Author Topic: 4 out of 5 vendors are scamming people with wrong crosssection of cables  (Read 6496 times)

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Offline eTobeyTopic starter

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I have ordered cables from 5 different places (Germany). 4 of them had sent me cables that had about 20% less crosssection than advertised. I measured via visual and electrical methods, so there is no doubt about my measurements. One one ocassion, the outer diameter had me feel that it was to little, and sure enough it was...

Have you ever checked on the cross section?

« Last Edit: May 01, 2024, 06:37:50 pm by eTobey »
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Online ejeffrey

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What kind of cables?  Power or signal?  Were they advertised to conform to a particular industry spec or just a specific size?

 
 

Offline eTobeyTopic starter

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What kind of cables?  Power or signal?  Were they advertised to conform to a particular industry spec or just a specific size?
I wrote in this section of the forum, because it has the word "power" in it.  ;)

But i also found in one delivery where i ordered a few 0.35mm2 cables, one cable to beeing substantially less.

Seemingly, many people just trust what there is advertised. But you cant trust anything nowadays...

"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 

Offline mariush

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Do they use the exterior diameter (with insulation), or the inner diameter (as if you stripped)

On stores like Digikey , Newark and others you get a datasheet for the cable where it tells you how many strands of wires are used, and what's the gauge of each strand.

See for example https://www.digikey.com/en/products/filter/single-conductor-cables-hook-up-wire/474  you see there a column with number of strands and thickness of each strand


edit : you seem to be in Germany so TME.eu may work better : https://www.tme.eu/en/katalog/wires-and-cables_112533/

You can see all the parameters at the Stranded cables section : https://www.tme.eu/en/katalog/single-core-cable-strand_100147/
« Last Edit: April 28, 2024, 06:29:56 pm by mariush »
 

Offline Stray Electron

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I have ordered cables from 6 different places (Germany).
Have you ever checked on the cross section?


   Where were the cables made?   Undersizing of wire and cables made in China has been widely reported on this and other sites.   A lot of the wire is also reported to be made some kind of junk alloy that isn't solderable.  I've learned to not trust the ratings of anything made in China.

  A few years ago my 730 pound Miller welder got dumped unto the ground when the frame of my Chinese made 900 pound rated trailer bend under the load and within 30 seconds of placing the welder on it and before we had moved it even an inch.
 

Offline eTobeyTopic starter

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   Where were the cables made?   Undersizing of wire and cables made in China has been widely reported on this and other sites.   A lot of the wire is also reported to be made some kind of junk alloy that isn't solderable.  I've learned to not trust the ratings of anything made in China.

I dont know, and the vendor wont tell me of course.

Only 2 of them were amazon and ebay (not chinese - and seemingls reputable ones), but the other had their own websites and did not have bad ratings. I think they are not aware of it either. One of them got quite furious, as he strongly insisted it was 6mm2 even though i told him two measurement methods showed otherwise (This one sold photovoltaik stuff).

Still my question is unanswered:
Have you ever checked on the cross section?
« Last Edit: April 28, 2024, 06:44:19 pm by eTobey »
"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 

Offline Karel

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Quote from: eTobey
Still my question is unanswered:
Have you ever checked on the cross section?

No, because I order from Digikey/Mouser/Farnell.
 

Offline Bud

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  A few years ago my 730 pound Miller welder got dumped unto the ground when the frame of my Chinese made 900 pound rated trailer bend under the load and within 30 seconds of placing the welder on it

Must observe the 11th Commandment: "Thou shalt downscale all Chinese specifications by a factor of 2".
Facebook-free life and Rigol-free shack.
 
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Offline eTobeyTopic starter

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No, because I order from Digikey/Mouser/Farnell.
When there are so many cases of wrong cross sections, i would be very curious not caring about big names.
"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 

Offline Stray Electron

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   Where were the cables made?   Undersizing of wire and cables made in China has been widely reported on this and other sites.   A lot of the wire is also reported to be made some kind of junk alloy that isn't solderable.  I've learned to not trust the ratings of anything made in China.

I dont know, and the vendor wont tell me of course.

Only 2 of them were amazon and ebay (not chinese - and seemingls reputable ones), but the other had their own websites and did not have bad ratings. I think they are not aware of it either. One of them got quite furious, as he strongly insisted it was 6mm2 even though i told him two measurement methods showed otherwise (This one sold photovoltaik stuff).

Still my question is unanswered:
Have you ever checked on the cross section?

   I've never measured any that I'm aware of, but I've seen dozens of Chinese made wires and cables (including steel cable, aka "wire rope") that were obviously smaller than it was labeled.  Personally I haven't bothered to measure any of the Chinese electrical stuff because, so far, I've been able to buy reputable American made brands that I know that I can trust.  I've learned the HARD WAY, so whenever it's something that matters, I now go out of my way to good American, Japanese or western European brands even though they cost a lot more than the Chinese stuff.

   I DID look at probably 40 different lots of wire rope and I did measure a lot of it and ALL of the Chinese made stuff was much smaller than claimed.  Also I really have no idea what kind of steel it was made of so I finally bought 1000 feet of US made wire rope surplus.  My off road vehicle (1952 Dodge m-37) weighs almost 7,000 pound unloaded and calls for 1/2" IPS (Improved Plow Steel) wire rope that is rated for a 27,000 pound working load.  I found the stuff that the Chinese were selling was less than 7/16" and it BROKE at about 9,000 pounds. 

   it's the same story as my Chinese made trailer, it will almost meet the stated load but there is NO safety margin. 
 

Online ejeffrey

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No, because I order from Digikey/Mouser/Farnell.
When there are so many cases of wrong cross sections, i would be very curious not caring about big names.

