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Cable Damage Reason

07/13/2017 10:50 AM

Dear Electrical Engineers

Can anyone tell what is the reason for this cable damage?We suspect rodent bite.

Same damage has been found 3 times in a week in cable trench.

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Pathfinder Tags: cable damage insulation rat rodent
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#1

Re: Cable Damage Reason

07/13/2017 11:07 AM

Among the possibilities for the damage:

  • Incorrectly manufactured
  • Overstressed due to too small a bending radius
  • Rodent
  • Someone has used a spade or other tool inadvertently near it
  • Chemical attack
  • Biological attack
  • Deterioration due to solar input
  • Sabotage
  • Etc.

<...Can anyone tell what is the reason for this cable damage?...> Yes. Any individual watching the cable becoming damaged can do this.

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#2

Re: Cable Damage Reason

07/13/2017 11:12 AM
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#3

Re: Cable Damage Reason

07/13/2017 1:51 PM

If not rodent damage, are there any goofy looking cats in the general area of your plant?

Some house cats like to chew on things they have no idea about the purpose thereof.

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#4
In reply to #3

Re: Cable Damage Reason

07/13/2017 2:24 PM

My Giant Schnauzer chewed on the electrical wiring from my R 1200 BMW.

After I got it repaired, she did it again!

Now bike sleeps behind an electric fence.

No more cable chewing

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#5
In reply to #4

Re: Cable Damage Reason

07/13/2017 4:46 PM

Her name is bike, or is she a bike?

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#6
In reply to #5

Re: Cable Damage Reason

07/13/2017 7:50 PM

Costello: I mean the fellow's name.

Abbott: Who.

Costello: The guy on first.

Abbott: Who.

Costello: The first baseman.

Abbott: Who.

Costello: The guy playing...

Abbott: Who is on first!

Costello: I'm asking YOU who's on first.

Abbott: That's the man's name.

Costello: That's who's name?

Abbott: Yes.

Costello: Well go ahead and tell me.

Abbott: That's it.

Costello: That's who?

Abbott: Yes.

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#10
In reply to #6

Re: Cable Damage Reason

07/14/2017 9:07 AM

What's on second, and I don't know is on third!

Shortstop: not a clue.

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#12
In reply to #10

Re: Cable Damage Reason

07/14/2017 9:45 AM

She, the female Schnauzer dog bit and ripped the cables from the bike´s wiring.

As this happened twice, and I caught her nibbling the plastic I covered the bike with after the second repair, I felt I had to do something a bit more drastic, so I fenced the bike with 3 strands of cable and connected it to an energizer.

After she (the dog) got 3 or 4 shocks, the three of us (dog, bike and me) live in peace and harmony again.

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#17
In reply to #12

Re: Cable Damage Reason

07/14/2017 11:20 AM

I have Schnauzer as a breed to be loving, loyal, inquisitive, good guard dogs, not trustful of strangers, and will pee on anything outdoors (maybe less with female ones).

They can be a stubborn little dog to train, as most Germans are. Once you get them past goose-stepping, and wearing monocles, it is all good from there on.

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#7

Re: Cable Damage Reason

07/13/2017 10:14 PM

You have not told us the voltage class, type of insulation, type of installation, and/or the type of covering fill. Without knowing any of these, the damage looks consistent with low voltage thermoplastic insulation directly buried in rock fill, possibly with traffic or equipment movement directly above the trench.

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#8

Re: Cable Damage Reason

07/13/2017 11:11 PM

On my computer, the cable part of the image is very dark. After adjusting a few parameters, I can see a bit more:

I don't see any evidence of tooth marks, so until I see a more detailed image, I'd rule out animal damage.

It looks to me like cracking due to age, exposure to UV or chemical, or to mechanical stress.

When you say "in cable trench", do you mean that it was direct burial, and you found this after digging it up? If so, It could be damage from the digging tools/machines...

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#11
In reply to #8

Re: Cable Damage Reason

07/14/2017 9:43 AM

Cable is laid in cemented cable trench,not filled.Cable is 185sqmm 3.5 core , 600V ,CU/PVC/PVC.

