How To/Best Way to Run Conduit (electric/audio wire) Through 2 Leaf Walls?

#1

Hello friends,

I am looking for some advice regarding my electrical service in the tracking room of my detached garage. The garage has an attic where my untreated C/R is, and my Live Room is below at ground level. I tried the search method, but to no avail.

The outer leaf of my room has a breaker box in it, so routing into the LR is will be quite easy, but the fact that I'll need an access panel for the BBox at this location (in my inner leaf) is certainly unfortunate. Besides that BBox (which has a few conduit runs through the LR outer leaf and routed back into my garage) I am designing the Live Room electrical service from scratch, which is nice.

I digress.

Besides the basics (keep AC away from audio, run electrical outlets/conduit INSIDE of the inner leaf, etc.), I am looking for guidance that will assure me I am installing it correctly, to satisfy codes of course, but mainly for superior isolation.

I visualize/speculate:

- that the shortest run of conduit is ideal.
- having a type of rubber-like wrap at the drywall entrances/holes cutout, for decoupling reasons.
- less/smaller holes in the drywall would be ideal.

That's all I have off of my mind, and I'm sure there's more to this, thus why I am reaching out. I've been trying to wrap my head around this, and similarly, how I will isolate my HVAC ins/outs, after I get the electric done, as both involve blowing holes in my hermetic seal.

Any help/guidance would be amazing. Thanks in advance!

-Chris

#2

Greetings Chris,

Search the forum for "raceways" (or "Wiremold" or "surface mount"). Legrand is the major manufacturer of the stuff. This allows you to have a SINGLE penetration into the inner leaf, then everything from that point is mounted directly on the wall. It is, however, more expensive than traditional in-the-wall wiring. I will be doing this with my build.

When making holes between your leaves, do not have them in line with one another.

For the HVAC, again, search the forum. There are a multitude of discussions on the topic, especially regarding silencers (baffles).

All the best,

Paul

#3

Great, Paul, thank you so much for a quick reply, names/terminologies are the bread and butter of most any inquiry, aren't they? 8-)

...I'll look into those that you mentioned. Also, price isn't too much of a factor, as this is certainly a yearslong project, haha.

So, just to confirm, When you say,"don't keep them in line," you simply mean to splay the two cuts/penetrations from each other (each leaf), right? At what distance does it become unnecessary to separate the holes from each other? Also, are you referring to metal conduit and/or PVC going through the holes at these junctures?...and if so, do you know what is commonly used to help seal the ins/outs of these hollow tubes w/ wires in them? It seems that would be worth doing, no?

If you happen to have a thread reference/picture to point at, that'd be appreciated, whenever you get a chance, obviously. I know it's still fairly new around here, but I at least owe it to Stuart to bring the traffic to DigiStar first, as he has helped so many people, myself included, throughout the years, it's my pleasure to follow his work.

Thanks again for helping get me going here, it's nice to meet you!

-Chris

#4

Yes, you are correct: you shouldn't be able to look one through the other. This goes for the HVAC holes too.

#5

Forgot to answer your other question. Caulk is your friend, but choose one that stays elastic for 50 years or more. There are several, but I use Big Stretch on my home remodel projects.

#6

Hi

I have several cables that need to go from outer leaf to inner leaf in my build: power and Ethernet armoured cables, fan power, lights on outside of building and power socket on outside building.

For what it’s worth, I’ve just drilled holes that are slightly bigger than each cable and then caulked both sides of the leaf once the cable is in place. I have also planned that the penetration for the inner leaf is quite some distance (in fact on a different wall) than the penetration in the outer leaf. Each cable penetrates the outer leaf in a different place than the others.

I thought this approach made more sense than cutting a larger hole for a piece of conduit or trunking with all cables in.

Good luck!
Gareth

#7

garethmetcalf wrote:Source of the post Hi

I have several cables that need to go from outer leaf to inner leaf in my build: power and Ethernet armoured cables, fan power, lights on outside of building and power socket on outside building.

