires, lack of a ground, and
> unsafe *IF* people would put oversize fuses in (which was far too
> common). If you still have fuses, by all means replace the fuse box
> with modern breakers. Or at least use the proper fuse. But for low
> amperage lighting, particularly if modern CFL or LED lights are used,
> there is no reason to have to rip a house apart to replace K+T wiring.

I agree. No need to build a new house. I just want to get these 3-way
switches working correctly.

> You can buy colored electrical tape. Make your job easier by putting
> the proper colored tape on each wire. Black - White - Red.
> Then do as others have told you in this thread to identify which are the
> HOT wires.

Makes sense.

bob haller

unread,
Nov 24, 2013, 8:27:26 PM11/24/13
to
unmolested K&T is marginally ok. but tapping into it, modifying it, can add new hazards. a good friend had a small home fire where a solder joint detoriated and overheated, fortunately he cauht it just in time. it was smoldering he could of lost the entire house. his dad had soldered that joint over 30 years ago....

which is why i said just replace the entire thing..... all the 3 way light switches etc, that the OP said he had intentionally miss wired

Metspitzer

unread,
Nov 24, 2013, 8:29:19 PM11/24/13
to
On Sun, 24 Nov 2013 20:21:35 -0500, "TomR" <To...@tomrljp2hg.mht>
wrote:
You are welcome.
Let us know.

Caulki...@work.com

unread,
Nov 24, 2013, 9:06:11 PM11/24/13
to
On Sun, 24 Nov 2013 20:21:35 -0500, "TomR" <To...@tomrljp2hg.mht> wrote:

>Thanks Metspitzer. Great explanation, and I think that will do the trick.
>I have a no contact voltage tester, and I was already doing a little testing
>with it on Friday afternoon; but I decided that I should do some more
>searching and research first and then get back to it this coming week and do
>it the right way. It never occurred to me that the wire on the second 3-way
>switch that never gets hot (when doing what you said) would be the one that
>is the common. But, that makes sense, and I think it will work.

Here is a tip that might help. On K+T wiring, the ceiling boxes were
almost always the power source. The reason is that back then, lighting
was the top priority. Outlets were rare and few and even those were
mostly for lamps. So, almost all the power source wires went across a
ceiling. The light you want to control most likely has the "source"
wires.

Therefore, both common wires on one switches go to the light fixture
box. One to the bulb, the other to the "source". If nothing else
works, get a multimeter (Walmart for $10) and some cheap wire long
enough to go from both switches to the fixture. Set meter to OHMS, Shut
off power in house, and remove the wires from both switches. Attach one
lead from the meter to the wire going to the bulb. (alligator clips
help). Use your long wire on the other meter lead, and find the one in
the switch box that matches (meter will indicate continuity). Then do
the same for the source wire. Those two are the common wires.

I always have a multimeter and a 50ft roll of single strand automotive
or doorbell wire handy to do this sort of thing. I worked many years
doing handyman work and mostly in old homes that had K+T wiring. Over
the years that wiring was changed, modified, and/or simply disconnected
and even cut off, when a wall or doorway was added or something. Some
of those jobs were a total nightmare, but I always managed to get the
wires to work. What complicated those homes was that some were huge
single family homes that originally had servant quarters and were built
for the wealthy in those days. Then they were changed into multi-family
apartments and supposedly rewired so each apartment had it's own
electric meter. More often than not, apartments had the wrong meter
feeding part of their apt., and tenants would complain that their
electric bill was very high, while others paid nearly nothing. It would
be my job to straighten out this mess, and a mess it was..... I'd shut
off the power to that apt. and suddenly hit a live wire, or disconnect
something in another apt. I recall one huge home taking me over 2 weeks
of 8 hour days to get it all straightened out. But I'll admit now, I
liked the challenge!


TomR

unread,
Nov 24, 2013, 9:18:46 PM11/24/13
to
"Metspitzer" <Kilo...@charter.net> wrote in message
news:vt9599td2pi2fa03b...@4ax.com...
I will do that.



Caulki...@work.com

unread,
Nov 24, 2013, 9:23:49 PM11/24/13
to
On Sun, 24 Nov 2013 17:27:26 -0800 (PST), bob haller <hal...@aol.com>
wrote:
-------

Yea, but he's not tampering with the actual wires, just moving them
around inside a box to get them on the right screws on the switches.

That solder joint was apparently not soldered well in the first place.
Soldered wires were some of the best connections made, if they were done
properly. I also would bet that they had a 30A fuse in use on some #14
wire, and had plugged in an electric heating device.

