Finding wires behind drywall

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  #1  
Old 12-18-04, 07:57 AM
pflewis123
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Finding wires behind drywall

The guy who built my house wired the living room for speakers. He used the same kind of standard 2-strand electrical wire used for lamps and other electrical appliances to do this. I know that's not ideal, but I'm no audiophile, so I'm perfectly happy to use what he installed.

All four wires terminate at one end in a box near the stereo system. The other ends (where they will attach to the speakers) are scattered around in different locations. He just drywalled over them, and could only point out approximate locations to me.

I'm trying to find the speaker-side ends without busting a bunch of holes in the drywall and just physically locating them. Any ideas on how I might go about this?

I've checked the wires with my multimeter, and all the wires have open circuits, so I could run 110v through them, if this would help. Are there tools that would help me find them?

Thanks for any ideas.
 
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  #2  
Old 12-18-04, 08:37 AM
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Finding wires in the wall

I don't think it would be a great idea to use 110v to find the speaker wires in the wall. I suggest a less dangerous approach.
Go to Lowe's or Home Depot and get a "loaner" (return it after use) "toner and sniffer". Ideal and others make these. It consists of a little box with two alligator clip leads that generates a warbling tone on a two-wire circuit. The sniffer is a small hand-help amplifier that "hears" the warble tone when in proximity to the pair carrying the tone. Phone and data installers use these to "ring-out" or identify pairs.
The problem you might have is...the sniffer has to be in close proximity to the wire with the tone on it. It may not pick up enough signal through sheet-rock.
Unfortunately and ultimately, you may have to break out a small hole in the sheet-rock.
Another thought...
Zip cord used for lamps will work fine for speakers...but technically they should not be used in walls. Speaker wire in walls should have a CL-3 rating for flame retardancy. Of course, speaker feeds do not carry any dangerous volatge or current and they do not heat up. This CL-3 precaution is in case there is a fire in the wall that might torch up the speaker wire. There are a lot more things to worry about in life.
Hope this helps.
Bill
 
  #3  
Old 12-18-04, 09:15 AM
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I agree with Bill on using the toner. However, I also wonder whether the probe can detect the signal through drywall.

Does the wire run through an attic or crawl space? If so, perhaps you can see where it enters the walls. In that case, you could carefully measure and get pretty close to where the wires are.

Seems like next time the builder runs cable that he ought to go ahead and put the wires in a box with a blank cover. That would save a lot of for the next guy. Of course, he may have done it this way so you could decide where you wanted the box. Hope he left you plenty of wire in the walls.
 
  #4  
Old 12-18-04, 09:59 AM
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A person can really get disoriented in the attic and not know what room is below. You can use "landmarks" like ceiling lights, AC ductwork, and best of all you can tap on the ceiling from above and have someone below tell you exactly where you are. Wear a dust mask and take a flashlight. Also keep in mind that there are probably lots of cables in the attic and you have to keep careful track as you trace each cable. Measure and take notes as necessary.

Another way to do it from the attic is to follow the wires until you find where they drop into the walls. Pull the cable back up through the hole, attach a fishing weight to the end, and drop it back in the hole. The hole may be small so you have to attach something that will get through the hole or make the hole larger, or use a separate string and weight. Now jerk it around to make it bounce and hit the walls. Have someone below locate the sound and stick a post-it note at that location. Go below, find that post-it note and open a hole in the sheetrock for the outlet box. Reach in and feel around for the cable. Keep in mind that the cable can hang up on things and you may have to jerk it up and down again to get it to fall where you can reach it.

You can also put those cables exactly where you want them by pulling them back up into the attic and drilling new holes at the location you want. This assumes the cables are long enough for that.

The biggest caution is: Do not step on the ceiling sheetrock. Walk only on the wood and go slow. You do not want to have to repair a ceiling and yourself if you fall through.
 
  #5  
Old 12-18-04, 10:00 AM
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Another thought...

Once you locate your wires, as Chirkware mentioned, they might not be long enough to run to a speaker. If you have a rough idea where they are in the wall, I would cut out the sheet-rock and mount a low-voltage open back box. Home Depot has these for about a buck. They are made by Carlon (and others) They are orange to identify low-voltgage. Since they have an open back, it's real easy to pull wire through them. Then go look for a standard electrical plate made by Leviton that has two binding posts for use with speakers. Home Depot has a variety of the Leviton home telephone, audio, TV and data installation equipment. This will make a nice finished installation on the wall...and now you extend the speaker wire to any length outside the wall. If you are careful in cutting the sheet-rock out to fit the box, you won't have any spackeling work.
You might want to jump over to other discussion groups here that deal with home automation and audio stuff.
Bill
 
  #6  
Old 12-19-04, 07:12 AM
pflewis123
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Looks like I'm going to have to bust some holes after all

Thanks for all your input, folks. I tried Bill's suggestion with a toner, but apparently the signal's too weak to make it throught the sheetrock, as Bill and others were concerned about.

I also rigged a 110v circuit with a circuit finder; same result.

Good idea on the attic/crawl space; I've seen the wires running through the crawl space, but because of the configuration of the living room, the entry point could not correlate to the exit point.

And yes, I agree: it would have been much simpler to just put in some boxes or some other identifier at the time of construction - maybe a stub of some sort.

I guess I'll wait until after the holidays, since it looks like I'll be busting holes and mudding. Or maybe I'll just fish some new wires.

I appreciate your help, guys.
 
  #7  
Old 12-19-04, 10:44 AM
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Originally Posted by pflewis123
I guess I'll wait until after the holidays, since it looks like I'll be busting holes and mudding. Or maybe I'll just fish some new wires.

I'd just pull new wires rather than busting extra holes if you can access the attic and/or crawl space. You mentioned that it wasn't the exact correct wire anyway. A few $$ on wire is easier to deal with than busting holes, then patching, mudding, mudding, sanding, painting, IMO.

Good luck, and happy holidays!
 
  #8  
Old 12-21-04, 11:48 AM
ka3vvv
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Unhappy toner and sniffer

I went to work with a guy. He wasn't lic but he had a lot of work in he had two other guys working with him. I bought all my tools so I can ready for what every he was going to seen my way. He said I didn't need a toner and snuffer in some my other tools I had. He ask his two guys. What every Electricians just need. This 2-joker say just need some pliers in tape and wire nuts. You know I never work with them aging. I was trying to get a job with these guys. They never turn off power when they work. They use ther wet fingers to test the hot wire.

I know it donít have any thing to with the question but it just maid me think of that.
 
  #9  
Old 12-22-04, 07:30 AM
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Reply to KA3VVV

OM,
Great story!
Just remember, "Stupidity is the most abundant element in the world".
73's
Bill
 
  #10  
Old 12-22-04, 12:17 PM
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If the builder was smart, he left a coil of wire behing the sheetrock, to that when you cut a hole in the drywall, you can then fish the excess wire to the hole you cut. If he didn't leave alot of wire, then just fish new.
 
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