# Lashing conductors for services



## Flex277 (Jun 2, 2014)

This was a first for me. Was told by inspector because of the AIC on this 3000a 480v service I’m doing had to be lashed. Even said in the installation guide to be done. Has anyone ever had to do this before. I’ve heard of it but like I said this is a first for me. The transition box outside didn’t require it only if the AIC exceeded 85000. Is there anyway to calculate AIC easily?


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## telsa (May 22, 2015)

Your Poco will spit out the AIC of your Service. You just have to ask for it. They are the folks in possession of the critical numbers, anyway.

The conductors will dance something astounding under fault conditions. It can get so bad that they'll pull out of the mechanical lugs... with sparks to follow. It only takes one breaking loose to start a firestorm.


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## Southeast Power (Jan 18, 2009)

Someone did a nice job on those cables.
Ive seen plenty of lacing instructions inside of switchgear. Usually people instinctively tywrap the crap out of them and dont get called out on it very often.


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## MDShunk (Jan 7, 2007)

I've only lashed conductors when the manufacturer's literature specifically called out to do so. I put in a long AllenBradley Centerline MCC lineup 6 or 8 years ago that said to lash the conductors in the feed section, had exact pictorial diagrams, specified how many wraps, what kind of knot, what kind of rope, and the diameter of the rope. It was pretty detailed. I've never done a service with a high enough AIC to require lashing, but I've seen the lashing detail in many Poco rules books.

The OP's top picture looks strange to me, as in I don't think it's good enough if lashing was required. Perhaps the manufacturer's literature was followed to a tee? I dunno. The rope looks far too small in diameter to not become a saw when the service faults, and I see nothing between the conductors to stabilize all the phases as one solid mass. Generally lashing is much more "sturdy" than the OP's picture.


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## Flex277 (Jun 2, 2014)

MDShunk said:


> The OP's top picture looks strange to me, as in I don't think it's good enough if lashing was required. Perhaps the manufacturer's literature was followed to a tee? I dunno. The rope looks far too small in diameter to not become a saw when the service faults, and I see nothing between the conductors to stabilize all the phases as one solid mass. Generally lashing is much more "sturdy" than the OP's picture.



The rope used is 3/8 nylon rope which is what the literature required. As for spacing and wraps it required 5 wraps on every phase then drop down 12 inches and another 5 wraps. I did ask the inspector if I needed to run the rope to the enclosure as an anchor he said no. Then had me intertwine the grounded conductors as well which I thought was a little strange.


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## telsa (May 22, 2015)

In fault conditions, will they really be grounded conductors?

You might have 'fun' reading up on three-phase transformer theory. 

It'll cure your insomnia, that's for sure.

( 'Lightly touched' by Fink & Beaty: Wiley ... MANY editions. )

Some place out on the Web there is video of dancing conductors. 

( At a national testing laboratory. They jump like limp noddles.)

I did notice that your scheme used both copper and aluminum conductors. 

I must say that IS odd.


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## Flex277 (Jun 2, 2014)

telsa said:


> I did notice that your scheme used both copper and aluminum conductors.
> 
> I must say that IS odd.


In the transition cabinet? Basically transitioning from 9 runs of 600AL to 6 runs of 750CU to meet the ampacity of the service and yet have less makeup in the xfrm which was required by the POCO


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## frenchelectrican (Mar 15, 2007)

Flex277 said:


> In the transition cabinet? Basically transitioning from 9 runs of 600AL to 6 runs of 750CU to meet the ampacity of the service and yet have less makeup in the xfrm which was required by the POCO


How far is from the transformer to the main service point location ? I am thinking it have to do with distance / conductors set up.


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## Flex277 (Jun 2, 2014)

frenchelectrican said:


> How far is from the transformer to the main service point location ? I am thinking it have to do with distance / conductors set up.




About 140’ ft


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## frenchelectrican (Mar 15, 2007)

That will do it. I kinda figure it.


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