When I had to tap into existing K+T wiring on my jobs, I would install a
box and use wirenuts. But on a few jobs, I did also solder them when it
was impractical to install a box, such as in an attic where the wires
did not provide enough length to use a box, and I only needed to add a
tap to provide another light. I'd just bare the wires, attach some
romex, and solder them and apply tape. Safety was always a main
concern, but customers were not willing to pay to have their whole house
ripped apart, and repaired just to add a ceiling fan or some track
lights.

By the way, here is another tip I forgot to mention. Colored heat
shrink tubing works great to color the wires the way they should be.
Costs a little more than tape, but is real easy to use, and even
protects the wires from fraying on their ends which that old cloth wire
was known to do.

micky

unread,
Nov 24, 2013, 10:13:43 PM11/24/13
to
On Sun, 24 Nov 2013 15:25:16 -0500, "TomR" <To...@tomrljp5.lhd> wrote:

>I am trying to solve a 3-way switch circuit issue in an old house. The
>wiring in the house is old, and it is either knob and tube wiring or
>whatever came after that and before "Romex" etc. There are no ground wires
>visible anywhere in either circuit, and everything is so dusty and dirty
>that I can't tell what is a white wire and what is a black wire etc.

I'm confused, so all I can say is write things down, to make a diagram
of what wires you know about, at least the swtiches and an inch of
wire whereever there's a wire, indicating what color every wire is
(the real color too, in case any wire has been painted.) .

And make a chart of what they should do. LIke
Switch 1, turn on lights A and B.

Then start enlarging the chart and the wiring diagram to show what
wires you would need to make it do what the chart says you want it to
do.

When you're not sure which switch is for which, see which actual
switch and wires is closer to which item on the chart. Also, normally
when both switches are near the bottom of the stairs, the switch for
the living room will be closer to the living room than the switch for
the stairs will be.


When I bought my house, the front hall was miswired so one switch only
worked if the other switch was in the right position.

And of the switches by the stairs. the one closer to the basement
stairs controlled the landing near the second floor. The switches
worked but they were in the wrong place.

The electrician lived in the n'hood. A house might have been part of
his payment for doing the wiring. You coudl tell his house because
it had more lights than the rest of us, and he had a vent from the
range hood above his sliding glass door. (For the rest of us, the air
went through a filter and right back into the kitchen)

Anyhow, I saw him at a party 10 or 15 years after he'd wired our
houses, and I told him about the two mistakes. I thought he'd think
it was funny after all these years -- I thought it was funny when I
had to fix them --, but I was totally wrong. He was annoyed, didn't
believe me iirc, and I was sorry I said anything.

micky

unread,
Nov 24, 2013, 10:58:31 PM11/24/13
to
On Sun, 24 Nov 2013 17:42:26 -0600, Caulki...@work.com wrote:

>The downfall of K+T wiring
>has always been that the color came off the wires, lack of a ground, and
>unsafe *IF* people would put oversize fuses in (which was far too
>common).

I lived for 12 years in a 1930 apartment building in Brooklyn. It had
fuses of course, but the owner had put Fuzestat (spelling??) sockets
in each fuse socket, in the basement and in each of the 49 apartments.

Blue was 15 amps, and only a 15 amp Fuzestat fuse would screw into a
15-amp Fuzestat socket. The threads were at the wrong angle or too
narrow for other size fuses. The Fuzestat socket had raspy teeth so
that unscrewing one from the fuse socket it was in was hard to do.

I think 20 amps was orange. Each apartment got 20 amps in a basement
fuse, and one or two 15 amp fuses in the apartment itsellf. My
6-room 3-bath apartment ran on 20 amps, which was enough, even most of
the time with a small air conditioner. .

This all kept any idiot tenants from putting in fuses that were bigger
than they should be. They were more expensive, maybe a lot more,
than regular fuses, but worth it. In my case, the tenant paid for
them.

TomR

unread,
Nov 25, 2013, 11:16:56 AM11/25/13
to
Interesting info. In my case, the building has a modern circuit breaker
panel and a lot of newer wiring with grounded 3-prong outlets etc. But,
some of the circuits -- such as these 3-way switches -- are on the old
wiring.


Metspitzer

unread,
Nov 25, 2013, 1:55:02 PM11/25/13
to
On Sun, 24 Nov 2013 15:25:16 -0500, "TomR" <To...@tomrljp5.lhd> wrote:

http://imgur.com/mlB47zL
I marked what should be going on. 1 (common) will be hot all the
time. a and b will be the travelers and 2 (common) will go to the
light.
(BTW the color code on the ledger is wrong.) White is a traveler, not
common.

