3-way light switch mysteriously works, then stops working, then starts working again

Question

I have a three-way light switch that is exhibiting really odd behavior.

Sometimes it works and sometimes it does not. For example, just now the following happened.

1. Lights are off. I go to switch A and flip it back and forth. Nothing happens.

2. I then go to switch B and flip it. The lights come on.

3. I then return to switch A and flip it twice. The lights first go off, then come on again.

For about a week, neither switch was working and lights just stayed off.

It is very strange. What might be the problem here?

Note that these are dimmable lights and that there are a lot of light switches in the house so it is possible the circuit is tied into something else. Can you have a 4-way light switch?

Answer 1

CHECK

1) Turn off power for this cicuit at breaker 2) Remove switches check connections. Note: Typically, switches will have a choice of 2 different connection options:

A) Stab connection

B) Screw connection

If your switches are "stab" connected, they are more likely to become intermittent. Swap out the wiring on them to the to the "screw" connection terminals.

If they are already wired on the screw connection terminals, check tightness of connection... if that doesn't seem to correct it, change out the switches... I'd do both just because of age and / or wear.

The above is the most likely, in your described scenario.

Answer 2

Normal 3-ways are wired like this

Your first part suggests a 3-way circuit where one of the switches is miswired.

There is such a thing as 3+ switches on a 4-way circuit. Thise switches are added to the middle, and take 2 yellows on one side and 2 yellows on the other side. They either send them straight through, or swap them.

I use yellow for travelers because they are a matched pair that are interchangeable. Practical 3-way wiring with cable forces you to use 2 of the 3 available wire colors for travelers, and it can be different on every wire run. As such, I recommend removing all uncertainty by marking them with yellow tape. It makes complicated things dog simple.

Answer 3

From what you described it sounds like a switch problem. turn off the power to that light and pull both switched out of their boxes and check the connections. If the wires are just stuck in the back of the switches, backstabs, pull them out and connect them to the screws on the sides of the switches. Turn the power back on and try operating the switches, carefully, and see if you solved the problem. If so, then turn the power back off, put the switches back in the boxes and then turn the power back on. If the problem still exists then one or both of your switches are probably bad.