Please help with three way switch wiring

Hi all - I'm hoping someone can help with a wiring problem I have. I did a dumb thing. I probably was a little cocky (thought I was pretty
familiar with wiring) and a little impatient (didn't label wires when I took an old fixture off). I removed a ceiling fan (wife wanted a newer one) and when I did, I just quickly undid the wire nuts (that thing was heavy!) and set about installing the new one.
Well, I was confronted with a situation I have been unable to figure out. The fan is controlled by two three way switches (they're on opposite walls in the room), and apparently only the light was controlled by the switches (fan portion operated by pull chains). The ceiling box has two cables leading into it: a three conductor (white, black, red, and ground) and a two conductor (black, white and ground). I do know that the neutrals of this setup are connected together. I get a constant 120V out of the black of the three wire cable, and depending on the switch positions, I can get 120V *between* the two black wires. Strangely enough, I get about 30V between the red and the neutrals with a DVM, a situation I'm just not familiar with. I do have a toggle dimmer as one of the switches, don't know if this could be responsible for that or not. In one of the boxes, the three way dimmer is just connected to the cable and disappears into the wall. The other box is more complicated because it is shared with three other switches. Haven't been able to trace that one out yet because I'd have to de-energize a large portion of the house, but it is entirely possible that this is where the circuit's power is tied in.
Can anyone help me figure this out and get this back together? Thanks in advance for any help you can offer.
Dave
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Dave wrote:

    Start here: http://www.wfu.edu/~matthews/courses/p230/switches.html
    Once you visualize the wiring for the 3-way switch simply insert a variable resistor into the circuit.
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Hey Ken-
Thanks for your help. I didn't think my dimmer operated as a variable resistor, but rather that it was chopping off (a variable) part of the waveform to vary the amount of power dissipated in the bulb. No matter, my DVM is probably adequately fooled, hence the 30V on the traveler (though I do have the dimmer control in the 'full on' position).
However, my problem is that I still don't know what to connect with what. I looked at your excellent diagrams on the web, and have also found some other very good diagrams showing three way switch wiring (http://www.lightingfacts.com/Ceiling%20Fan%20Wiring.html ).
In none of these diagrams is it obvious (to me, at least) where I could have a box which connects to the rest of the circuit using a two-conductor (black white ground) and three conductor (black white red ground) cable, which is what is entering the ceiling box. Is there something I'm still missing?
Thanks again for your comments.
Dave
Ken wrote:

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using a DVM on electrical as opposed to electronic work can confuse even the best of electronic engineers, i say this because all electricians would be using a "wiggy" or an old analogue meter that loads the conducters. start with fan on the black that is hot all the time and neutral. now try to find the controlled conducter from the 3 way for the light probally the red. the 2 wire is likely another unswitched or maybe switched load
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Quite a predicament };-) I remeber a call where someone had wired up a fan and left a white conductor hanging cause he didn't remember where it went :-( caused the owner some lacking functionality., I checked it with me meter and spliced it back to the wihte neutral in the box turned out is was to a receptacle. If i were there I could probably decypher it better., but let's see:
Your Blk from the 3 conductor cable is always Hot: goes to your (pull chain) Fan wire ....The White wire (Neutral) goes to your white Fan/Light Neutral.
This leaves you with a Red from your 3/W Dimmer/Switch and 2 Blk wires from the other 3/W switch, so: your Red goes to one of those Blk (rider) wires and the remaining wire to your Lamp Wire from the Fan/Light assembly.
though I don't see where the voltage between the 2 Blk wires is coming from if everything is disconnected., there are usualy 3 wires to every 3/way switch there must be a live wire at the other non dimming switch if that is the case i doesn't change the wiring scheme above.
I don't think there are any other functional options to this but test everything to your neutral conductor before splicing & capping it closed ..
Takecare
Roy ~ E.E.Technician
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anyhow i hope that works for you,
I am having a bit of second thoughts myself because I am not there seeing & testing it for myself, (wondering if you've described the remaining wire conditions 100% accurately) but i have fixed problems over the phone before with a client., saving them money & me time :-)
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I would open up both switch boxes and see how the wire is configured. If you still need help, post to the group what wire is attached to each 3way switch and which screw it is. There are 3 terminals on a 3 way and they should all be used. Typically you have a dark or brass screw and 2 lighter color metal screws. The brass screw is the common terminal and is important to know. There are many ways to hook up a 3 way $, but they all come from the same theory - 1 power source, 2 travellers, 1 switch leg and a neutral. Are you sure both whites are a neutral? If any of the 3 ways has a white wire attached to it, this white is used for power in this case.
Also, as a side note, that 30v that you measured could be induction.
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Here's some more ideas:
In the fan/light box, you need a minimum of 3 wires (grounds excluded) - neutral, hot and switched hot. Since you have 5, 2 of them will be repeats. If the travellers went through this box, then you'd have a minimum of 7 wires so you can rule them out.
If both whites are neutrals, that leaves 2 blacks and a red to understand. This also assuming the electrician didn't do something stupid and use a ground wire as a neutral.
If the 30v is induction on your red, that would indicate to me that this is the switch leg, but it should read 120v with a switch clicked the other way. Plus you say that the black of the 2 wire is the one switched. I can't figure out why the switches are controlling the 2 wire. I would think this is power in or out, but that isn't the case with how you are describing it.
Why you get 120v between blacks is another mystery? This can happen only one way: one black is shorted to ground (either by mistake or if hooked up to a load like another light or receptacle with something in it)
Is that dimmer switch a true 3 way? How many wires are attached to it and what are they? Did the light work properly before the new installation? Meaning, could you turn it on from the switch without having to make sure the dimmer is on?
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