Rick

unread,
Nov 25, 2013, 2:25:14 PM11/25/13
to

"TomR" <To...@tomrljp5.lhd> wrote in message
news:l6tnam$asq$1...@dont-email.me...
Given the age of the house and wiring method, keep in mind there may be a
possibility it's a "California 3 way"

Rick

unread,
Nov 25, 2013, 2:42:54 PM11/25/13
to

"Rick" <itsno...@gmail.com> wrote in message
news:IKCdnTe6eu6OOQ7P...@giganews.com...
A variation, with both hots on same leg



H--------o o--------H
o--------light----------o

N--------o o--------N

Metspitzer

unread,
Nov 25, 2013, 2:46:26 PM11/25/13
to
On Mon, 25 Nov 2013 14:42:54 -0500, "Rick" <itsno...@gmail.com>
wrote:
I know there is always that possibility, but since I worked in mostly
hospitals I have never encountered one. If he finds a hot at each
switch with everything disconnected, that should tell us.

TomR

unread,
Nov 25, 2013, 4:16:42 PM11/25/13
to
Metspitzer wrote:
> On Sun, 24 Nov 2013 15:25:16 -0500, "TomR" <To...@tomrljp5.lhd> wrote:
>
>> I am trying to solve a 3-way switch circuit issue in an old house.
>> The
>> wiring in the house is old, and it is either knob and tube wiring or
>> whatever came after that and before "Romex" etc. There are no
>> ground wires
>> visible anywhere in either circuit, and everything is so dusty and
>> dirty
>> that I can't tell what is a white wire and what is a black wire etc.
>> . . . ,
>> I found the following link to various 3-way switch wiring options:
>> http://www.easy-do-it-yourself-home-improvements.com/3-way-switch-wiring-diagram.html
>> .

> http://imgur.com/mlB47zL
> I marked what should be going on. 1 (common) will be hot all the
> time. a and b will be the travelers and 2 (common) will go to the
> light.
> (BTW the color code on the ledger is wrong.) White is a traveler, not
> common.

Thanks. You're right. Where it says "White Wire (Common)", it should say
something like "White Wire, coded black (Traveler). And, it looks like they
coded the white wire black where needed to distinguish it from being a
typical neutral wire.


TomR

unread,
Nov 25, 2013, 4:21:19 PM11/25/13
to
I'll check for that, just in case that's what I have. If I do, I'll
probably post back because I don't think I'll know what to do in that case.

And, I have to admit that I was a little disappointed when I found out that
a "California 3 way" didn't have anything to do with girls in bikinis.


micky

unread,
Nov 25, 2013, 5:11:01 PM11/25/13
to
On Mon, 25 Nov 2013 11:16:56 -0500, "TomR" <To...@tomrljp5.lhd> wrote:

>micky wrote:
>> On Sun, 24 Nov 2013 17:42:26 -0600, Caulki...@work.com wrote:
>>
>>> The downfall of K+T wiring
>>> has always been that the color came off the wires, lack of a ground,
>>> and unsafe *IF* people would put oversize fuses in (which was far too
>>> common).
>>
>> I lived for 12 years in a 1930 apartment building in Brooklyn. It had
>> fuses of course, but the owner had put Fuzestat (spelling??) sockets
>> in each fuse socket, in the basement and in each of the 49 apartments.
>>
>> Blue was 15 amps, and only a 15 amp Fuzestat fuse would screw into a
>> 15-amp Fuzestat socket. The threads were at the wrong angle or too
>> narrow for other size fuses. The Fuzestat socket had raspy teeth so
>> that unscrewing one from the fuse socket it was in was hard to do.
>>
>> I think 20 amps was orange. Each apartment got 20 amps in a basement
>> fuse, and one or two 15 amp fuses in the apartment itsellf. My
>> 6-room 3-bath apartment ran on 20 amps, which was enough, even most of
>> the time with a small air conditioner. .

BTW, with Fuzestats, there is no easy way to put a penny in the socket
and bypass the fuse. Another big advantage of them. There is a
button conductor in the bottom of the hole, but there isn't the
typical side-of-the-hole conductor. Instead there are are two metal
tabs that slide along the top of the Fuzestat socket as the fuse is
screwed in, and make contact when it's all the way in. It's hard or
impossible to touch these tabs because the fuse is big enough to cover
the whole thing.

