Broken Duct Pull Cord

[andyh]

During the ground works for my new build, I laid two ducts from the house to the end of the driveway. I put pull cords through both but one of them has snapped in the middle! The duct is approximately 150m long and bends underground twice. It's 63mm in diameter and although it's flexible duct with ridges on the outside, the manufacturers put an internal covering on the internal surface to make pulling cable through easier.

Just wondering if anyone has any bright ideas of how to get a new cord down the duct without digging it up. It's under various bits of landscaping so digging it up isn't really an option. I was really careful with the pull cords so don't know why it snapped - I wasn't even trying to pull anything through just testing the pull cord was o.k.!!!

Any bright ideas most welcome!

 

[ian.settle1]

During the ground works for my new build, I laid two ducts from the house to the end of the driveway. I put pull cords through both but one of them has snapped in the middle! The duct is approximately 150m long and bends underground twice. It's 63mm in diameter and although it's flexible duct with ridges on the outside, the manufacturers put an internal covering on the internal surface to make pulling cable through easier.

Just wondering if anyone has any bright ideas of how to get a new cord down the duct without digging it up. It's under various bits of landscaping so digging it up isn't really an option. I was really careful with the pull cords so don't know why it snapped - I wasn't even trying to pull anything through just testing the pull cord was o.k.!!!

Any bright ideas most welcome!

Drain rods or if not, do you have a air compressor handy you may be able to blow thin string down it and then pull a more substantial pull cord through.

 

[pushrod]

Is it on a slope? Any chance of washing something thru with some real lightweight fishing line attached eg a ping pong ball or something similar?

 

[spider]

Sorry to hear of your misfortune, maybe try this:
HSS Hire › Duct Rod

or as already been said, try blowing/sucking a cotton wool ball with string through

 

[andyh]

Thanks for all the replies guys, much appreciated.

I do have an air compressor and had thought that might work. My reservation is the area where the duct comes through the footings and rises up through the internal screed floor. I might get the string to the point where it rises but not sure it would come up the bend vertically. Worth a try though.

The duct is on a slope running down towards the house but again it's the bit where it rises from the underground trench into the house. Again it's worth a try though!

The duct rod from HSS may do the trick but I would have to use the longer one I think. 120m might not quite reach. There is still a partial pull cord in the duct so if I could somehow grab that and tie rope to the end in the house, then that might also work. However it's doubtful I'd be able to catch the loose end unless there's a loop in it.

I will try the suggestions and see what happens! Out of 8 underground ducts I laid, only this one has failed so it could be worse

 

[benji]

120mtr is a long way without drawpits , can,t you dig down half way and make one .you could hire a cobra but i don,t think there that long

yours benji

 

[spider]

Thanks for all the replies guys, much appreciated.

I do have an air compressor and had thought that might work. My reservation is the area where the duct comes through the footings and rises up through the internal screed floor. I might get the string to the point where it rises but not sure it would come up the bend vertically. Worth a try though.

The duct is on a slope running down towards the house but again it's the bit where it rises from the underground trench into the house. Again it's worth a try though!

The duct rod from HSS may do the trick but I would have to use the longer one I think. 120m might not quite reach. There is still a partial pull cord in the duct so if I could somehow grab that and tie rope to the end in the house, then that might also work. However it's doubtful I'd be able to catch the loose end unless there's a loop in it.

I will try the suggestions and see what happens! Out of 8 underground ducts I laid, only this one has failed so it could be worse

Andy,

HSS do a 250m one, have another look at the link in case you missed it

Good luck

 

[Toonlad]

Word of advice, my experience with ducts and compressors, and i know it may sound daft, but do it from the house side out. Ive seen it done a few times and the crap went up over the walls .

 

[andyh]

Word of advice, my experience with ducts and compressors, and i know it may sound daft, but do it from the house side out. Ive seen it done a few times and the crap went up over the walls .

Thanks I hadn't thought of all the crap that will be lurking in the duct! Don't think the wife would be too pleased if it covered her walls!!

 

[Davey101]

Tie a plastic bag (tesco's are best) onto a bit of string, then use a compressor to blow it down the pipe. Its surprising just how well this works (when I've watched ground workers doing it). Tie this string to some nylon rope (usually the blue stuff), and pull through. If the rope has snapped, either it was the wrong rope, or its too tight. As Benj said 120 metres is a long way, a pit halfway would be a good idea. What type and how many cables are you pulling?

 

[ash_s3]

I agree with Davey, the carrier bag and small nylon rope works a treat on long distances as the bag fills the diameter of the duct so the air from the compressor pushes it much easier.

 

[Guest123]

Small child!!!!

 

[ian.settle1]

Small child!!!!

The duct is only 63mm would have to be a lilliput child

 

[Davey101]

I also have a ferret for hire, cheap hourly rate, may bite fingers though.

 

[Guest123]

Like I said.........small.

 

[Spudnik]

As you may or may not know, the silly string that comes installed in the duct is only there for you to pull through a proper rope, which would then be used to pull your cables.

I agree with benji about the distance though.

At least one pit should be in there.

Mainly due to the fact that you will put a fair bit of strain on whatever cable you are installing when you pull it through.

 

[andyh]

As you may or may not know, the silly string that comes installed in the duct is only there for you to pull through a proper rope, which would then be used to pull your cables.

I agree with benji about the distance though.

At least one pit should be in there.

Mainly due to the fact that you will put a fair bit of strain on whatever cable you are installing when you pull it through.

Agree about the pit and will put one in about halfway which won't be too difficult as this is approximately where the car parking area begins and I know exactly where the ducts are.

I'm hoping to use one duct for CCTV cabling (CAT5 or Coax) and the other for electrics. Probably run a 10mm2 or 16mm2 SWA. There's no way I could pull a 16mm along that distance without a draw pit so will definitely put one in.

Thanks for all the advice guys.

 

[Had8Lives]

Send a rat down the duct with the rope tied round it.

 

[barney]

Borrow a ferret!!