Pulling 16mm SWA through 150 M of conduit?

[1Justin]

Would you attempt to pull 16mm SWA through 150M of existing underground conduit?

A potential job I have taken a look at. I would need to be very sure I could get it through before shelling out £££ on that much cable! (- I already advised the Customer it would have made much more sense to install a cable before filling the trench!).

Facts:
-Conduit was laid about 1 year ago. It is 50mm dia corrugated plastic type, laid in 3 sections of 50M. - I have no idea of the quality and continuity of the two joints, but the Customer will ask the contractor who laid it in.
-Conduit ~ 600mm deep through a semi-wooded garden, no special precautions such as gravel layer or warning tapes.
-Laid pretty straight for first ~60M, then takes a gentle curve perhaps 20 foot radius and turns total about 60 degrees before the end.
-String is through already to start proceedings, so I would be investing first in lots of cord, and a damn great length of blue rope.
-150M of 16mm will weigh about 150Kg!
- I also am aware it only takes a little bit of mud to make a nice plug!


Questions:
Termination for cable nose and ways to stop it snagging?
Friction being the enemy, - so Lubrication?
Best way to fix cable to rope?
Will I need a tractor ...??? (- AKA how hard can you pull safely?)
I haven't seen any longer than 100M from distributors. - Can longer single lengths be got?

Homework:
Ongoing decision as to whether I can get away with 16mm anyhow, but that's work in progress, and not my question here.

 

[Andy78]

Not a chance. That's a tiny ducting.

You should be fastening on with a small cable sock or a series of hitches tied on rope.... neither of which will fit down this ducting easily I reckon.

Which idiot put in such a small duct with no pulling pots ? If it does fit down you are gonna be digging it out in a couple of places.

 

[dan86]

personally never pulled more than 60 odd metres of swa. be interested if it can be done though

 

[telectrix]

so, even if you can manage it, how's it going to comply without digging a trench to fit warning tape? i'd run away from this one.

 

[Beavstro]

Well I suspect the danger of damaging the cable would be quite high?... Stretching it and the like if you used a tractor. If you can't do it by grunt power I'd say it needs to be dug up again.
and yeah as andy said, a cable sock or hitches, and I'd probably use hitches on preference as you could hitch it for 20 odd meters on the cable to ensure it doesn't come loose half way through the pull......
And I would also be trying to secure a rope on the entry end of the cable I case the worst happens and you break the pulling rope! At least you may be able to pull it back! Lol.

 

[mark ju]

As already stated, be far easier if there was some pits where you could pull a loop. That's a hell of a long pull. Even with a securely hitched on rope, plenty of lube, the sheer drag alone would make it a b****rd of a job.

Not planning to do it on your own are you??

Be inclined to give that a miss I think.

 

[Marvo]

I'd dig the duct up every 30 meters and pull it in sections. Whatever you do don't give them a guaranteed price or quote, this type of unknown installation would be hourly/daily rate only.

 

[Dcf]

it will fit... just.
as andy says a few half hitches and plenty tape.
but it will be a bit of a pull thats assured. a 75mm duct would have been better.
yes you can get swa in lengths longer than 100m.
do your homework on the cable size as that is a fair distance.
tractors and the like tend to stretch the cable. manpower is unfortunately the way to go.
hire a set of jacks if you can for the cable to roll off.
best of british

 

[1Justin]

Whoa. Pretty much as common sense has been shouting to me then! ie -damn near impossible, with a hint of encouragement from Dcf..

I have made no commitment to the Customer and I did suggest the possibility of needing to re-dig. I also said I'd work this one on a day rate! Recon i'll need some mates who've been eating plenty of spinach as well.

Any more opinions gratefully received.

 

[mark ju]

If you are going for it...practice your knots. Particularly the hitches around the swa.

Also as suggested hire or borrow some cable jacks and its worth while using a couple of short scaffold poles and clips to prevent the whole lot tipping forward as it gets lighter.

 

[Dizzy_Maskell]

That's a full on nightmare asking for all kinds if chaos, be sure to price it right cos that could cost you a fortune if get it wrong

 

[JD6400]

Although you are doing totally the right thing by pricing by the hour , I think you will be OK with the help of 3 or 4 others to help you .You do not say how many cores the cable will be , but even a 5 core 16mm will fit all be it some what snugly . Don't forget to meter out the cable as it is pulled so that you know where to dig and break in to the duct if needed ! You say it is in semi woodland , so I assume digging will not make much of a scar if the need arises . You should be able to borrow a set of jacks from your wholesales if you have none and a sock would be good but blue BT rope will do , I would not go to far along the cable with the knots though as this is where the dreaded friction will be the worst . With one person feeding it in to the duct , (and I mean feeding ! ) and 3 or 4 pulling you will be surprised what you can move .

 

[shanky887614]

Goodluck.

Last cable i pulled in was not fun, it might only have been network cable but in old ducting, no rope and existing cables made it a basterd.

It should have been easy and it was till last bit.

 

[Octopus]

Should we open a poll on this thread to seek peoples opinions as to whether it could be done?

I'd say definitely NOT.

 

[shanky887614]

Should we open a poll on this thread to seek peoples opinions as to whether it could be done?

I'd say definitely NOT.

No point

Can it be done? Yes

Will it be easy? No

 

[1Justin]

I like the poll! :juggle:

I was kind of thinking some sort of steel cable grabber might make for a slimmer hold on the SWA. Maybe rather than knotting the rope over, I make up a swaged steel cable with half a dozen little steel cable lassos on it and grab it with that.

- Then maybe some kind of hat (perhaps a steel pipe with a conical/reduced front end) on the front cable end to help exit the pull cable axially. I could also swage the rope loop to that which would avoid any bulky rope knots...

The conduit is all ridged though.

Lubricant then which won't damage the cable? - Vegetable oil? Tallow?

 

[shanky887614]

I like the poll! :juggle:

I was kind of thinking some sort of steel cable grabber might make for a slimmer hold on the SWA. Maybe rather than knotting the rope over, I make up a swaged steel cable with half a dozen little steel cable lassos on it and grab it with that.

- Then maybe some kind of hat (perhaps a steel pipe with a conical/reduced front end) on the front cable end to help exit the pull cable axially. I could also swage the rope loop to that which would avoid any bulky rope knots...

The conduit is all ridged though.

Lubricant then which won't damage the cable? - Vegetable oil? Tallow?

Yellow 77?

 

[1Justin]

Not having a big swage tool doesn't help.. but if one were to strip off a foot of the SWA, pull all the wires together into a cone and swage a decent sized pull cable to that, it might go as well as can be expected...

 

[Engineer54]

Corrugated plastic pipe, couldn't of chosen a worse design for such a long pull. The other thing is, how strong is this conduit /duct?? Laid at 600mm, if the wall isn't of a sufficient thickness, then there is a good chance the pipe's wall in places could have already collapsed, or starting to collapse, under the weight of the soil.


You're either going to be lucky and the pulling is going to go like a knife through butter, or as i suspect it's going to be a long pull, with one thing cropping up after another and ending up with a stretched cable at the end for all you're trouble. Use plenty of lubricant, ...you're going to need it methinks!! lol!!

 

[dan86]

yeah, you don't wanna go in dry. no one likes that. .!