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I want to install an ethernet jack in an interior wall of one room. I'd like to run the cable up through the wall cavity (so it is hidden) into the crawl space and back down another wall to another jack which would be connected to the network router. I presume this is a pretty basic thing to do but I'm not sure how to access the wall cavity. The walls are covered by a horizontal beam that gives me no clue what is underneath or how high they are.

Should I drill down at the red X(see picture) and feed the cable through, then guess the right spot to drill a hole at the site of proposed jack (coloured green)?

Diagram of problem

NB: I have been reading this question but it doesn't quite answer mine: How do I run ethernet, speaker wire, and coax through a wall into a crawlspace?

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Make sure you pull some extra cables. Two Cat5's can even carry HDMI. Or at least run conduit as needed to make hard parts easy. –  Jay Bazuzi Jun 29 '11 at 2:40
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When you say "run conduit" what kind of conduit do you mean? Wikipedia mentions 14 kinds, admittedly only some of these relevant to private dwelling scenario. en.wikipedia.org/wiki/Electrical_conduit#Types_of_conduit –  Lisa Jun 30 '11 at 5:08
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7 Answers 7

up vote 6 down vote accepted

To help you with the terms, what you're looking at from above is the top plate. Frequently there are two 2x4's for a top plate. Two boards are used for added structure at the joints and extra fire proofing. This gives you about 3" of wood to drill through.

As ChrisF mentions, you should run a stud finder up and down the wall cavity near the halfway point to see if any fire blocking has been installed. This would be a single 2x4, and will almost always be in a wall if the ceilings are over 8' tall.

You'll significantly reduce the odds of insulation in the wall if you are doing this project on interior walls. You should also be avoiding any electrical in the same wall cavity (between the same two studs). You would see an outlet, switch, or wire coming out of the top plate if this were the case.

As for the actual wiring, I've used these low voltage mounting brackets for the hole in the wall. Place the bracket on the wall where you want the opening, mark the corners and sides, and cut out the drywall with a drywall saw. Test fit the bracket and file back any spots that are blocking you until you get a snug fit. Then bend the tabs back into the wall and tighten them with a pair of pliers. On that bracket, I use a modular plate (these comes with more openings if you need them) and then an ethernet jack mounted in the plate. You can also get jacks for cable, phone, stereo, etc.

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I agree in general. I would recommend the use of an old-work J-box instead of a plate mounting bracket, especially if it turns out the wall is insulated. Yes, it's low-voltage, but the J-box helps protect the delicate back-wiring for connections like Cat-5, much like it does for high-voltage lines. –  KeithS Jun 28 '11 at 14:33
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If it's insulated, fishing the wires down the wall will be a pain. Better off installing in another wall if possible. With the exception of walls bordering the outside or noisy areas (bathroom drain pipes) most walls inside the home are not insulated. –  BMitch Jun 28 '11 at 15:53
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And if your collection of cables going to the wall plate includes coax (I was running phone, coax, and ethernet to every room) you'll like the extra flexibility of a backless bracket. –  BMitch Jun 28 '11 at 15:56
    
@KeithS @B Mitch: These guys offer minor protection to the connections, while also allowing less flexible cable to enter the "box" easily (The best of both world). –  Tester101 Jun 29 '11 at 14:32
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@Tester101, those are good for new work. You'll need another version for old work. –  BMitch Jun 29 '11 at 14:46
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As others have mentioned, there may or may not be stuff in the wall obstructing your plan. But most likely not (insulation it the most likely, but should not stop you). Find an area between the studs and cut a hole in the wall where your box will go as other have described. Then drill a 3/4" - 1" hole in top plate within the same stud cavity. That's the easy part.

To actually fish the wire (up or down), you really should get steel fish tape. I spent so many years fishing wire without this, and once I discovered them, I realized I could have saved so much time. It is a steel wire that rolls up but does not bend left to right, so you can put it up or down the cavity (down would probably be easier as you can stick your hand in the hole too grab it). One you have it pulled through, attach your wire to the end, and pull it back up. Believe, this will well worth the $7.99 you will spend.

enter image description here

I have also used a contraption that gets attached to the fish tape that is like those old Chinese finger traps you probably played with as a kid. It's a wire mesh that you put you wire in, and then locks on to your fish tape. As you pull, it gets tighter on the wire so it will not disconnect in the wall. Before I had one of these, sometimes the wire would disconnect from the fish tape in the wall and you would have to start over. I could not find a link for this, but it is sold in the big box stores right by the steel fish tape in the electrical section.

