Pulling cable through 10m conduit

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greaneyr

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#289090 11-Aug-2021 20:02

Hi all

I'm currently in the process of extending my home network out to my garage. It's a detached building, but there is a conduit running between it and the house, containing (now) a single strand of black external grade phone cable. It used to contain two cables, but I have removed one in order to free up some room in the conduit for the pull.

Despite a fair amount of video-watching and preparation, I'm still not sure of a failsafe way to complete this work. I'm mindful that, if I screw up this current cable, the conduit will be empty and I'll have to break walls to get to the other side of it if I want to blow a new pull string through. There's also the added problem that it needs to get from one side of the conduit up near the roof of the garage in the wall cavity. At the moment, because everything is still joined, this isn't a problem. But if the cable breaks for any reason, that portion of the run could be somewhat challenging to re-instate.

The cable I removed was the shorter of the two. I tried tying a pull string onto it and taping tightly around it, but even this was too tight to fit through the entrance (the pipe is I think 15mm, and with a second cable already in there, it was just a no-go). So I figured I would remove it, and keep the other cable (which is about twice as long as the actual conduit is) as my eventual pull string.

The cable that's still in place has a join on it on the house side - all four wires have been spliced using connectors, which means I will need to fit that through the pipe (unless I pull from the other side of course). I have bought some wire pulling lube. I'd like to be able to lube up the entirety of the run, so am thinking I probably want to swap the cable that's in there with a decent length of string.

My fear is having the same thing happen as before, but inside the duct, rather than at the entrance.

I can think of two options:

1) Pull the longer side through, and attach a string somehow, so it's as narrow as possible. This has the advantage of being able to (theoretically) be pulled back in the other direction if it gets stuck, and even after the full length of the pull string is in the pipe. The only problem is it means the joined section will need to be pulled right through. I have no idea how viable this is. The join looks reasonably narrow, but then so did my attempt to tie and tape the string onto the cable, and that wouldn't fit.

2) Pull the shorter side through, along with the string as above. This should come through cleanly, since there's no obstructions on the tail end (other than whatever I use to attach the string). The problem is I lose the advantage of having a sturdy and thick cable in the pipe, because once it's out that's it. The string will be my only hope. I could add more pull strings if I wanted, I guess.

The cable I'm running through is external grade cat 5e, which is slightly wider than the existing cable.

Which option should I opt for (or another if there's a better approach)?

Thanks

Richard

andrewNZ

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#2758761 11-Aug-2021 20:25

I'd pull a draw wire/rope (you want something good and strong and at least twice as long as the conduit) through from the short end. Mainly because there *SHOULD* be much less chance of losing it, because the conduit is unrestricted.

The main trick is tying that rope on so it isn't going to come off. My main tip here is, use good insulation tape like 3m or nitto, and stretch it when you're wrapping it. Stretching it ensures it pulls in tight. If you don't stretch it, you may as well just use sellotape.

Once you have the rope in, don't pull it out, tie your cables onto the middle when you're pulling it them in.

greaneyr

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#2758772 11-Aug-2021 20:59

Ahhhh. Genius (the whole 'rope twice as long' thing I mean). I'd never thought about attaching the new cable halfway, but that removes most of the risk from the second stage at least (provided the rope is good quality).

Do you have any recommendations on what string/rope to use? Also, when taping it to the cable (initially) do I need to tie it as well as tape it, or is the aim to just do a good enough job of taping (by pulling tightly) so I don't have to worry about knots adding width?

SATTV

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#2758783 11-Aug-2021 22:02

You could try some fishing nylon, 80 - 100 lb is strong, flexible and cheap.

As for joining it I would use a series of slip knots, practice on some of the cable you pulled and something solid so you know your knots are good. Fishing braid would be better, stronger, less stretch and thinner. ( the best knot to use is called a FG Knot but it is not an easy knot to ties for the first 100 times or so )

Just remember when you you hit a snag, dont force it, pull back the other way a little and try again.

Best of luck.

John

I know enough to be dangerous

MickeyD

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#2758788 11-Aug-2021 22:17

I've used the 3mm nylon (CJ630) from here to pull some fairly long runs of cable.

The trick was to get the pull cord through the conduit first, by tying a bit of plastic bag or gladwrap to one end of the nylon, tuck it in the pipe, then use a vacuum cleaner on the other end to suck the cord through. Then you can attach your cat-5 to the nylon pull cord. Works a treat.

Arsonist

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#2758814 12-Aug-2021 06:13

Blue strapping is the way to go. It's cheap and you will struggle to snap it!

https://www.bunnings.co.nz/wrap-move-20mm-x-50m-blue-packaging-strapping_p2610086

This one is 20mm wide, but its flat and you can actually fold it over easily to make it less wide.

You may be able to find blue strapping with a smaller width.

greaneyr

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#2759233 12-Aug-2021 18:57

You guys have inspired me to do a small modification to my garage. I now have an access panel at the base of the wall, where I can access the other side of the conduit. Now, I can use blower/vacuum-based methods because I can access both sides of the pipe. So much less risky now than it was, since if anything breaks I can just run another line through (provided it doesn't block of course).

Pulling on the cable directly at the pipe already feels soooo much smoother than it was, when pulling it up my the roof of the garage (presumably after it has passed through a couple of dwangs inside the wall).

Thanks for your suggestions. I did think about fishing nylon, but wasn't sure whether it would be too small and slippery to pull on. Good to know others have used it successfully in the past. But I'll figure something out.