I moved into a new house (new for us, not brand new). I am in the process of replacing outlets and some light fixtures. One issue that has me stumped is we have a switch at bottom of stairs and two up that control hallway light up. If down has been used sometimes lights cant be turned back on with switches up. Where should I start? Is this a case that i have 3 three way switches and one should be a 4th or sound more like they are just mis wired? Any suggestions would be great. Thanks.

 

Two 3 ways are used if something is controlled from 2 locations. Four ways are used when there more than 2 switches in addition to the 2 3 ways.

Sounds like a common is transposed with a traveler.

 

Thanks, what is best way to find/troubleshoot?

 

First identify which two switches are three ways. Those will be the ones with only three terminals and maybe a ground screw. Tell us how many 3-conductor cables (red, black, white) and how many 2-conductor cables (black, white) and how they are wired. Do you have a a multimeter? (A non contact tester won't do the job.) We will also need to know the wiring at the light.

 

I'm not sure whether we'll need to know the wiring at the light(s), at least for starters. Tell us about each switch for now, and let's see where we can go from there.

 

Thanks, i appreciate the quick responses. Once i get a chance to take a look (may not be until the weekend) i will let you guys know, this is very helpful.

 

Guys,

I finally had time to get back to this project. The switches are as follows:

Bottom of stairs: three wires: black, red and white

Up top stairs: three wires: 2 black, one red (also some white in box in screw caps)

Up stairs hall: four wires, 2 black, 2 red

What can i check next. Thx.

John

 

Those are your two 3-way switches.

That's a 4-way switch.

Each of your 3-way switches has one common terminal and two traveler terminals. Often, the common terminal is differentiated with a black screw while the traveler terminals have brass screws.

It appears that the switching for your upstairs hallway light may just not be connected properly. Let's assume for the moment that the 4-way switch is wired correctly. (There should be two white wires spliced together behind it, BTW.)

Tell us which wire is connected to the common terminal on each 3-way switch. Also, drop the light fixture. Don't take any wires apart there yet - just tell us about the cables and wires you find there.

 

The ceiling fixture has a white and black wire. The downstairs 3 way has a red on the dark screw (black and a white on the other two) the upstairs has a black on the dark screw (black and a red on the other two). Thanks.

 

I switched some of the wires trial and error on the three ways and cant seem to fix it, what should i try next?

 

One of those three places should have a two conductor cable that is always hot in addition to the cables mentioned. If there is only a single two conductor cable at the light then the most likely scenario is both a two conductor cable and a three conductor cable at each three way switch. If not describe in detail all cables and their wires at the four way switch.

 

All set, thanks guys. One last attempt of switching one more wire on the second 3 pole did the trick. Appreciate the help.

 

On that downstairs switch, remove the white wire. Move the red wire to the brass screw where it was. Mark the white wire with a bit of black or red electrical tape or permanent marker near the end. Connect it to the dark screw. Mount and cover that switch. Leave the other two switches as they are for right now.

We'll get to those. First, though, we need to know about each cable, and each wire in each cable, in the ceiling box for the fixture.