Good luck!

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Notice that this fish tape has a hook on the end. That's important. Mine doesn't have that hook, which is annoying. In difficult situations, you can use two fish tapes - one from each end - and get them to hook each other. –  Jay Bazuzi Jun 29 '11 at 2:37
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If you feed the cable from the crawlspace, you will probably not need a fish tape (assuming there is no insulation). gravity will do most of the work, the hole in the wall (where the box will go) should be large enough to grab the cable without a problem. –  Tester101 Jun 29 '11 at 14:26
    
Thanks for advice so far. I take from this that the pale brown thing in my picture is called the top plate. My concern is about where I drill down through that and how thick I should expect the top plate to be. Or perhaps this is trivial. –  Lisa Jun 30 '11 at 4:41
    
Yes, that is the top plate. B Mitch's answer describes the thickness, either 1.5" or 3" is most likely. As for where to drill, use a stud finder to locate the 2 studs on either side of the proposed location. Drilling your hole anywhere in between will be fine. –  mohlsen Jun 30 '11 at 12:14
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You already have an accepted answer on how to achieve your result, the only note I would make in addition is that if you want to use gigabit connections down the road ( most computers now are on the 10/100 mbps standard, which cat 5/5e is fine for ) you should run cat 6 cable. It generally costs a small amount more, but is easier than re-fishing a wire down the road.

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Ta. Definitely sensible advice. –  Lisa Jul 1 '11 at 4:36
    
Category 5 or 5e cable is fine for gigabit according to wikipedia: en.wikipedia.org/wiki/1000BASE-T#1000BASE-T –  tomfanning Mar 14 '12 at 7:23
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One thing I've learned over the years is that cutting and repairing drywall is sometimes easier than the aggravation of trying to run wires through a wall. If you think there is blocking up the wall as ChrisF said or insulation, it may be easier to cut out a section of drywall that gives you the space you need to run the wire then repair the drywall.

If you don't want to do drywall work and have few obstructions, You can follow the directions in the other post you mentioned. Cut out the location for your ethernet box, find a reference point and measure, then go into the crawl space and, using your reference measurement, drill a hole through the top plate. If you're off, no big deal, just move the appropriate distance and try another. Run some fish tape from the top with a hook on the end, then run another, or something else with a hook, from your box location up and hook the top tape. Pull the tape out of the box, attach the wire and pull the wire up into the crawl space. Seal the holes with foam.

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Another benefit of opening up the wall is that you can install conduit (for any future cable runs). –  Tester101 Jun 28 '11 at 15:55
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The biggest problem with drywall repair for DIYers is the Sunday Dinner deadline. Drywall is really a 3 day job, meaning it's not appropriate for a weekender like myself. –  Chris Cudmore Jun 28 '11 at 17:18
    
@chris - Well, there's that...and the dust. My wife hates the dust. –  billoreid Jun 28 '11 at 17:33
    
Thanks, really useful. But is the foam strictly necessary? What are the disadvantages of not using this? –  Lisa Jun 30 '11 at 4:56
    
Not totally necessary. I read crawlspace and assumed "open to the outside world." If it's inside, like an attic, and there's insulation covering the hole, I myself would skip the foam. –  billoreid Jun 30 '11 at 11:56
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I used to run ethernet cables all over the house... I would star them from a central location where I had adequate ventilation / power for my devices... then I realized that the (Cat5e) results I got didn't justify the time and pain of fishing things around tight areas in the house (attracting sweaty globs of insulation all over my body)...

I have been using HomePlug AV to replace physical ethernet wires with very good success. As long as your power circuits between your endpoints meet the basic requirements1, you should see between 30 - 70Mbps through your power circuits using HomePlug AV 2. The devices I use are made by NetGear, but you could choose pretty much any one that you feel comfortable with; I read reviews on Newegg to filter products like this.

