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A two-way switch puzzle

I

IaLeo

Well-known Member
Situation:a common hot wire feeds two two-way light circuits and the circuitry has worked for over ten years, but now if you switch them on, they can only be turned off (or vice versa) at the same switch, not either switch. I have tightened and inspected the feeding at the pair of switches connected to common hot, and everything looks good. I have not examined the far end switch hook ups yet, believing since both circuits "went bad" at the same time, the problem was the common feed.
I have failed the logic problem here. I know the usual two way diagram, and have not checked any continuity of the switch internals...it can't be that tough, but tougher than me! Any suggestions other than getting an professional? Leo
 
One screw is common [which is a different color] from that screw you get on / off of the other two screws when flipping the switch. Your still ahead of the game as you havent lost track of which wire goes to which screw. If you cant. figure it out replace both switches wire for wire . It is called a 3 way not 2 way. You replacing both your self is still way cheaper than an eletrician . The other [still good one s] life is near the end anyhow.
 
That is a puzzler. Couple ideas that come to mind, if they share a line they probably share the neutral. Maybe a neutral has failed somewhere? Or loose in the panel? I've seen an open or weak neutral connection cause all sorts of weirdness. Another thought is lamp type, if you recently changed out incandescent lamps for LED or CFL, there may have been some pre-existing stray voltage on the line or neutral that couldn't light the common bulb but will light the LED/CFL? Let us know what you find out.
 
The switches are Single Pole Double Throw, so like Teddy I suspect one possibility may be a bad switch. Disable and unhook the power and leads so there's no possible feedback, put a meter or continuity tester on the common Pole and observe continuity and open circuit on the Throws as the switch is flipped. PS The POLE on one switch is the hot feed and the POLE on the other wires to the light. Sometimes a bad switch fails to toggle and flip over inside even as you push it one way or the other, however, you can often hear or feel that if you know what to look for.

John T
 
(quoted from post at 13:51:55 11/20/14) Situation:a common hot wire feeds two two-way light circuits and the circuitry has worked for over ten years, but now if you switch them on, they can only be turned off (or vice versa) at the same switch, not either switch. I have tightened and inspected the feeding at the pair of switches connected to common hot, and everything looks good. I have not examined the far end switch hook ups yet, believing since both circuits "went bad" at the same time, the problem was the common feed.
I have failed the logic problem here. I know the usual two way diagram, and have not checked any continuity of the switch internals...it can't be that tough, but tougher than me! Any suggestions other than getting an professional? Leo
Click to expand...
f I read this correctly, there are 4 switches involved in the two lighting circuits (two switches each), so it sounds unlikely that two switches went bad simultaneously. Has anyone monkeyed with the wiring between working correctly & not? The switches at 'other' end do absolutely nothing? The first switches that will turn lights on/off will still do that regardless of "other" switches positions?
 
If his circuit consists of two Single Pole Double Throw Switches used to control a common light fixture so EITHER switch can turn the light ON or OFF, its wired as follows:

The POLE of switch A connects to the hot line conductor fed from the panel.

The POLE of switch B connects to the light and the Neutral wires to the light to serve as the return current conductor.

The THROWS wire together switch A to switch B

THEREFORE in my opinion (NO Warranty, may be right may be wrong) switching the light from incandescent to CFL isn't the problem, Id say there a chance a switch is bad. Of course loose or open Neutrals can cause some weird things to happen lol

HOWEVER to each their own opinion, yours is yours and mine is mine and I respect peoples views and opinions.

Best wishes

John T
 
If you replace switches, be aware that not all switches are the same - terminal for terminal. Had that happen once. Terminals did not match up. Gave me fits for a while.
 
I see now the word two is said twice?? My old brain and eyes missed the two twos lol. Still may be a bad switch somewhere in all that mix, lot easier if we were there armed with our meters huh

John T
 
(quoted from post at 14:45:37 11/20/14) I see now the word two is said twice?? My old brain and eyes missed the two twos lol. Still may be a bad switch somewhere in all that mix, lot easier if we were there armed with our meters huh

John T
Click to expand...
ust words make it difficult to 'see' what they have sometimes.
 

And to further complicate things, a brand new 2 way switch does not have the "common" terminal in the same location as the 50 year old switch that went bad.
 
