3 way switch

[Greenfrog]

A room has a light controlled by a switch on each end of the room. One switch doesnt work. But,
since they are connected and 3 way, how do I isolate which one is defective? Sometimes one works
and the other not, and then again it just the opposite action. Kind of hard to explain actually.
Maybe just replace both? Hmmmmmmmm

 

[DaveBN]

I'm thinking your going to have to disconnect them one at a time and test them with an ohm meter. If you don't have the ability to do that test I would think you could take one of both switches to the hardware store and have them do the testing. I would just change both if they are the same age. Your problem could be in the wiring also, but let's hope not.
Dave

 

[wore out]

ASSUMING they used to work and are wired correctly I'd simply replace both, as even nowadays they are not a high $$$ item and if one is failing the other probably isn't far behind.

ONE of the three screws in each switch will be a different color, ABSOLUTELY do NOT lose track of which wire goes to the different-colored screw.

The new switch will work no matter how the other two wires are connected, but mess up which wire goes to the different-colored screw and you will be in for a challenge!

 

[Hemmjo]

Are you saying that sometimes one switch works. The other time the other switch works??

For discussion make one switch #1 the other #2

Flip #1 up. What happens when switch 2 is up? Then down?
Flip #1 down. Repeat #2 Up? Down?

 

[Janicholson]

Turn switch 1 up.
Turn switch 2 on and off. If it does go on and off, good
Next turn switch 1 down, then go to switch 2 and turn it on and off
If the light does not go off and on with it in one of those two tests it is the switch 1 that is bad
Doing it the opposite way tests Switch 2. Jim

 

[da.bees]

Rig a 120 volt test light with 2 leads. Expose switch wires and alternately touch leads to any two of three screws until test light and room light both glow dimly indicating failed contact inside switch. Test light at full brilliance doesn't count.

 

[Janicholson]

Good reply and simple. Jim

 

[hurleyjd]

Switches are cheap change both of them and get it over with.

 

[Stephen Newell]

You might check to see if all the wires are connected. If so if it were me I would replace the switches. The three way is convenient.

A three way switch work by having both switches wired together with traveler wires. The illustration, the switch internally will have to be connected to either both black wires or red wires to work. If one is connected to the black and the other to the red it won't complete the circuit.

 

[teddy52food]

Adding to wore out. Those off colored screws, one goes to power & the other goes to
load. Also the white wire is the return & is NOT connected to any of the switches.

 

[stoughtonfarmboy]

That sounds like the description of an incorrectly wired 3-way switch. May not be a bad switch at all. I believe another response has a diagram of the proper wiring.

Ken

 

[Hemmjo]

In regard to; Also the white wire is the return & is NOT connected to any of the switches.



This is not always true.

Depending on the location of the controlled device, the white conductor may become a switched hot wire. In which case the ends should be marked with black tape but they are often NOT marked.

HOWEVER, it is important to keep in mind depending on who wired the circuit, the colors may be switched. That is why it is important to note which conductors are on the BLACK screws.

 

[dr sportster]

Electrician would open up one switch and test contacts with his tester then replace the bad one .If you get super confused the way to trouble shoot is plug wires into an extension cord to trace the other end. Worst case scenario.

 

[rvirgil_KS]

Does not matter if these two cross.

Correct, the switch will work from either end.

However, I am a quirky guy and want both switches up or both switches down for off. Wiring one way you will get light off with both switches same direction, wiring other way will have one switch up one down when off.

 

[Dave G9N]

(quoted from post at 07:10:25 10/31/23) Does not matter if these two cross.

Correct, the switch will work from either end.

However, I am a quirky guy and want both switches up or both switches down for off. Wiring one way you will get light off with both switches same direction, wiring other way will have one switch up one down when off.

urn one of the switches around. It doesn't matter which way you install the switch. If you want the toggle on one up instead of down, you don't need to rewire, just pull it out, turn it 180 degrees and put it back in the box. There should be enough slack in the wires to do that.

The odd colored terminal should also be labelled common.



This is a decent description of the way to wire them:https://theengineeringmindset.com/three-way-switches-us-can/