Axiom Home Page Forums General Discussion Home Theater Proper Plasma+Speaker Power/A/V in-wall wiring

I need some help with properly wiring a new HT setup in an exisiting, finished, living room. I want to install a new wall-hanging 50" plasma and the Axiom W-series in-wall front r/l and center channel speakers. I understand that you shouldn't run ac power parallel to A/V cables or speaker cables. All of the wires will need to come from the floor/crawlspace area in this setup. For the plasma power I will be running 12ga wire through a metal flex conduit. What would be the best layout for running the power, video, and center channel speaker wire to minimize any possible interference? I'm wondering if the metal flex conduit would act like a Faraday cage and maybe it doesn't matter that the power, video and center channel speaker wire is in the same stud area. Or will I need to route the video and speaker wires through a different stud 'bay' to do this right. The attached picture is a possible layout. Does this look fine?



Also, is there a recommended minimum distance between the edge of the plasma display and the front speakers.

Thanks.
Brian

In the commercial industry where they need to run power and communication wire in a shared conduit (such as Wiremold), the conduit is usually metal with a metal divider between the signal and power wire. This seems to be enough to shield the signal cables from the power cables.

If you use a flexible metal conduit, provided it is thick enough, it would allow you to run them fairly close together. Otherwise, I'd stick with running them in separate stud spaces as you have shown.

Hi Brian,

I'm not a whiz on this kind of stuff, but I'll begin by saying that I have my power and my and A/V cables running right alongside each other in a wire loom something like this.



I know I'm breaking the rules by doing this, but I've had no problems whatsoever. No audio buzz, or hum; no video sparklies or dropout; nada. I'm not sure what I'm doing right, but I suspect that using decent quality cables is one factor (do not confuse "decent quality" with "expensive.").

Again, I'm not absolutely sure I've got this right, but I think running your power and A/V cables on a parallel course within the same stud area shouldn't cause any problems, particularly if you use reasonably good, well shielded, well made cable. If you can avoid lacing them tightly together, that would be good, but even a few inches apart should suffice.

Now, if someone comes along who has more knowledge about this than I, and tells you I'm a damned fool, by all means, listen to them.

Hey Bruce,
I'd certainly would prefer to run the metal flex in the same stud space since it will simplify the amount of drywalling I have to re-do. I was planning to use standard 1/2" metal flex. Do you think that this would be 'thick enough' to keep the power and video in the same stud space? What thickness would be adequate do you think? Buying thick-walled metal flex is cheap compared to the work involved with re-do more drywall . If I keep them in the same stud space they would be separated by about 14-inches, of course.
Thanks.
Brian

OK, first off, I know I'll get piled on by those who are concerned about "code violations". No biggie, I understand the consequences...

Below is a pick of how I did mine, cheap and dirty. My cable run doesn't have audio, just power and video (composite, component, DVI, and VGA). I don't see any degradation in PQ because of the AC being run w/ the vid cables, no conduit either. I did have to run the cables a little lower than desired because of the horizontal stud at about 4'.

For power, I would run an outlet behind the plasma. Why? because you might decide to run ambient lighting as well, like an Ideal-Lume, and it'd be nice to already have an outlet there. I didn't run a extra power cable and I kinda regret it. The spacing is tight and it'd be hard for me to redo the cables.

I was certainly going to put a power outlet behind the plasma just for the case you indicated. BTW, what brand of mount are you using?

Omnimount, about $150 at Circuit City.

Brian,

Like Oldskoolboarder, my wire and cable runs have always been cheap and dirty. In fact, erring on the side of caution, I usually suggest that cables should not be bundled together because of the theoretical danger of induced interference.

However, usually an inch or so of physical separation between AC power cords, video cables and speaker cable is sufficient to remove any danger of induced effects (because of the inverse square ratio law, too tedious to go into here).

Anyway, I've never encountered any kind of induced hum or video anomalies in the many decades of running cables to A/V gear.

The "ground-loop" monster is the only occasional problem that crops up. That, and once living within one city block of a TV transmitter of a station where I once worked. In the latter case, my speaker cables served as a primitive antenna, feeding the audio of the TV signal back into my amplifier where it was rectified and showed up in the background no matter what source I listened to. Replacing the standard speaker cables with shielded speaker cables fixed the problem of the Radio Frequency Interference (RFI).

Regards,

The Wiremold product I would estimate at about 16 gauge for the metal separator. However, as others have suggested, good quality cables can eliminate any interference.

As an extreme example, I had one studio audio installer describe to me an unshielded twisted pair cable that was developed in Japan. It had a special relationship of the twists (not a constant twist) that allowed the installer to run the signal cable over long distances and right over fluorescent lighting with no interference to the signal.
I don't remember the cost but the point is that if your cables are well constructed, running them within the same stud space and on opposite sides should work with no problem. The metal flex-conduit is added insurance.

Thanks. It looks like I'll go with the flex (power) and good a/v cables in the opposite ends of the same stud bay.
Brian