Another 3 way Mess

JPM · 02-11-2009, 02:02 PM

I had fun reading the other 3 way mess ... glad I am not alone.

Here is my situation...

Just bought an old property that needs work. The prior owner had started to do some electrical work on a stairway with two lights (top and bottom) controlled by two three way switches.

When I put in new bulbs, I got no light, so I opened the switch boxes and found a mess. I had to snake a new feeder up from the basement to replace the cut one I found.

The rest of the wiring is old but appears in good shape. My issue is how to figure out how to wire the second switch. The wires are not color coded (old type with black and cloth wrap) so it is difficult to trace.

What I get right now is that I can use the first switch (box with the feeder line) and get both lights to turn off and on. I guessed at wiring up the second switch but guessed wrong. Right now, when I flip it, nothing happens...the lights do not go on or off. Also, there is a 2 wire cable going into the first box that was not terminated on either wire .. wondering if it was somehow part of the circuit? Anway,

Do I have a traveling wire switched with the switch-to-light wire on the second switch? Or is it something else?

Thanking everyone in advance as I have had nothing but good advice from this site!!

220/221 · 02-11-2009, 02:14 PM

AllI can do is tell you how the system works.

There are a dozen ways to accomplish it.

The 120v hot goes to the common terminal of one switch.

The hot wire going to the lights (the switch leg) go on the common terminal of the other switch.

Two traveler wires go from switch to switch, connecting the other two terminals.

Neutral wires are connected in a path back to the panel.

Yoyizit · 02-11-2009, 02:57 PM

It is just a series circuit made up of a source, a load, and a composite switch made up of two switches. It still just turns a light on and off.

Pick a 3 way schematic and a wiring diagram that allows you to most closely follow the existing wire schematic, routing and colors. There are three wiring diagrams that I know of; the light at either end of the chain, or in the middle.

Ignore wires that are just passing power onto other circuits, assuming you can figure out which wires these are. This involves figuring out which way the power is flowing and this is not as easily done as with DC circuits.

With some of these setups, worked on by who knows who in the past, it may be possible that it is not possible to salvage what is there, but you don't dare start randomly disconnecting wires, either.

I'd do what I can with the power off, an ohmmeter, and an extension cord to bring the ohmmeter leads to where you need them, but first draw what you see in each box so at least you can return the setup to the previous state, imperfect as it may have been.
To use the ohmmeter you need to disconnect wires and unscrew the bulb.

Wait till you try to debug 3 or more switches controlling the same light!

rgsgww · 02-11-2009, 02:59 PM

Diagram...Light is on...

Yoyizit · 02-11-2009, 03:09 PM

As Mr. 221 said, there are exactly 12 combinations/permutations of a light, a source, and 3 places they can be, with the switches being with the source or not. I'm assuming a 3-way switch is never placed at a light.

Lift up roof, insert new house, lower roof.

joed · 02-11-2009, 03:47 PM

You have just barely started to giving the info needed to attempt to fix this.
You have feed going into lower switch.

Where do any other cables from the lower go?
How many wires and where do they go from the upper switch?
How many cables, with how many wires are at the lights? Where do they go?
Is there any knob and tube wiring or is this all cables?