Manufacturing fault in cable

[SLIPSHOD & SLAPDASH]

Rather than hijack another thread i thought i would put a few quite boring pictures here.

We had carried out insulation resistance testing on this cable months back, its for one of 3, 3kw immersion heaters in a house. A year later it gets energised & Zs tested. I am imformed by my guy on site that immersion must be faulty as it trips the 16A Rcbo every now & then. Then every couple of days. I was on site all of last week and the Rcbo would not reset. After testing i realised there was a cable fault (95% finished house)

To cut this short i cut the cable where it disappeared into the abyss and was surprised the top end which could be pulled back had the fault. New leg pulled in, jointed, tested & turned on.

I then started cutting the 8m long length of 2.5 Tw&e in half & in half until i had this faulty (L to E) piece of cable in my hand

It looked ok so i sliced open one side

Still looked ok inside

Turned it over, sooty

Had a close look & found this. You can see where something has gone through at about 45 degrees. It scraped the cpc enough to give a rough edge that pierced the brown insulation. The sheath was undamaged though. I pulled the cable in and this part was under a sealed floor. I can only think it was like that before the sheath was extruded at the factory

 

[NozSpark]

Have you told the cable manufacturer about this?

Would they be interested or not though?

---------- Post Auto-Merged at 22:44 ---------- Previous post was made at 22:43 ----------

I guess this fault didn't show up in your testing?

 

[SLIPSHOD & SLAPDASH]

It was clear on testing, i recon the rough edge on the cpc worked its way into the brown insulation and the arcing and carbon build up affected the insulation later. No name on the bit of cable i pulled out, only the BASEC numbers

If you click on the top bit of the last 2 pics (to enlarge) you can see how rough the cable is. Not bad pics for my Samsung Galaxy s phone

 

[kerching]

What 'make' was the cable?

 

[NozSpark]

That's a shame, it would be interesting to see what their response was.

 

[SLIPSHOD & SLAPDASH]

All the cable has is BASEC 141 BS 6004 6242YH 2X2.5+1.5MM2 PX96 CE............................. Anyone ?

 

[Manator]

Thanks slips, I take it this is the fault you spoke about on another thread? Thanks for the photo's, I bet that was one fault you had never even thought existed. Am I correct in thinking that the sheath was undamaged? or did I miss that.

 

[SLIPSHOD & SLAPDASH]

Yep, no damage as shown in the first 2 piccies. I have never seen or heard of this before.

 

[kme]

I believe Batty had a piece of cable with a low ins. reading, when I was there.

If tested at 1KV, you could hear the breakdown; yet the outer was undamaged.....

I intended to get the meters in, and try to determine where the fault was; but managed to totally forget, until now.

I think it highlights a requirement to do an IR test on full rolls of cable ( I now do an end-to-end resistance, too), before using any!

 

[Manator]

I have never seen this before, but thanks to the vigilance of people like yourself I am now aware that this fault is possible. Well done on finding this fault, I think that alone is worthy of a scoob.

 

[SLIPSHOD & SLAPDASH]

All our cable comes from 'Proper' wholesalers so i would assume its not some Turkish snide.

Unrelated to this fault, who can tell me what 100m of each of the common size cables resistance should be, so this can also be checked on the drum to ensure its not undersized ?

 

[kme]

1mm - 100M - 1.81 ohms

1.5mm - 100M - 1.21 ohms

2.5mm - 100M - 0.741 ohms

4.0mm - 100M - 0.461 ohms

6.0mm - 100M - 0.308 ohms

10mm - 100M - 0.183 ohms

16mm - 100M - 0.115 ohms

 

[Zeespark]

Slips, it sounds like you cable came from a company named PX Cables. When I was working at Edmundsons, we would use PX as a stop gap between orders from AEI Cables.

PX Manufacturing & Distribution Company Limited

AndyGuinness

 

[SLIPSHOD & SLAPDASH]

Slips, it sounds like you cable came from a company named PX Cables. When I was working at Edmundsons, we would use PX as a stop gap between orders from AEI Cables.PX Manufacturing & Distribution Company Limited

AndyGuinness

Thanks for that. Does not ring any bells so i will make a few enquires.

 

[Zeespark]

I could be wrong, I was going on the PX marking on the cable, as most suppliers mark their ID on their cables. PX dont have cardboard sleeves on their cable drums like AEI or Prysmian do, and only a small label on their reels for ID purposes.

AndyGuinness

 

[SLIPSHOD & SLAPDASH]

I looked also, PX isnt on their list

 

[Zeespark]

My apologies then Slips. Do you have any idea (to within a few weeks) of when the cable was installed? if so your wholesaler should be able to trace where the cable came from if they look up their purchase records.

AndyGuinness

 

[SLIPSHOD & SLAPDASH]

It could of come from 5 different places. Cable was installed a year ago & only just livened up

 

[batty]

Does sound like PX cables to me I try to avoid it these days use Prysmian if I can.

 

[Jono Pashley]

Since a similar incident last year ive taken to testing the cable on the reel before even doing anything.