>> This all kept any idiot tenants from putting in fuses that were bigger
>> than they should be. They were more expensive, maybe a lot more,
>> than regular fuses, but worth it. In my case, the tenant paid for
>> them.

BTW, I was the tenant. I certainly paid for the fuses in my apt. but
I didn't want to wait for the super or wake him up in the middle of
the night, so even after he locked the button to go to the basement,
I bypassed the lock switch, went myself, and changed my fuse myself.


>>> If you still have fuses, by all means replace the fuse box
>>> with modern breakers. Or at least use the proper fuse. But for low
>>> amperage lighting, particularly if modern CFL or LED lights are used,
>>> there is no reason to have to rip a house apart to replace K+T
>>> wiring.
>
>Interesting info. In my case, the building has a modern circuit breaker
>panel and a lot of newer wiring with grounded 3-prong outlets etc. But,
>some of the circuits -- such as these 3-way switches -- are on the old
>wiring.

Also interesting.


bud--

unread,
Nov 26, 2013, 9:18:22 AM11/26/13
to
A "Carter" circuit. Has long been not code compliant (the screw shell of
the lamp has to connect to the neutral). I think it was once allowed
back in the K&T days. And someone might mistakenly use it. If you wire
it in any of the wrong ways it will blow a fuse.

Nate Nagel

unread,
Nov 26, 2013, 9:52:26 AM11/26/13
to
Easy way to troubleshoot:

get yourself a test light, voltmeter, or NCVD with adjustable
sensitivity, and turn the sensitivity on the NCVD down so that you can
"read" individual conductors. If using a test light or voltmeter plug
an extension cord into an outlet that's not on the same circuit as the
lights so you have a neutral available to test for voltage (I'm assuming
that you don't have a ground to use for reference, since you said there
were no obvious ground wires.)

Then, turn off the circuit for the lights, pull both 3-ways out of their
boxes, and disconnect all wires from the switches, and leave them
hanging out of the boxes and not touching anything/each other.

Turn the power back on. Check for voltage at all wires. There should
only be one wire out of all six with power on it. That's your live
feed, and should be connected to the common terminal at that switch.
The other two are obviously the travelers. Turn the power back off and
reinstall that one switch.

Turn the power back on. Go to the second switch location. There should
again be only one wire with power on it. That is one of your travelers.
Flip the first switch. Now there should be a different wire with
power on it. That's your other traveler. The wire that was never hot
throughout the procedure should be the wire that is directly connected
to the light. If you want to verify this, carefully touch it to the
traveler that's hot. The light should come on. That wire that goes
directly to the light connects to the common terminal of the second
switch. Turn the power off, make connections to the 2nd switch, turn
power back on, test, drink beer, pat self on back.

I've been in your exact situation before, and I feel your pain :) Heat
shrink and colored electrical tape is your friend when dealing with old
dirty cloth covered wiring.

Hope this helps

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

TomR

unread,
Nov 26, 2013, 3:35:57 PM11/26/13
to
Thanks Nate. That's the same process that Metspitzer suggested, and that's
what I am going to try first. Hopefully, that will work and I'll be all
set.

I thought I was going to be doing the work this week, but now it looks like
I won't get back there to do it until next week. Either way, after I try
what you and others suggested, I'll post back here how it worked out.


Nate Nagel

unread,
Nov 26, 2013, 5:40:30 PM11/26/13
to
That's correct; electricians don't always do that but any time a white
is used as a non-neutral conductor it should be relabeled with a ring of
colored tape (any color other than white, grey, or green that is.
"normal" colors for residential 120V wiring would be black or red.)
This isn't a suggestion but a code requirement.

Nate Nagel

unread,
Nov 26, 2013, 5:46:38 PM11/26/13
to
Yup, do that...

there are other options to the "normal" setup but they are rare.

What I'm expecting that you'll find is that since this is an older
house, the electrician will have run the hot wire straight to the light
fixture location, and from the same box run a 14/3 to each of the
3-ways. Back in the very old days electricity was thought of as
primarily a lighting utility and installations reflected that; a floor
was typically wired with the hot wires going to the ceiling boxes and
switch legs dropped to the wall switches from there. Receps were also
dropped from the ceiling light boxes. Wire fill would be unacceptably
high today were this a new installation.

I know what I said above sounds crazy, but that is exactly what I found
in a house built in the late 40's that I had to do some troubleshooting
on after a PO had a "handy friend" replace all the devices and none of
the 3-ways worked.

