How to pull cable using existing cable

April 25, 2008 7:02 PM

Our home builder installed cat6 network cable for me as a favor, but now that we've moved in, a cable tester now reports it as shorting out. Wires 5&6 are shorting. I guess they treated the cable too roughly. Does anyone have any advice for me on using the old cable to pull new cable through the walls to the second floor? If I was to install a messenger cable for future pulls at the same time, what should I use for that?

I figure that I would pull two cables at once to future proof myself. How would I go about attaching these two cables to the cable being replaced so that it wouldn't break in the walls? Duct tape?

I've read references in other questions here about network cabling to "messenger cables", which you could use to pull further cable in the future, which seems like a good idea. What should I get at Home Depot to act as a messenger cable?

Any general advice on how to do this without treating the cable so roughly again that it breaks? I read about data cable lubricants for pulling... is this a good idea? What would you use for that?

I think the cable may be coming through a hole between an HVAC line and the floor on the second floor, which may be the culprit for breaking the line. I bought the house while it was half built, and he had already drywalled before I asked him to pull networking cable and coax cable.

posted by Jupiter Jones to computers & internet (11 comments total)

Messenger Line is the usual term, and you can get it at home depot. Yes, you can use cable lube, but the trick is to be firm -- don't jerk the cable, pull slow and steady.

But -- by, far, the most likely place for a short is at the termination points, not in the middle of a run. The only way to know for sure without cutting a wire is to use a TDR to find where the break actually is.

What I'd do -- cut off and re-terminate both ends, then test again. You'll probably be pleasantly surprised to find that the short is right there at the jack, not in the middle of the run.
posted by eriko at 8:08 PM on April 25, 2008

I've actually already cut off and reterminated both ends twice, just to be sure. Each time the cable tester reported a short on wires 5 & 6.
posted by Jupiter Jones at 8:15 PM on April 25, 2008

Wait, you're installing gigabit networking for your inhome network? What the hell kind of data are you moving?

If just 100Mbit is enough, you know...you can just use 3 wires and treat it like cat5.
posted by TomMelee at 8:32 PM on April 25, 2008

You may find this page helpful, particularly the page concerning how to attach a piece of cable to a pull cord. Generally you use electrical tape wrapped around the join at an angle to make as smooth a transition as possible between the two cables or the cord and the cable. (And then lube it, since this is the part most likely to get stuck.)

I have heard people argue whether it is bad to pull one cable with another cable, or whether you should use the old cable to pull a cord, and then use the cord to pull the new cable. I don't think it really matters, but then again most cable-pulling I've done is in conduit, which is relatively easy compared to doing it in the walls themselves, I'd imagine. I think in some situations, it's easier to pull in one direction than the other without kinking, hence you only install new cable while pulling in that direction, and pull cord in the reverse when removing the old stuff.
posted by Kadin2048 at 8:52 PM on April 25, 2008

Oh, and if you're pulling more than one cable at a time, you basically do the same thing with the electrical tape: try to make the lead end of the new cables as smooth and tapered as possible while not making it too stiff. It may help to space the cut ends of the various cables out a bit (say 1" or so), rather than having all the ends flush with each other. That lets you avoid a hard corner that will catch as you're pulling.
posted by Kadin2048 at 8:54 PM on April 25, 2008

Re: Re-terminating...did you try re-terminating to a brand-new jack on both ends? Bad jacks are certainly within the realm of possibility and I've encountered them before on runs that were never once used until years down the road.

Re: TomMelee's suggestion...

My understanding is that cat 5 uses two pair for a total of 4 wires (and I've split a single cat5e/cat6 cable into two ethernet connections in the past). See:

How to Wire Ethernet Cables

I've referred to this document when successfully splitting cat5 in the past; sounds like wire #5 is unnecessary (for 100MBps) but #6 is required. You could get away with moving #7 or #8 into the #6 position but whatever stresses were involved in breaking #5 and #6 have probably left the cable in less-than-ideal shape.

Personally I'd still probably end up trying this because I am lazy and could not envision needing gigabit ethernet any time soon.

In a commercial setting, pulling through conduits is pretty easy and can be done with minimal stress on the new cable, especially when you can pop ceiling tiles out to help it along the way.

I've never had to do this in a home setting so I would probably use whatever tricks are at my disposal, namely lubrication and patience and perhaps a willingness to run back and forth; if you're pulling firm but seem to be quite stuck, maybe you've got to run to the other and, pull it back a few inches, and then try again.
posted by aydeejones at 5:13 AM on April 26, 2008

It appears that cat6 is 23awg and cat5 is 24awg. Cat 5 is 4 twisted pairs (8 wires) using only 3 for data transmission. Like you said, you can (if you don't mind the noise) turn 1 cat5 into two connections.

If it's your house and it's getting covered up especially, there's nothing wrong with swapping which wires you're using, so long as they're in the right spot on the connectors on both ends. I wired my house before google, and thus couldn't find the diagram---so mine's all sorts of non-standard, but it works a charm.

Moot point though---I think this feller wants his gigabit since he paid extra for it.
posted by TomMelee at 5:28 AM on April 26, 2008

What has worked for me:

- As stated above, use a cord to pull ou the old cable so that you have the cord running through your house.
- Attach cord to cable and pull.

If this doesn't work, run the cable through your HVAC vents. There might be some sort of network theory that says this is not good, but I've been using my HVAC vents as giant conduits for 5 years now and haven't run into any problems.
posted by geoff. at 8:37 AM on April 26, 2008

If you run through your HVAC, you've gotta use plenum cable to meet code. It's quite, quite expensive.
posted by TomMelee at 8:41 AM on April 26, 2008

Thanks for the advice, all!

eriko for the win! I reterminated the jack in the basement this morning after stewing over it all night.

It turns out that a big part of the problem is my incompetence. I'd never terminated ends before moving in here, and it looks like I was doing it wrong at first. I've certainly gotten a lot of practice over the last week, and I've learned to work with that tough cat6 cable.

With this new and more professionally terminated cable the short is gone according to the cable tester. I am so relieved I don't have to pull more cable to the second floor, although two lines does still sound appealing.

As for the gigabit, yeah I do transfer around some pretty large files. I've got a media server in the basement with an inordinate amount of media on it (ripping my DVDs), and I figure that if I'm going to the effort of embedding wire into the walls I may as well future proof myself and spend a little more now.

Thanks all for the great suggestions! I know I'll end up pulling speaker and AV cables around the house at some point, so this will all be tremendously useful.
posted by Jupiter Jones at 9:02 AM on April 26, 2008

Just another note from an IT guy who's fished an awful lot of cable - if it's plenum (it'd better be) the stuff is *fairly* indestructible. I'd look at bad ends, and or a faulty crimper, before worrying that the cable itself is bad.
posted by stenseng at 7:42 PM on April 26, 2008