There are a pair of switches outside the bedroom door, one to turn on/off the kitchen/dining area of a large room and the other switch to turn on/off
the living room circuit of this large room. If the lights are running and you turn them off on the distant switch, you have to go back to that distant switch to turn them on again. Ditto if you do that at the bedroom area switch. Which ever switch controlled the lamps last is the only on that can do it again..however either switch can do it, but they do not share the task. These are Pass and Seymour switches that worked for years as wired. No wiring has been bothered with other projects to my knowledge. Now after changing switches out with new new ones left over (I have a lot of leftovers-forty years worth :( )
there is no change and now one circuit won't work at all! Ohmmeter checking the "two way" is a puzzle too...they seem to act like one ways as I cannot find a "common" terminal that I would expect of a single pole double throw switch. WTF?
Unless I am losing it (I guess possible) this arrangement worked for years. Each switch has three terminals plus ground. No sign of arcing, melting, loose connections and the can lights they control started with R30 bulbs old style and now have cfl R30 type lamps way less amperage.
I really appreciate the willingness of this board members to help. Leo
 
[b:63bec25b08]I am not an electrician.[/b:63bec25b08]
Years ago, I had an older electrician explain how to wire these switches.
As stated, all switches are not the same. Replace switches with same brand or replace both.
Black wire terminal from one switch is hooked up to Hot (feed). Black wire terminal from other is hooked up to load (light).
Other two wires (travelers) just connect the two switches together.
And, of course, you must have neutral connected.
This was always easy for me to remember, but I may have forgotten--been a long time LOL
Some one please correct me if I am wrong.
 
(quoted from post at 14:48:13 11/20/14) There are a pair of switches outside the bedroom door, one to turn on/off the kitchen/dining area of a large room and the other switch to turn on/off
the living room circuit of this large room. If the lights are running and you turn them off on the distant switch, you have to go back to that distant switch to turn them on again. Ditto if you do that at the bedroom area switch. Which ever switch controlled the lamps last is the only on that can do it again..however either switch can do it, but they do not share the task. These are Pass and Seymour switches that worked for years as wired. No wiring has been bothered with other projects to my knowledge. Now after changing switches out with new new ones left over (I have a lot of leftovers-forty years worth :( )
there is no change and now one circuit won't work at all! Ohmmeter checking the "two way" is a puzzle too...they seem to act like one ways as I cannot find a "common" terminal that I would expect of a single pole double throw switch. WTF?
Unless I am losing it (I guess possible) this arrangement worked for years. Each switch has three terminals plus ground. No sign of arcing, melting, loose connections and the can lights they control started with R30 bulbs old style and now have cfl R30 type lamps way less amperage.
I really appreciate the willingness of this board members to help. Leo
Click to expand...

Use a very good light, and maybe a magnifying glass, and make sure that each of the switches uses the same terminal for the "common" wire. I just recently replaced one of the 2 switches that both control the same light. The old switch I took out has the "common" terminal on the top right side. The new switch has a terminal in that same position, but it is NOT the "common". Instead, the "common" terminal on the new switch is on the lower left side. I made the mistake of putting the 3 wires back in the same position on the new switch as they were on the old switch, and now I am experiencing the same thing as you. I can turn the light on with one switch, and turn it off with the other switch, but to turn it on again, I have to go back to the first switch. I spent quite some time figuring it out, but have not yet remedied the situation.
 
Leo, until you find that "common" terminal on all your switches, you are just spinning you wheels. Maybe a bulb & battery will do better than Ohmmeter. rustyfarmall probably has the problem nailed
 
After reading all the posts Leo I can tell you have a bad switch. The one closest to your bedroom. I have that vision.
 
I see "two way switch" in your post title. What the heck is that? A light controlled independently from either of two switches uses "three way" (SPDT) switches. If independently controlled by more then two switches - there are two 3-ways and the others are 4-ways (DPPT).
 
My apologies, I think of them as switches that control from two different points, but I know better and was sloppy careless about that term.
Leo
 
(quoted from post at 20:29:57 11/20/14) I see "two way switch" in your post title. What the heck is that? A light controlled independently from either of two switches uses "three way" (SPDT) switches. If independently controlled by more then two switches - there are two 3-ways and the others are 4-ways (DPPT).
Click to expand...
ep, I have always wondered about that "three way" nomenclature! Controlled from two places with switches that each have two positions. I noticed the use of "two way" but knew what he was talking about & decided not to muddy the waters with another question.
 
Those are make & break switches. When you flip one it breaks one circuit and makes the other. You need 2 switches with 3 terminals wired right, then you can add as many 4 screw switches on the travelers as you like. The 4 screw are a make & break switch too.
 
Are you saying to connect the neutral wire to the switch? 3 way switches are fairly cheap. Do it the easy and replace both of them. use the screw color (dark and light) to connect the incoming power wire to one dark terminal and on the black wire going to the light fixture to the dark terminal on the other switch. Note these 2 wires can be in the same switch box. We often did this by hooking the hot wire to the black wire in the 3 wire cable and sending it to the other end 3 way and then picking the light wire in the switch box where the power wires are. Also if using what we called a cross switch leg coming down from the light fixture the black wire in that cable MUST be the one carring the power back to the light.
 
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