No digging tool or chemical.

But found water in cable trench.

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#13
In reply to #11

Re: Cable Damage Reason

07/14/2017 9:47 AM

seems to have been burned by a short circuit spark

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#16
In reply to #13

Re: Cable Damage Reason

07/14/2017 11:18 AM

That is certainly believable! Covering the concrete trench with concrete cover/lid that is removable would require a reusable gasket also, and I expect the cost, inconvenience would put it out of question.

Obviously, any flaw in an open trench where rain water could accumulate with cooling tower drift salts, or ocean spray salts, where there is a conductive path to ground is a really bad idea.

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#18
In reply to #13

Re: Cable Damage Reason

07/14/2017 11:29 AM

Not necessarily an actual short-circuit type spark. Any concentrated electric fields could conceivably be vaporizing water, accelerating the damage to the plastic.

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#19
In reply to #18

Re: Cable Damage Reason

07/14/2017 11:34 AM

could that happen as you stated with high voltage (near insulation break-down), perhaps in a 90 degree bend?

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#9

Re: Cable Damage Reason

07/14/2017 12:30 AM

In my opinion, it is a low voltage flexible cable ,sheathed with a kind of black rubber. A layer -of fire protection material, may be-it was smeared on the cable surface and it cracked when it was dry and bent after then.

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#14
In reply to #9

Re: Cable Damage Reason

07/14/2017 9:48 AM

Cable is laid in cemented cable trench,not filled.Cable is 185sqmm 3.5 core , 600V ,CU/PVC/PVC.

No digging tool or chemical.

But found water in cable trench.

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#15
In reply to #14

Re: Cable Damage Reason

07/14/2017 11:02 AM

PVC doesn't show well in some water immersion tests, especially 60C rated versions. If that is your primary insulation, might be a clue. The data on water immersion testing is somewhat dated, one in 1959,

http://www.dtic.mil/dtic/tr/fulltext/u2/656243.pdf

here is a more recent sample. Page 8-7, for instance

http://www.aluminum.org/sites/default/files/Chapter%208%20Insulation%20and%20Related%20Cable%20Components.pdf

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#20

Re: Cable Damage Reason

07/14/2017 12:45 PM

This is the cable image. Approx.overall dia 61.5 mm. The bend radius seems to be about 8 times the diameter [it is as recommended]. No sign of mechanical abuse and no PVC jacket damage sign. Only the outside sprayed material is exfoliated.

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#21
In reply to #20

Re: Cable Damage Reason

07/16/2017 11:38 PM

"This is the cable image. Approx.overall dia 61.5 mm. The bend radius seems to be about 8 times the diameter [it is as recommended]. No sign of mechanical abuse and no PVC jacket damage sign. Only the outside sprayed material is exfoliated."

Sounds like you have at least two " aliases", (1) ahmedhassankhan and (2) 7anoter4

Other than that, your picture sucks or I need to get new glasses. The shadows cover most of the image.

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#22
In reply to #21

Re: Cable Damage Reason

07/17/2017 12:41 AM

You apparently wrote this response as a reply to post #20, and quote text therefrom, but your discussion of the picture must refer to the original post.

The picture in post #20 is quite acceptable, and in fact I'm betting that it was taken from either the cable fabricator's or the cable distributor's website. The cable end has been very carefully prepared to show all the layers, but with stripping way too short for any actual use I'm familiar with.

I indicated in post #8 that the original image was poor, and even went to the trouble to modify it to bring out the shadows as best I could. I had hoped that the OP would provide one or more better images, but so far, he hasn't taken the hint!

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#23

Re: Cable Damage Reason

07/17/2017 12:50 AM

Thank you, dj95401.However, you don’t have to be ahmedhassankhan in order to see the obvious. If you can stop a little and look in the web for IEC 60502-1 or BS power cable manufacturer catalogue you’ll find this. The bending radius you can measure it from the ahmedhassankhan open post.

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#24

Re: Cable Damage Reason

07/19/2017 3:23 AM

Can we get a couple more pictures? It is hard to tell if some of the dark areas are damage or shadow.

A close up of the edge of the entry/penetration would be informative.

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