Here are the pictures, as requested: The light at the bottom of the stairs looks like There are three cables, all two conductors and the light itself. I will attempt to describe the connections. I'll call the top left cable as cable #1, the cable to its right cable #2, the bottom cable as cable #3. -white(1), white(3), and white of light wire nutted. -black(1), ***white(2)***, and black(3) wire nutted. -black(2) and black of light wire nutted. Switch #1 looks like: (I took lots of pictures, but none of them were really "easy to understand", like the fixture picture.) It looks like the bronze screw is in the middle and the adjacent screws are brass. Switch #2 looks like: It looks like the bronze screw is in the middle and the adjacent screws are brass. As far as I know, the job was professionally done. It works correctly, inasmuch as both switches can turn on the light. Given the age of the fixture, the style of the fixture, and the layers of paint, I would guess that this was the original fixture when the house was built. Does this help? I didn't do the voltmeter measurements, as I was confused by the instructions. Here are my guesses (based on other people's comments): 1) At the light fixture, the supply cable is the bottom cable. Cable #3, in my description. 2) At the light fixture, the cable going to switch #1 is the top right cable, Cable #2. 3) At the light fixture, the cable going to feed other things is the top left cable, Cable #1. 4) Normel pretty much summed it up in: "2 conductor cable is switch loop from the fixture; 3 conductor cable is between the two switches. This was my explanation way back in post #2." and "The white is not a neutral. You have the incoming hot and neutral at the light. The hot at the light is fed to the switch via the white wire, so the two wire cable is a switch loop. The screws where the two black wires attach are your commons." Texasredhead: The black wires are attached to each of the bronze screws. So, am I close in my guesses? Unfortunately, I have a followup question. I was looking at my book "Electrical code simplified house wiring guide, based on the 20th edition of the CEC and the BC admendments, 2006 to 2010" and saw this picture: In this picture, the middle switch shows the white wire going to the common terminal. Newbie/dummy question: Why is this diagram different from the way my setup is done? Am I missing something fundamental in my (mis)understanding?

The way a three way works is that power comes into the first switch on the common and leaves the second switch on that common. Either switch can be first or second. The diagram shows the power going to the farthest (right) switch, returning on the travelers to the closest (left) and from there to the light. The switches show the common on top, be very careful with that as the common could be on a single side, depending on the manufacturer. The common will be identified with a different color screw or the word common stamped into the body.

I need to clarify "#4" 4. The third line in each box represents the result of the connection. "1" = > light can be turned on/off by lower switch if upper switch is off > light can be turned on/off by upper switch if lower switch is off > light can NOT be turned OFF by lower switch if upper switch is on (light remains ON) > light can NOT be turned OFF by upper switch if lower switch is on (light remains ON)

On 3-way switches, you have two travelers and a common power line. If you look at the switch, you will see a bronze colored screw. It is important to figure which is the common as it will be the same on both switches. Usually the common is a single black wire,that is it enters the box by itself. The two travelers come into the box together and it makes no difference how they are connected to the two other screws. Pay no attention to the color of the wires. The only critical wire is the common and it must be on the bronze screw on both switches