If you do find multiple hot wires with all the switches disconnected,
stop there and ask for advice as you may be dealing with something like
a California 3-way or if you're really unlucky a Carter circuit.

If your house is newer than 1930ish and/or you can determine that your
wiring is NOT K&T but actual cables (can you see the sheath of the
cables inside the boxes? I've lived in several houses that had cloth
covered wiring but they were a sort of ungrounded proto-Romex but with
cloth over rubber insulation on the wires and a cloth sheath over the
whole cable) you should not run into the Carter circuit which is good as
it would be bad news if you did. I'd be tempted to treat the discovery
of one as a sign that it is time to rewire, as it has been prohibited
for ages as in half the switch positions it allows the shell of the
socket to be energized, making removing a broken light bulb rather
dangerous.

k...@attt.bizz

unread,
Nov 27, 2013, 5:55:58 PM11/27/13
to
On Tue, 26 Nov 2013 17:40:30 -0500, Nate Nagel <njn...@roosters.net>
wrote:
I "paint" white wires that are repurposed as hots, with a red Sharpie.
I keep one in my "electrical" toolbox. I don't know if it's kosher but
it works.

william...@comcast.net

unread,
Oct 22, 2015, 5:19:49 AM10/22/15
to
My situation is a little trickier. When taking off all 6 wires, there's a hot wire at each switch. As I understand it, when the power source is between the switches, only one can be connected to the common. The way it's wired now, one switch must remain in the "on" then controlled from the second switch.

Without colored wires, the only ones I can identify are the hot wires.

Any advice?

Micky

unread,
Oct 22, 2015, 6:38:47 AM10/22/15
to
On Thu, 22 Oct 2015 02:19:42 -0700 (PDT), william...@comcast.net
wrote:

>My situation is a little trickier. When taking off all 6 wires, there's a hot wire at each switch. As I understand it, when the power source is between the switches, only one can be connected to the common. The way it's wired now, one switch must remain in the "on" then controlled from the second switch.

Wired now? I thought you had disconnected the wires.
>
>Without colored wires, the only ones I can identify are the hot wires.

First, make a drawing. Don't expect to remember what you've seen.

Turn off the power and measure the voltage at the hot wires to make
sure you turned off the right circuit.

Then measure the resistance to ground or neutral of the other wires.
The ones that go through the light bulb to neutral should have
non-infinite resistance. Do this with real lightbulbs in the
circuit. I'm not sure what the resistance of other bulbs is.

Mark down the resistance on your drawing.

The ones with infinite resistance are probably just travelers, wires
that went to the other switch, and which are disconnected now.

Get the switches, and try to figure out from the way the wires are
bent, which wires went to which screws, and try to figure out with a
meter, which screw is common and which wires are supposed to be the
travelers. With 6 wires, you should have made a drawing before you
disconnected things .

Look online for various ways to wire a 3-way switch. There are 4 or
5. Use your meter to help determine which method is yours.
>
>Any advice?

Stormin Mormon

unread,
Oct 22, 2015, 7:49:19 AM10/22/15
to
Yellow vinyl tape and magic marker allows you to
label the wires before removing. So you know where
they go. Wrap the tape around the wire and back
to itself, making a "tape flag".

Eat light meals when driving on long trips, as
over eating makes you sleepy.

Treat everyone with kindness, and manners. Even the
burglar who is in your house in the wee hours needs
to be treated kindly before you shoot his ass off
with a twelve gage and give his carcass to the dog.

Fill the fuel tank of your car before the gage gets
to half tank, and you'll be less likely to run out
of gas in a bad spot.

Wash your hands every time, after using the toilet.
Helps cut down on spread of disease. Use a paper
towel to open the public restroom door, so you don't
get the disease the last guy had. (Last guy didn't
wash his hands.)

Use salt lightly on baked foods such as chicken to
bring out the flavor.

Girls like flowers, which are cheaper than divorces.

--
.
Christopher A. Young
learn more about Jesus
. www.lds.org
.
.

Stormin Mormon

unread,
Oct 22, 2015, 7:50:47 AM10/22/15
to
On 10/22/2015 6:38 AM, Micky wrote:
> On Thu, 22 Oct 2015 02:19:42 -0700 (PDT), william...@comcast.net
> wrote:
>
>> My situation is a little trickier. When taking off all 6 wires, there's a hot wire at each switch. As I understand it, when the power source is between the switches, only one can be connected to the common. The way it's wired now, one switch must remain in the "on" then controlled from the second switch.
>
> Wired now? I thought you had disconnected the wires.
>>
>> Without colored wires, the only ones I can identify are the hot wires.
>
> First, make a drawing. Don't expect to remember what you've seen.
>
> Turn off the power and measure the voltage at the hot wires to make
> sure you turned off the right circuit.
>
> Then measure the resistance to ground or neutral of the other wires.
> The ones that go through the light bulb to neutral should have
> non-infinite resistance. Do this with real lightbulbs in the
> circuit. I'm not sure what the resistance of other bulbs is.
>
>
> Look online for various ways to wire a 3-way switch.


