# 4160 cable



## firelient (Dec 15, 2010)

How Long ago did you start using Medium voltage cable ie 5k ? Just looked at a job where 500 mcm cable shorted out with 4160. looks like regular cable haven't found any markings on it yet. All I ever seen with 4160 was shielded cable. am I missing something.. Thanks


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## Big John (May 23, 2010)

It's probably unshielded MV-90. It's pretty common with 5kV systems because terminations can be done without stress cones. It looks a lot like regular 600V wire, but it will say on it that it's rated for 5kV.

-John


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## bruce6670 (Apr 27, 2010)

I know a guy who recently got bit really bad when checking this type of cable. 

He was trouble shooting a 480v system. And after checking voltage at a number of locations with his 600v meter, he mistakenly checked a 4160v circuit with the same meter. He lived but has some permanent damage to his hand. This guy is a seasoned vet. He just looked at the cable and thought it was the same 480v circuit he was trouble shooting. Bad mistake.

I have never seen this cable before. I will definitely be watching out for it though.

edit: Forgot to mention that the meter blew up in his hand.


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## socalelect (Nov 14, 2011)

What is a stress cone?


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## glen1971 (Oct 10, 2012)

bruce6670 said:


> I know a guy who recently got bit really bad when checking this type of cable.
> 
> He was trouble shooting a 480v system. And after checking voltage at a number of locations with his 600v meter, he mistakenly checked a 4160v circuit with the same meter. He lived but has some permanent damage to his hand. This guy is a seasoned vet. He just looked at the cable and thought it was the same 480v circuit he was trouble shooting. Bad mistake.
> 
> ...


Had a buddy of mine do the same thing about 2 years ago.. No long term damage to him, but I don't think he'll put a meter on again without being certain.. He has about 20 years in the trade...


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## backstay (Feb 3, 2011)

socalelect said:


> What is a stress cone?


This from another site.


NormGA (Electrical)31 Jul 01 16:59 
Stress cones are usually not required on 2.4/4 kv power cables in conduit, but are required on higher voltages. Imagine concentric tubes of electrical field lines inside the cable, being confined by the outer semiconducting shield. The entire cable from the center conductor to the semicon jacket then is full of these tubes. When terminating the cable it is of course cut, then the semicon jacket is stripped back for a distance appropriate to the voltage. If the cable is then energized you can imagine the tubes of the electrical field in the vicinity of the end of the semicon jacket will simply curl back around extremely sharply, while those near the center will curl back around at a greater arc. The effect of this will be ultimate failure of the dielectric at the point where the semicon is terminated. What you would have in effect is say 7200 volts separated from the grounded semicon jacket by only 1/4 inch of dielectric. The solution to this is to install a "stress cone". If you can now imagine a metal cone, say about 3 to 4 inches in diameter by 6 inches long, with the pointed end cut off, inserted onto the cable, small end first, to the end of the semicon jacket. If the cable is now energized you can see that the tubes of the electrical field are curved in a much greater arc, so the electrical "stress is relieved". In practice there are several ways to do this. One is to use a manufactured "stress cone", which actually looks like a double ended cone. One end is semicon, the other is dielectric. The semicon is slid down so that it makes contact with the semicon jacket of the cable. A taped up stress cone can be made by using insulating tape to make about a 3+ inch diameter ball at the end of the semicon jacket, then applying semicon tape to form the cone. The semicon is made into a cone, and not allowed to curve back. There is one method that uses some sort of chemical to make a stress relief that looks like a sieve, but I don't understand how that works. The large porcelain potheads have stress relief built in.


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## bobelectric (Feb 24, 2007)

Any cables over 2 kv now need to be shielded. That put me outta the game.


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## wwilson174 (Apr 25, 2008)

On a shielded cable the stress between the conductor and the shield is greatest where the conductor is terminated , technically this is the result of the voltage gradients converging, the result is a greater stress on the insulation at this point.
The solution is increasing the amount of insulation between them at this point,using a technique of building a tapered layer of insulation at this point using tape. Known as a stress relief cone. BillW


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## bobelectric (Feb 24, 2007)

You kids should learn this art! It pays!


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## MDShunk (Jan 7, 2007)

bobelectric said:


> You kids should learn this art! It pays!


The art has faded somewhat. "There's a kit for that" is the answer to most of this type of terminating.


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## Zog (Apr 15, 2009)

MDShunk said:


> The art has faded somewhat. "There's a kit for that" is the answer to most of this type of terminating.


That is true, still takes some practice and not as easy as you would think for a first splice but not the art form it used to be. I have worked with some talented splicers and seeing them pour a lead splice is neat to watch.


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## firelient (Dec 15, 2010)

glen1971 said:


> Had a buddy of mine do the same thing about 2 years ago.. No long term damage to him, but I don't think he'll put a meter on again without being certain.. He has about 20 years in the trade...


We had a guy do the same thing took out main substaion.. been 8 years and he stills wears a suit burnt 70% of body melted his clothes off and burnt another man 8' away. Only found small parts of meter..Hard lesson learned.


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## glen1971 (Oct 10, 2012)

bobelectric said:


> Any cables over 2 kv now need to be shielded. That put me outta the game.


Only an NEC requirement.. Not CEC, yet...


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## bobelectric (Feb 24, 2007)

Lucky. I have 400' of mv-90 4/o I can't use.


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## denny3992 (Jul 12, 2010)

bruce6670 said:


> I know a guy who recently got bit really bad when checking this type of cable.
> 
> He was trouble shooting a 480v system. And after checking voltage at a number of locations with his 600v meter, he mistakenly checked a 4160v circuit with the same meter. He lived but has some permanent damage to his hand. This guy is a seasoned vet. He just looked at the cable and thought it was the same 480v circuit he was trouble shooting. Bad mistake.
> 
> ...


Was this at car tech in reading pa? I heard they had a meter blow up a cupl weeks ago!


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## bruce6670 (Apr 27, 2010)

denny3992 said:


> Was this at car tech in reading pa? I heard they had a meter blow up a cupl weeks ago!


No. Somewhere in NJ. Not sure where.


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