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.

 

[Dave 85]

Me and my old boss tried something similar years ago. Same ducting and cable size. Duct about 80metres long with a slight dogleg at one end. We had to tie the rope to the back of my van as pulling it by hand was impossible. Managed to get it 80% of the way but the rope snapped when the SWA reached the dogleg. we dug a hole found the break and managed to finish the job but to be honest I'd never wanna do it again.

Just let the customer be aware that it might not be possible.

 

[Billythekid]

You're laughing but i'm pretty sure some daft bugger will remember your post and fill a duct with water!! lol!!
Let's hope the water isn't on a meter, and has devised some sort of method of draining it all out. ...lol!!

I can actually picture someone at the ends dipping tissue in to soak it out lol

 

[DPG]

Me and my old boss tried something similar years ago. Same ducting and cable size. Duct about 80metres long with a slight dogleg at one end. We had to tie the rope to the back of my van as pulling it by hand was impossible. Managed to get it 80% of the way but the rope snapped when the SWA reached the dogleg. we dug a hole found the break and managed to finish the job but to be honest I'd never wanna do it again.

Just let the customer be aware that it might not be possible.

E54 ain't gonna be pleased with your van antics :lol: Daz

 

[Billythekid]

OP, There is some sound advice in amongst the absurdities, I would also recommend a Mandrel to test that the ducting is still "true". Running a mandrel of a slightly smaller size than interior of duct will save you a lot of heartache.

Regards

Billy

 

[Engineer54]

E54 ain't gonna be pleased with your van antics :lol: Daz

You're right there!! lol!! That cable will have been stretched to buggery, ...and No If's Or But's about it!! lol!!

 

[Victor]

I had a job a few years ago to pull 70m through a 50mm underground conduit. Have to say NEVER AGAIN will I take on that kind of job as even the slightest rise or kink on the conduit can result in the cable sticking, in the end it was a case of digging several holes and and two days locating the conduit before being able to get the new cable plus being out of pocket on the job.

 

[1Justin]

"Never again". - That's a recurring theme! I was just talking to the hire company about their winch, and they don't really know how to use it. For instance 10mm polypropylene (~ 1 tonne break, but very stretchy, maybe need to go bigger) or spend an arm and a leg on dyneema rope (winch manufacturers say use non-stretch rope).

 

[Dave 85]

E54 ain't gonna be pleased with your van antics :lol: Daz

I expect not! Fortunately for me, I care very little for his archaic opinions.

 

[Engineer54]

I expect not! Fortunately for me, I care very little for his archaic opinions.

And unfortunately, why you will continue to stretch cables, by not knowing what the hell you're doing!!

 

[SJD]

"Never again". - That's a recurring theme! I was just talking to the hire company about their winch, and they don't really know how to use it. For instance 10mm polypropylene (~ 1 tonne break, but very stretchy, maybe need to go bigger) or spend an arm and a leg on dyneema rope (winch manufacturers say use non-stretch rope).

While I don't know much about pulling very long cables (and I'm going to be very wary if anyone ever asks me to now), why does it matter if the rope is stretchy? Could it be good to have some stretch in it, to reduce the mechanical shocks to the cable? Perhaps E54 or someone can advise.

 

[terminator]

Because you can't 'feel' when you're actually pulling the cable when it gets tight, plus all your energy is absorbed by the stretchy rope and not into moving the cable.

 

[Engineer54]

While I don't know much about pulling very long cables (and I'm going to be very wary if anyone ever asks me to now), why does it matter if the rope is stretchy? Could it be good to have some stretch in it, to reduce the mechanical shocks to the cable? Perhaps E54 or someone can advise.

Apart from what Terminator has just stated, winches work on the basis of having an adjustable clutch which is set to slip/freewheel at a predetermined torque point, applicable to manufacturers recommendations for a given size and make-up of cable. All the cable winches i've experience of, use steel draw cables (and cable socks), though i have seen some using reinforced rope draws....

The other fact is that you shouldn't even attempt pulling cables into a continuous duct, over very long distances in one go, but then that's another matter altogether.

The point is, if carrying out a cable pull correctly, and the cable winch is continuously going into slip mode, then the pull length and or design of the cable duct is Wrong, and when those that know no better hook the cable pull wire up to a van//lorry/tractor and forcibly drag the cable come what may, through!!