DIY Electricians

So, I'm rewireing the house, and I've run into my first snag of many. My only holdup to running wire downstairs is a set of switches. Al the new boxes are in, and I know how I want to run the new wire, but I can't find where these switches get their power from, so I don't know where to run new wire to power the overhead lights. Here's the layout:

One ceiling fan/overhead light in the living room. It's controlled by three switches. One by the front door, one on the other side of the living room and one at the top of the stairs.
So I've got 2 three way switches and a 4 way.
How does one find where this mess gets it power from. I've put a multimeter at each of the switches and they all have legs that have 120v, but I need to find the source. To make matters more difficult the old wire is fabric covered romex, so tracking colors down isn't to feasible. I've considered doing continuity checks to figure it out, but I'de have to get 30 feet of wire to make the multimeter connections Any ideas anyone?

 

The main Power is attached to one of the Three way switches, it will be on the common screw of the switch usually marked with black on the screw.
One common wire from one three way is power the other common from the other three way is the load or fan/light in your case

The 4way switch is between the two three ways, it simply completes the circut, if you were to disconnect all four wires from the 4 way switch, your power would only be found at one of the three ways.

Here this may help:
http://www.askthebuilder.com/141_3_Way_and_4_Way_Electrical_Switches.shtml



Careful Electricity can KILL!

 

brilliant.
I was thinking along those lines, but I couldn't be sure tat would do it. The diagram that I had showed the mains coming from the light fixture, but I've only got two wires at the fixture coming out of the box, not enough to carry the mains and the switched power.
You're a lifesaver Asus.
and don't worry, I'm fully aware of the power safety issue, I'm a decent electrician, I've just never dealt with a 4 way switch.

 

so, while that seemed like a great idea it's not working out like we planned.
I've disconnected all of the wires from the 4 way switch. When I go to the 3 way switches I've got one that shows nothing, I assume it's the last in the daisy chain.
The wires in the 4 way switch box read out at 70v, as do the wires in the downstairs 3 way. I've got nothing at the ceiling fan.
I'm not sire why I'm getting a 70v reading, when it should be 120. Outlets on the same circuit read proper voltage. Any more suggestions?

 

There are old electricians...























And there are bold electricians......





























But there are no old, bold electricians.





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You have a ground wire pulled out/loose somewhere! It isn't uncommon to get a reading such as this with a disconnected ground. A reading of 40 volts or so would mean a disconnected hot wire and reading through the ground circuit.

 

Well, I've been tracking down all of the runners with a continuity tester lately, so I've gotten it all figured out.
I just needed to know what wires were travelers, and what wires went to hot, then I just ran my power to the 3 way of my choice and wired it from scratch using the existing wiring between switches. It's still old romex between switches, but it seems to be in decent shape. I'll replace it after all of the major outlet/switch rewireing is done, as that's a whole lot of plaster work to fix it.