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Comm line install


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#1 vons

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Posted 31 October 2016 - 08:48 AM

Never seen this type before, any electricians had experience with such a rig?

https://www.facebook.com/mat.tru/videos/10154645483298894/?hc_ref=NEWSFEED

#2 _litz

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Posted 31 October 2016 - 02:31 PM

That's a typical application commonly used by telephone/cable utilities (and one would presume fiber as well) for stringing "weaker" cables between poles ... it's suspended from a steel pilot cable, wrapped to it with the spiral applicator.

When you think about the requirements for a comm line on a lift, the needs aren't much different.

This post has been edited by _litz: 31 October 2016 - 02:32 PM


#3 Allan

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Posted 31 October 2016 - 06:41 PM

A spinner! We've got two lifts with comm lines done this way. Personally, I'm not a fan.
- Allan

#4 RibStaThiok

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Posted 31 October 2016 - 07:39 PM

Why is that?
Ryan

#5 Allan

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Posted 31 October 2016 - 07:43 PM

View PostRibStaThiok, on 31 October 2016 - 07:39 PM, said:

Why is that?


I've experienced a couple lashing cable failures - one bad enough to allow several feet of the lashing wire to blow into the carrier path - luckily it was the downhill side. Self supported is easier to deal with, at least in my opinion.
- Allan

#6 RibStaThiok

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Posted 31 October 2016 - 08:35 PM

Oi!!!
Ryan

#7 chuckm

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Posted 01 November 2016 - 04:55 AM

figure eight is so much easier to deal with- I can recall dragging a lasher down the hill on several lifts- a lot of extra work. perhaps it has an application for larger conductor cables-?

#8 _litz

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Posted 01 November 2016 - 02:30 PM

I could imagine if the lashing wire let loose, as it would be under a pretty good amount of tension, it would unravel and fly a good bit of ways.

Other types of tethering I've seen utilities use are simple wire clips or the above mentioned figure-eights.

This post has been edited by _litz: 01 November 2016 - 02:31 PM


#9 lift_electrical

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Posted 02 November 2016 - 06:17 AM

We have three lifts with lashed comlines. Two of the lifts have some moving towers. The lashed comline allows us to adjust the comline as the towers move down the hill. These towers also have hoffen rail imbedded in the concrete bases to keep the towers in the center line of the lift. These new tower bases were expensive. The lashing allows us to keep the boot close to the crossarm for accessibility. We use dead ends to attach the messenger to the cross arm. These are much easier to replace or remove then a strandvise if you need to adjust the comline.

The third lift, we replaced a comline that had broken several strand vise bails and the threaded rod that holds the thimble eye to the tower. On the last failure, the strandlink failed also. Its our most exposed lift to the wind. The comline was way too tight and the angle at the thimble eye/comline connection was not a straight pull. In my mind the real advantage of lashing is that the messenger is solid, you can create a loop of wire to allow plenty of wire in the boot and when the connection to the tower breaks, the stress is on the messenger, not the copper. You eliminate the strandvise and strandlink. We came up with new connection point to the cross arm that allows us to use a thimble clevis and dead end to attach to the tower. This helps with the angle being off.

This comline now is very stable in the wind. I did a lot of research on tensioning. I spoke with several lineman installing a new 161,000 volt line in a nearby canyon. All their spans are engineered for a particular tension and sag. Their technics of tensioning were very informative. Doppelmayr engineers their comlines now to give an angle as it approaches the lower tower of a span. They use a smart level to get the angle correct and then connect it. I would like to get this lifts numbers run to see how close we are to what the numbers Doppelmayr comes up with.

We purchased a lasher and find that lashing is not a problem. We practice before we work out in the field. We check our tying off of the lashing each time we are on these towers and don't seem to have any issues.

We did lash a short span to practice then cut the lashing loose to see what would happen. Its not under a lot of tension but it would be a pain to unwrap if it were a long span and you lost the lashing from the tower. You would need to unravel it from both ends.
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