I know nothing about inwall wiring and cabling, but am giving some basic guidance to a friend doing a den remodel, otherwise she would have to depend solely on her contractor. I've mostly pointed out the number/type of cables for speakers and component connections and wall plates.

I was there tonight and the contractor has already installed the blue boxes for speaker wall plates (one left and one right). BUT I noticed that they were the double wide type (i.e. double-gang J-box ) and she said the contractor was planning to use a dual face plate: one for the speaker channel and one for AC power outlet all in the same j-box. That was a surprise. I had suggested that the wall plate be just for speakers. And there would be a separate location for the power outlet.

So my question is will there be any interference/static/hum due to this AC power /speaker wire combo set up? My gut says YES, but I have no basis for this. I am not expecting the contractor to be an audio specialist but have down the basics.

This inwall speaker cabling is just for a basic stereo music system with older towers (ADS from the 90s?) and a 2 channel receiver so nothing high end here. I just want to make sure she is not going to get hum on the line. The speaker cable will be CL2 rated (it is not installed yet but the power seems to be almost wired up.) The source audio components will be on the opposite wall from the speakers, in a separate built in shelf.

The same question for the wall mount LCD but combining HDMI and AC power in the same jbox....fine or will that cause issues?

I know many of you guys do this stuff with your eyes closed and can provide the suggested method. She need to inform the contractor ASAP if they need to change the current install.

Thanks,
Ed

EDIT 01/25/09:

Resolved.....

This was discussed with the contractor, and he is revising the install to have separate boxes. His orig plan was a divider within the box.

Thanks again for all of your information, and insight!

I'm pretty sure mixing low and line voltage in the same box and/or conduit is a no-no by code.

Keep 'em separate.

Thanks Jamis
As I said I have no experience in this....I didn't even think about codes. The speaker cable is CL2 rated (monoprice). And this is in California.

Ed

See page two for this issue specifically.. but its a good read in general. :)

http://www.taunton.com/finehomebuilding/PDF/Free/021190076.pdf

Mixing the two can be done, BUT they both must have an insullation rating that is at or above the higher voltage and they both must be identified in a permanant fashion so that someone does not replace the speaker wire with the line voltage and vise versa. Good practice however is to separate the two physically by using two boxes or a separater in a double gang box.

Thanks all for the additional information! Reading it and forwarding this thread to my friend.

cheers, ed

Mixing the two can be done, BUT they both must have an insullation rating that is at or above the higher voltage and they both must be identified in a permanant fashion so that someone does not replace the speaker wire with the line voltage and vise versa. Good practice however is to separate the two physically by using two boxes or a separater in a double gang box.

DallesasseScott, In the National Electrical Code book its very specific that power voltage cables requires separate point of exit/entry [POE]. You cannot route ac and low voltage within the same junction box unless as you said using a separator, not just good practice, it's REQUIRED. Cannot run the 2 cables in the same drilled hole in a stud. They can be in the same stud bay, they can be right next to each other, however you must use a separator block in that 2 gang box.

edbayarea, I'm sure your friends electrician, if licensed in CALI will use one to separate the power and the speaker line.

Yes, DallesasseScott, the correct answer to the OP of good practice is YES, it's ok in a double gang j-box, with a separator. Wait till the guy finishes the job, he'll use a separater in the box and a wall plate that allows for proper outlet with low-voltage on the other side.

No worries, just you need to do it right to be safe.

This was discussed with the contractor, and he is revising the install to have separate boxes. His orig plan was a divider within the box.

Thanks again for all of your information, and insight!