For what it’s worth, I’ve just drilled holes that are slightly bigger than each cable and then caulked both sides of the leaf once the cable is in place. I have also planned that the penetration for the inner leaf is quite some distance (in fact on a different wall) than the penetration in the outer leaf. Each cable penetrates the outer leaf in a different place than the others.

I thought this approach made more sense than cutting a larger hole for a piece of conduit or trunking with all cables in.

Good luck!
Gareth

Hey Gareth,

I have considered an approach that is similar to what you described here, i.e. wires through the penetration, though I have been led to an understanding (can't remember, need a fact check, haha) that many silicones/caulks will eat away at the insulating layer of the wire sheathing over time. The staggered holes though, as Paul mentioned, brilliant.

#8

silicones/caulks will eat away at the insulating layer of the wire sheathing over time

I'm not sure this is correct: the holes made for cables (think coax here) coming into your house are usually caulked after the cable is run, and I've never seen any of those fail. If in doubt, check the label on the caulk.

#9

SoWhat wrote: I'm not sure this is correct: the holes made for cables (think coax here) coming into your house are usually caulked after the cable is run, and I've never seen any of those fail. If in doubt, check the label on the caulk.

That is a good point, though I am sure, of course, that there must be certain sealants/caulks that won't damage that layer of sheathing in specific applications such as that, i.e. Comcast/AT&T's special 'coax blend,' haha...
Again, this was a vague memory in my mind, as I've yet to find any real world science proving it to be one way or the other, but to my defense, I usually retain weird tidbits of knowledge for just cause. :roll:

It may just pertain to silicone itself, which I have used exclusively in my build, but besides the usual, "Test on small area before applying," there isn't any mention of it eating through plastic, more specifically.

Anyhow, I'm sure I'm over thinking it. Just hoping to do it right the first time.

Cheers guys, happy weekend!

#10

I just checked my caulk's instructions and it says it is good for many materials incliding plastics. I am using Mapeflex PU45 so I cannot speak about other caulks. It is worth checking.

#11

Whenever you're running conduit from leaf to leaf, you want to decouple the conduit at some point in the chain so you're not creating a flanking path from leaf to leaf. There might be a picture of this in the reference thread, but I know there are pictures of this in other peoples build threads on this forum as well as john sayers form as well. It's not difficult to do as long as you plan ahead.

#12

Jag94 wrote:Source of the post Whenever you're running conduit from leaf to leaf, you want to decouple the conduit at some point in the chain so you're not creating a flanking path from leaf to leaf. There might be a picture of this in the reference thread, but I know there are pictures of this in other peoples build threads on this forum as well as john sayers form as well. It's not difficult to do as long as you plan ahead.

Hey Jag, I've searched both forums (for pics), but have yet to find this example in practice. If you have a link/pic, that'd be appreciated.

#13

This is not the perfect photo but I can use it to explain. Imagine the two joists are the two walls. The green cable is very loose. If one of the walls is excited (as in sound excites a wall) then the cable will not transfer much if any of the sound to the other wall.

Remember the children's telephone game where with two plastic cups and a string held taut between them you can hear the other person when they speak into their cup? If the string was left floppy between the cups the noise would not get to the other cup.

Another example might be likening the cable (or cables, as we pass multiple cable through our studio walls) to guitar strings. If the strings are left all floppy the guitar would not be able to produce a resonating sound.

If the green cable in the photo was taut then some sound could transfer from one wall to the other. Try to avoid having any tautness in the cables between the walls; leave a bit of slack so that sounds cannot travel from one wall to the other, following the same principle as HVAC ducts, avoiding solid connections between the walls.

#14

An excellent explanation!

But I must know: I've never seen any cables (electrical, alarm, cable TV, etc) in that vibrant green. What on earth is being carried through that cable?

#15

I added the colour in Photoshop because I didn't want to focus on the other cables.

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