In-wall low voltage wiring questions (1 Viewer)

[jaidog]

I am in the process of converting a den into a home theater.
All walls have existing drywall. Three of the walls
are filled with insulation -- two of these are filled with
rolls of insulation, the other with blown-in insulation.

I plan to run metal conduit from various wall locations
to the basement below. I will run speaker cable and
subwoofer cables through this conduit. Locations include
front, left, right, center, and rear speakers. Other
locations include three potential spots for a subwoofer.
I want to have some flexibility with subwoofer placement.

Is 1/2" metal conduit sufficient for what I want to do?
What should I use at the terminating side of the
conduit? I could use a metal junction box, but it seems
overkill for low-voltage wiring. Are there better
alternatives? I would like to purchase everything
at a home center (ie Home Depot) rather than online,
with the exception of cables which I will purchase
from monoprice.

 

[Robert_J]

Plastic conduit is cheaper I think and available at Lowes or HD. How long are the conduit runs? From the wall plate down to the basement? If they are that short, I wouldn't even bother. Just run the cable through the insulation.

Don't forget that Lowes and HD have bulk cable. I'm using RG-6 for audio, video and sub cables in my wall and attic.

-Robert

 

[jaidog]

The conduit runs will only be three to four feet. But, I want to run
conduit rather than cable so I can change cable in the future, if needed.
Seems like it would be easier to run the new cable through the conduit
vs. fishing it behind a wall that is filled with insulation.

Just not sure what alternatives exist for the box behind the wall
plate. Like I said, I could use an electrical box, but it seems like
overkill.

As far as cable, I've used RG-6 for a subwoofer cable in the past,
but crimping was a pain and the connector on each end is not
as secure as other pre-made subwoofer cables seem to be.
Monoprice has 35' subwoofer cable for $9. I think it is RG-6 with
decent connectors at each end.

 

[Leo Kerr]

there are various plastic boxes suitable for what you're doing, too. The blue plastic boxes are good for line or low-voltage. There are much smaller, generally orange boxes, that are specifically for low-voltage/signal wiring.

Some of them aren't so much "boxes," but something more "to hang a face-plate on."

Leo

 

[jaidog]

Leo,

The "to hang a face-plate on" type boxes seem like they would work perfectly. I haven't seen these at either Home Depot or Lowes. Do you know where I
could purchase them without shopping online?

 

[Robert_J]

Walk through the electrical section at Lowes and just look at the different options.

I have insulation in my theater walls and no conduit. I ran a few nylon strings (the pink, construction style) between the wall plates and the attic. When I want to run new cable, I just tape it to the string and pull.

-Robert

 

[melbeach]

Right here: Home Depot Search. Look at the "old work" boxes to install in existing drywall.

I would have just gone with the hollow orange one, but it didn't work with my faceplates. When I installed the faceplate, it left a gap between the faceplate and wall - about 1 mm. The blue ones compensate for that, with an indent of about 1 mm at the screw holes. You'll want to test this with the faceplates you have.

 

[melbeach]

Wouldn't the cable bend while you're trying to pull it thru? If you tape the string to the end of one of the cables, then pull from the attic 6 ft away, it seems like it would loop around on you and you'd be pulling the cable straight from the end. It seems like you would need the conduit to keep it straight. That was my reasoning for using conduit. Does it not work that way in real practice?

 

[Robert_J]

I'm not sure I follow you so I'll describe my process.

1. I make sure I have at least 12 feet of string exiting the hole in the wall. It travels up into the attic and is tied to a board.
2. At the 10 ft mark on the string, I tie a knot. It keeps the electrical tape from sliding down the string.
3. I tape a piece of coaxial cable right above the knot from step 2. Two or three very tight wraps of electrical tape are enough to hold it.
4. I position the carboard box holding the cable so that it will feed directly into the wall.
5. I go into the attic and pull the string up. It drags the cable up the interior of the wall.
6. As soon as I see the end of the cable, I cut it free from the string and pull as much as I need to reach my destination.
7. If it is another room, I do this process in reverse with me pulling the another string from inside the room.

If the cable is not easily fed into the wall, I get my wife to help by feeding the cable as I pull. And you are wondering why I used 12 feet of string? I pull 10 feet up inside the wall. That leaves me with 2 feet sticking out of the wall. I can run downstairs and pull the string out and run a second cable. Normally, I'm running multiple runs from the same box of bulk cable so I have to repeat until I have everything run.

-Robert

 

[melbeach]

Okay, that makes sense for pulling a new cable up. I was only thinking about pulling an old cable out. If that's all you were doing, it seems that the end of the cable would bend around while you were pulling it up. But now that I think about it more, if you had a new cable taped to the end of the old cable, that would keep it from bending.

 

[jaidog]

Thanks for all of the excellent advice. I went to Lowes and found that
they now carry low-voltage brackets. In fact, they have two brands,
one of them being Carlon. Can't recall the other one. These are plastic
brackets without backs and they come in two varieties -- one made for
new construction and one made for existing work. I also saw metal
electrical box mudrings that were less expensive which I plan to use
in some locations.

So, for my one wall that is not drywalled, I plan to use the mudrings and
attach to studs. I will most likely use string, as suggested, from these
mudrings to my basement.

For the walls with drywall and insulation behind the drywall, I plan to
use the existing work low-voltage brackets and string.

For the one wall with drywall and no insulation, I plan to remove some
drywall and use new construction low-voltage brackets or mudrings
depending on whether I have a stud to attach to. This is where
all my components will be located so I plan to run a flexible plastic tube
to the basement, and another one to the attic. The basement tube
will be for 5 speaker cables and a subwoofer cable. The attic tube will
be for an HDMI and other cables necessary for the projector. Due to
the flexible plastic tube, I anticipate that I will need to tear out a
chunk of this drywall.

Thanks again for all the advice. It helped that I knew what I was
looking for when I walked into Lowes.