With both switches removed, isn't the bulb connected
to nothing on both ends?

Ken

unread,
Oct 22, 2015, 7:52:02 AM10/22/15
to
http://users.wfu.edu/matthews/courses/p230/switches.html

In addition to what you said, the above link might be helpful to William.

Micky

unread,
Oct 22, 2015, 7:52:21 AM10/22/15
to
Maybe with one or two of the ways it can be wired. I can't remember.
But certainly with some ways it's still connected to neutral.

Micky

unread,
Oct 22, 2015, 8:38:58 AM10/22/15
to
It's very helpful to me, that's for sure.

This subpage
http://users.wfu.edu/matthews/courses/p230/switches/3way/variations.html
is just the sort of page I had in mind. And it enables me to answer
the question Chris asked. Take a look and you'll see that one of the
six wires always has continuity with the neutral, if a real lighbulb,
not burned out, is in its socket. Assuming the neutral has
continuity with the ground and that there's a ground wire in the box,
that's one place to test with.

And it also reminds me of added instructions for the OP. Because I
need a drawing to think with. Is this normal, below normal or above
normal? Is it a clever way to save brain power by letting the
drawing do some of the thinking? Or would a smart person have all
this in his head without any help? I really don't know the answer to
these questions. I only have myself to compare with, and I always
match.

Keep the power off. (Always check with a voltmeter to make sure the
power is off. Sometimes there are two circuits in the same box, even
though I think this is not allowed, so one coudl be off and the other
on.)

Once you find the wire that has low resistance, under a couple 100
ohms, or a couple thousand if you can't find lower) to neutral, call
it N, temporarily connect each of the other two wires in the same box
to N. Then go to the other switch box, and check those three wires
for neutral (Well, those two probably, because you already found that
when the fuse or breaker is on, one of the wires is hot**. But if
not, then 3.) The wire that connects to neutral is one of the
travelers.

Do the same thing with the other wire at the box1 where N is. Now at
box2, you've identified both travelers, at both boxes. Reconnect the
switches accordingly.


**You claimed each box had hot wire. That's not possible if you had
really disconnected all 6 wires. But if you didn't disconnect all of
of them that's fine with me. Post back if you want instructions for
when only one switch is disconnected, or only one or two wires of one
switch. Let us know exactly what is connected, what isn't, and what
the voltages and resistances are. It's unlikely both switches are
broken but quite likely that one is.

Don Y

unread,
Oct 22, 2015, 1:37:38 PM10/22/15
to
If you have a choice between buying a new car and getting
married, buy a red one.

Stormin Mormon

unread,
Oct 22, 2015, 7:05:25 PM10/22/15
to
I once owned a red pickup. Sure felt manly.

Micky

unread,
Oct 23, 2015, 6:03:01 AM10/23/15
to
On Thu, 22 Oct 2015 19:05:43 -0400, Stormin Mormon
<cayo...@hotmail.com> wrote:

>On 10/22/2015 1:37 PM, Don Y wrote:
>> On 10/22/2015 4:49 AM, Stormin Mormon wrote:
>>>
>>> Girls like flowers, which are cheaper than divorces.
>>
>> If you have a choice between buying a new car and getting
>> married, buy a red one.
>>
>
>I once owned a red pickup. Sure felt manly.

I had a girlfriend with a red mustang convertible. Unfortunately, she
didn't have it when I knew her in NYC.

We went out once and she told me she wouldnt' go out with anymore
because I was too young. I added a year to my age and told her I was
26, thinking that would settle it. She still said I was too young.

In one of my few macho moments, I said, "Well, I'll ask you out again
and you can decide then whether you want to go out with me. " And I
did and she did.

Found out later she was 14 years older than I was, 25 and 39.

Patrick

unread,
Dec 12, 2018, 9:14:07 AM12/12/18
to
replying to Metspitzer, Patrick wrote:
Awesome. This helped me a bunch!

--
for full context, visit https://www.homeownershub.com/maintenance/3-way-switches-old-house-wiring-771957-.htm


0 new messages