Your total cost out the door to start with a single HomePlugAV connection is about $100; that buys you a pair of the transceivers (equivalent of running one wire). Afterwards, you can incrementally expand in multipoint ethernet fashion on the same electrical phase by buying one more HomePlugAV transceiver for about $50/ea.

A single transceiver looks like this (front / side views)...

HomePlug AV transceiver

EDIT

In response to Lisa's comment, I will add this bit about my experiences with Homeplug AV...

I have been using Homeplug AV ever since the first commercial implementation shipped on the Zyxel PLA-400 (v1) in 2007. I started using Homeplug AV because I was getting frustrated with 802.11g and unreliable connections; this was in a residential neighborhood and I was only 60 feet from the wifi source (WRT54GL running at max signal strength). As a network engineer, I have very high expectations for reliability, and HomeplugAV has not disappointed at all. I routinely keep ssh and VNC sessions up for months through HomeplugAV links3. The technology uses Forward Error Correction with OFDM, and my apps are all TCP... I have never had a reliability issue, even when the washing machine, vacuum cleaner, or power tools operate on the same AC circuit4. That said, I have never streamed UDP video through this, and that truly would be a different use case.


End-Notes:

  1. The issue that stands the biggest chance of being a problem is if you want to transmit a single HomePlug AV connection across two different electrical phases in the house. If you need to bridge the electrical phases with HomePlug AV, use an ethernet switch fed by HomeplugAV transceivers connected to the two phases. Also be sure you do not plug a HomePlug AV device into a UPS or surge protector... they are only designed to go on basic electrical wall outlets.

  2. Don't believe numbers larger than 70Mbs for HomePlug AV... there is a lot of unusable-bit-count marketing involved in most of the Homplug AV products.

  3. In four years of use, I can only remember dropping one TCP session across Homeplug AV, every other time TCP sockets are manually terminated by me (since there was only one drop I am not 100% sure this can be blamed on HomeplugAV). I immediately restarted the session, and have not had another problem.

  4. Initially I used it through 2-wire romex laid in the 1950s; after I sold that house, I used it in an apartment complex with similarly stellar results (using Netgear transceivers, as my original Zyxel PLA-400 croaked after about 3-years). While some might gripe about replacing the transceiver after three years, I am (so far) not concerned; that Zyxel was literally one of the first units they shipped. I ordered it off NewEgg as soon as they released it.

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Thanks for this. I considered this option but rejected it partly because I don't understand how it affects or is affected by noise from electrical appliances or anything else connected to the same wiring. And seems over-complicated for what I want to achieve. That said, I acknowledge this will be the future solution to network cabling when mature. –  Lisa Jun 30 '11 at 5:00
    
Thank you. You're starting to convince me. My partner was really keen on this approach when I mentioned it too. –  Lisa Jul 1 '11 at 4:34
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+1 I too found power line networking to be a great solution instead of trying to run ethernet through an existing house. One of the problems I faced with trying to run ethernet was that most of the walls I wanted to go through were insulated or I would have to run down 2 stories, which made it practically impossible. I have 4 powerline networking interfaces now and am really happy with their reliability and speed. –  deltaray Jul 5 '11 at 4:03
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You can use fish tape to help run the wire. I have a friend that is wicked good at that. I have never tried. I have always just removed trim and baseboards to run the wire from room to room. I cut a groove in the back of the pieces with a router or a table saw with a dado blade.

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I've used fish tape many times. It might take 2 people but it will work. –  Joe Philllips Jun 28 '11 at 16:02
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Theoretically this should work, however there could be other cross pieces in the framework that would block your path to the location of the socket.

You would need to get a drill bit that could reach all the way down.

There could also be insulation in the cavity that would block your path too.

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Thanks. How long do you think the drill bit would likely need to be? I have a 9mm timber drill bit which could go through 100mm or more. The house is in Australia and was built in 2004 so all modern. –  Lisa Jun 30 '11 at 4:45
    
@Lisa - 9mm might be OK. Drill a hole in a test piece of wood to see if you can feed the cable through that easily. –  ChrisF Jun 30 '11 at 7:46
    
Note for Australia: it is ILLEGAL to run ethernet in walls or ceiling spaces. You need to hire a licensed structured cabler. –  LegalEagle Feb 19 at 2:38
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