Huge Cable Pull

[MD88]

Hey guys, we're gearing up to try pulling one helluva cable run, just wondering if anybody had any experience with one of this magnitude.

3C-750MCM MV-105 cable in 6" PVC conduit, and the run is about 1000' long. It's pretty much straight... it has a vertical 90 at one end to come out of the ground, then comes straight into a vault at the other end. There are 2 big manholes along the way, but the access hatch is too small to fit the bending radius of the cable (so, basically we can't go in and out of the same hole). This leaves us stuck with putting the reel at one end, and the tugger at the other end, if we are to do it without splicing.

Any thoughts?

Thanks

 

[BJ Conner]

Got a vendor?

Got a vendor?

Hey guys, we're gearing up to try pulling one helluva cable run, just wondering if anybody had any experience with one of this magnitude.

3C-750MCM MV-105 cable in 6" PVC conduit, and the run is about 1000' long. It's pretty much straight... it has a vertical 90 at one end to come out of the ground, then comes straight into a vault at the other end. There are 2 big manholes along the way, but the access hatch is too small to fit the bending radius of the cable (so, basically we can't go in and out of the same hole). This leaves us stuck with putting the reel at one end, and the tugger at the other end, if we are to do it without splicing.

Any thoughts?

Thanks

Who made the cable? They are usually helpful if you contact them. That's a lotta $$ in cable- they don't like to see anything happen to "their" cable.
Otherwise:
1.) Do your pull calc.
2. )Don't try to pull it with kellems etc. USe heads and a bridel.
3.) Set up so your feeding in at the 90.
4.) Mandrel, swab, and prelube the cable. HAve a man in each vault lubing the cable as it goes through.
5.) IF you have to use sheaves in the intermediate manholes - think ferris wheels not well pulleys. The bigger the radius, the less sidewall pressure.
More in while.

 

[220/221]

This leaves us stuck with putting the reel at one end, and the tugger at the other end, if we are to do it without splicing.

Any thoughts?

Thanks

I'd put the tugger at one end and the cable at the other.



My logic says to feed the cable in the straight end so you are not pulling all of it thru the well lubed 90.

Run something thru the conduit first to make sure there is no debris to damage the wire.

Lube is your friend.

Connect you wires/cables well

3.) Set up so your feeding in at the 90.

why?

 

[MD88]

Haha, good! Well, the fact that nobody is saying "YOU ARE SCREWED" is making me a feel a whole lot better. Good idea putting a guy with lube at each manhole, hadn't thought of that. I'm not the one doing the pulling (thankfully we have a professional crew to do that) but as a lowly observer I was starting to get worried.

Btw, the plan is to feed it off the reel right down into the 90, and pull from the vault end.

Thanks

 

[220/221]

Btw, the plan is to feed it off the reel right down into the 90, and pull from the vault end.

With one 90, it's not going to be an issue but I figured 1000' of rope would be easier to pull around a 90 than 1000' of cable.

 

[BJ Conner]

More

More

Who made the cable? They are usually helpful if you contact them. That's a lotta $$ in cable- they don't like to see anything happen to "their" cable.
Otherwise:
1.) Do your pull calc.
2. )Don't try to pull it with kellems etc. USe heads and a bridel.
3.) Set up so your feeding in at the 90.
4.) Mandrel, swab, and prelube the cable. HAve a man in each vault lubing the cable as it goes through.
5.) IF you have to use sheaves in the intermediate manholes - think ferris wheels not well pulleys. The bigger the radius, the less sidewall pressure.
More in while.

I did the pull calc with Polywater PP3000 It said the tension is about 2,500 with a COF of .21 and 4,800 with a COF of .4. The actual is somewhere between.
Rig everything solid. Anchor everything well. a bolt pulling out is a potential killer.
Don't let any one put a 441-6 in your last pipe and use it to pull out with.
http://www.greenlee.com/cat_docs/Cable_Pulling09.pdf
Check side wall pressure with the vendor. At, 2,500 lbs tension a 3 ' radius sheave is going to give you 833 lbs. Thats more than some manufactures allow.
Remember the 6Ps. 750 cable is arround $50/ft, the whole job could be $150-200K. Owners don't like it when something goes south.

 

[Cow]

The last time our company did a large MV cable pull we had someone else monitoring the pull tension during the process. I don't know if it was a sub we hired or someone directly from the manufacturer that oversaw the pull?

It was a heck of a lot shorter than the one you're about to do too, it was only about 300-400' or so but they were 1000 MCM.

 

[ceb58]

Haha, good! Well, the fact that nobody is saying "YOU ARE SCREWED" is making me a feel a whole lot better. Good idea putting a guy with lube at each manhole, hadn't thought of that. I'm not the one doing the pulling (thankfully we have a professional crew to do that) but as a lowly observer I was starting to get worried.

Btw, the plan is to feed it off the reel right down into the 90, and pull from the vault end.

