adding 4-way switch

[bethany14]

Hey y'all Happy New Year!

We're in the final stages of our 'facade' work! Just have porch lights to go, and then call in the city to approve us for the grant! Woohoo!

Now, to my question. We're adding (or would like to add) a 3rd switch to our foyer lighting. Two switches already exist, at the side and rear entrances to the foyer. Now we'd like to add a switch for the new front entrance, and I've bought the 4-way switch intended for the job.
All my elec work has been easy so far, b/c I'm working in walls w/out drywall! But now, I can't figure how to work out connecting the new 4-way to the 2 exisiting 3-ways. Would it be a better idea to re-wire the lighting alltogether, using the old wiring to pull in new?
I have a very basic understanding of electrical, but this is making my head hurt! Check out this for a visual aid:

Thanks for any input!
~Gayle

 

[Kerrylib]

I haven't wired them up myself, but when you sit down and really sketch it out, they aren't that difficult to understand.

Here's a link with several scenarios outlined as to how to run the connections, depending on which switch gets power and in what order the wiring is run

http://www.lightingfacts.com/Four way switches.html

Good luck

 

[Kerrylib]

Here's another web page. Looks like even better info, including troubleshooting the circuit.
http://www.electricalwiring.com/

 

[bethany14]

Thanks, but I know how it get's hooked up! Each 3-way gets looped to the new 4-way. Guess I should clarify my question. Is there a way to use the existing wiring (the wires running between the 3-ways and the closest of the two lights) or should I just use the old wiring to pull in a whole new set?
Does that make sense?

edited to add:
By the way, those are both great sites, thanks I'm thinking that re-wiring the whole thing is my best bet.

 

[Kerrylib]

After re-reading your question, I would say you should be able to run wiring from either 3-way switch or even from the light junctions out to your new 4-way switch. Assuming your existing 3-way wiring is good, I don't see a reason to re run that section.

I'm going to guess the switching circuitry goes to the light closest to the two 3-ways, so you'll have to get your new wires at least to that junction. Otherwise figure out which switch is going to be easiest to get to and pull your new wires there. If you don't already have one, one of those 4 ft flexible auger bits is really handy. You can manuever it so you don't have to open up the drywall in so many places. In fact if you plan it right, you can often go in through the openings for the outlet/switch boxes and avoid having to patch all together.

Make sure your box has enough room to accomodate the new wiring.

 

[JoeD]

All you need to do is get a 3 wire cable from either one of the existing 3ways to your new location and it can be easily wired. This will work for sure. No need to change any of the cable to the lights or switches.

It might be possible to wire from the fixture. That depends how on the circuit was wired. You would for sure need to go to the light which has the switch cables.