Thanks

To make you feel better YOU ARE SCREWED
Last big pull I did we had guys at four manholes with buckets of lube. That stuff is cheap in the overall scheme of things

 

[BAHTAH]

Cable Pull

Cable Pull

When working for a large utility pulling lead cable we would always do what BJ Conner mentioned as item(4). I cannot stress enough that you pull a mandrel and cups and brushes through the conduit prior to pulling any cable. One rock in the conduit can make for a bad day. Sometimes we would also pull a short piece of the cable, maybe six feet long through the conduit and check for any damage. Being straight and feeding at the 90-degree end I don't think your pulling tension would be a problem. I can't remember for sure but I think the anchors in our vaults were rated for 6000 lbs and over the years I can only remember having one fail and that was because we had to leave a 1000ft run of 3con-500kcm lead cable sit in the duct for a couple of weeks and then had to pull it out. A clean duct, plenty of lube and not having to stop the pull until complete and you should be fine. I think all of BJ Conners points are good.

 

[LarryFine]

3.) Set up so your feeding in at the 90.

Relly? So almost the entire length of the wires must pass through the elbow?

My logic says to feed the cable in the straight end so you are not pulling all of it thru the well lubed 90.

Same here. I'd rather pass the first 10' through the elbow than the first 990'.

 

[masterinbama]

To make you feel better YOU ARE SCREWED
Last big pull I did we had guys at four manholes with buckets of lube. That stuff is cheap in the overall scheme of things

Just don't let the guys in the holes until the cable has passed all the way through. The fly back on that rope could cut a man in half.

 

[defears]

Feeding down into a 90 is usually better than pulling up at the end because the weight of the wire pushes it into the 90 with no effort. There is almost no sidewall pressure. It's almost like there is no elbow. Pulling up the 90 with the whole weight of 1000 ft of 750 isn't fun. That last 10ft is where it will snap,if it does.

 

[LarryFine]

Feeding down into a 90 is usually better than pulling up at the end because the weight of the wire pushes it into the 90 with no effort. There is almost no sidewall pressure. It's almost like there is no elbow. Pulling up the 90 with the whole weight of 1000 ft of 750 isn't fun. That last 10ft is where it will snap,if it does.

Hmmm. Something to ponder.











Okay, I've pondered it. I think you're right.

 

[Ragin Cajun]

When working for a large utility pulling lead cable we would always do what BJ Conner mentioned as item(4). I cannot stress enough that you pull a mandrel and cups and brushes through the conduit prior to pulling any cable. One rock in the conduit can make for a bad day. Sometimes we would also pull a short piece of the cable, maybe six feet long through the conduit and check for any damage. Being straight and feeding at the 90-degree end I don't think your pulling tension would be a problem. I can't remember for sure but I think the anchors in our vaults were rated for 6000 lbs and over the years I can only remember having one fail and that was because we had to leave a 1000ft run of 3con-500kcm lead cable sit in the duct for a couple of weeks and then had to pull it out. A clean duct, plenty of lube and not having to stop the pull until complete and you should be fine. I think all of BJ Conners points are good.

EXCELLENT advice! Even sand can give you problems. Run rags after the brushes. It must be clean! Keep the manholes clean as well.

Best to you!

RC

 

[220/221]

Hmmm. Something to ponder.











Okay, I've pondered it. I think you're right.

Hmmmm....I gon't get it. Let's say there is 500 to 1000 pounds of pressure on the cable at the mid point of the pull.

Can you somehow push the cable down with enough pressure to eliminate sidewall pressure? I think the most you could possibly apply via the cable weight would be a hundred pounds.

Dammit. Now you have me thinking about it. You may be right.

 

[don_resqcapt19]

...
Can you somehow push the cable down with enough pressure to eliminate sidewall pressure? I think the most you could possibly apply via the cable weight would be a hundred pounds. ...

The side wall pressure is a function of the pulling tension at that point in the pull and the radius of the bend. The closer the 90 is to the feed end, the less the pulling tension is at that point and the less the sidewall pressure will be as the wire goes around the 90.

 

[M4gery]

Did you use a rigid 90?

1,000' of rope is an awfully long saw. IMO, that's another reason to feed into the 90 end of the run. I'd rather have lubed up conductors than high tension rope.

 

[K8MHZ]

Feeding down into a 90 is usually better than pulling up at the end because the weight of the wire pushes it into the 90 with no effort. There is almost no sidewall pressure. It's almost like there is no elbow. Pulling up the 90 with the whole weight of 1000 ft of 750 isn't fun. That last 10ft is where it will snap,if it does.

I got to see that actually happen!

I was just leaving a building and was passing a pull point another EC was doing. It was an 1100 foot run of 750's or so. I just happened to glance over as the head broke off. It made a pretty good bang. The head just made the last 90 and was about a foot underground when it broke.

They did save it by doing some digging and conduit busting.

 

[zog]

test that cable before and after the pull. DC hipot can be damaging so you will need to do an AC VLF test.

 

[weressl]

The side wall pressure is a function of the pulling tension at that point in the pull and the radius of the bend. The closer the 90 is to the feed end, the less the pulling tension is.

Have the pull calculated by the cable manufacturer, verified and signed by the Company who does the pull and record the pulling tension from beginning to end and have a torque limit set on your gear. (Although any of these suggestions would be superfluous for anyone who SHOULD be attempting a pull like this.)