I've never measured explicitly, but if you told me you bought genuine belden wire from and authorized distributor and it was smaller than what it says on the box I'd be surprised and I would go measure some of the wires in my shop.  The fact that 5 different wires purchased from random resellers on Amazon or eBay were counterfeit it doesn't surprise me at all.
 

Offline thermistor-guy

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...
   it's the same story as my Chinese made trailer, it will almost meet the stated load but there is NO safety margin.

There's a Chinese EE located near me, running a transformer rewinding business. He's from Shanghai. Many years ago, he told me that
Chinese electronics are made to a price, and they will only just meet spec. (if at all).

He went on to say that, unlike US or EU equipment, Chinese-brand equipment will not have any overload capability, not even
short-term overload.
 

Offline f4eru

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I measured via visual and electrical methods, so there is no doubt about my measurements.
Pleaae publish your measuremenets.
 
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Offline Siwastaja

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Have you ever checked on the cross section?

Another interesting question would be, how did you measure it? I ask because measuring cross section of a multi-stranded wire is not trivial at all. Which is also why, to answer your question: I have never checked. I think the risk of me measuring incorrectly would be larger than the manufacturer lying.

One thing to consider is also tolerances. In engineering, everything comes with a tolerance. Manufacturer's job is to guarantee their product is within tolerances. If they can improve the manufacturing process, they can save costs by making undersized product which is still within tolerances, and no one would be lying.
 

Offline eTobeyTopic starter

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... I ask because measuring cross section of a multi-stranded wire is not trivial at all. Which is also why, to answer your question: I have never checked. I think the risk of me measuring incorrectly would be larger than the manufacturer lying.

Current, voltage drop and ust a few calculations, and then you have the cross section. Nowadays with internet i would call this trivial.

I could not find the very same measurments, but i can give you an example, that is as good. (Scamed by the PCB manufacturer, as he did not mention a tolerance of 20%. Seems to be a chinese thing, yes).
"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 

Offline mzzj

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... I ask because measuring cross section of a multi-stranded wire is not trivial at all. Which is also why, to answer your question: I have never checked. I think the risk of me measuring incorrectly would be larger than the manufacturer lying.

Current, voltage drop and ust a few calculations, and then you have the cross section. Nowadays with internet i would call this trivial.

I could not find the very same measurments, but i can give you an example, that is as good. (Scamed by the PCB manufacturer, as he did not mention a tolerance of 20%. Seems to be a chinese thing, yes).
Maybe trivial question but what did you use for reference copper conductivity value?
100% IACS gives different results than actual cabling standard IEC 60228

Out of curiosity I measured bunch of wires and bit suprisingly worst offender is single strand 1.5mm2 cable from some european manufacturer: (every cheapo chinese wire passes the  IEC 60228)
« Last Edit: April 29, 2024, 06:24:25 pm by mzzj »
 

Offline eTobeyTopic starter

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Maybe trivial question but what did you use for reference copper conductivity value?

Out of curiosity I measured bunch of wires and bit suprisingly worst offender is single strand 1.5mm2 cable from some european manufacturer
I used the standard values that were in the calculator.

How did you measure the resistance?

In the end, i also received cables that had the values i calculated, so there is nothing wrong with my calculations.
"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 

Online ejeffrey

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You are being pretty evasive, not providing a example product, data sheet, measurement, photo, or really anything supporting your claim except for somehow a microscope image that appears to be of a PCB trace and which seems completely irrelevant?  So it's no surprise everyone is being skeptical of your measurements. 

If you can't provide numbers and references there isn't really anything for anyone here to say.
 
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Offline mzzj

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How did you measure the resistance?

In the end, i also received cables that had the values i calculated, so there is nothing wrong with my calculations.
Mystery wire, mystery supplier, mystery method and mystery calculator.

Your calculator probably uses theoretical values calculated with 100% IACS conductivity and manufacturers aim close to IEC 60228 maximum value as they can reliably get as it provides best profits.
Note that IEC 60228 has different maximum resistance for same cross section area depending if it fine or coarse stranded wire. Difference between fine-stranded wire and 100% IACS is almost 15%

I used 4-wire measurement with 1A current supplied by Agilent 6632B power supply, voltage loss measured with dvm, cable lenght with tape measure.

Seemed like good idea to twist the wire strands tightly and place the kelvin wire connections with at least 20mm gap on the wire.
Without twisting and some gap between the kelvin wire connections the results were bit unstable, probably due to unstable connection and current distribution between wire strands.
« Last Edit: April 29, 2024, 09:33:49 pm by mzzj »
 

Offline jonpaul

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We use only genuine Belden wire and cable as our work is important

The Chines commi junk eg eBay, Ali express is penny wise and pound foolish.

Try a magnet on the ChiCom wire to detect the iron.

Return for refund all the junk

Jon
Jean-Paul  the Internet Dinosaur
 
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Offline Siwastaja

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I used the standard values that were in the calculator.

You were asked what resistance value you used. Your answer is "the one in the calculator". What the heck even is "the calculator"?

Given this glaring lack of scrutiny and total absence of any scientific mindset, I'm 99% sure you just did something wrong.
 

Offline Siwastaja

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Seemed like good idea to twist the wire strands tightly and place the kelvin wire connections with at least 20mm gap on the wire.
Without twisting and some gap between the kelvin wire connections the results were bit unstable, probably due to unstable connection and current distribution between wire strands.

Indeed, current sharing between the strands in stranded wires is a big question mark. People incorrectly assume the strands form low-resistance connections to each other everywhere within the wire, but this isn't true, there isn't enough pressure (if there was, then the wire would not be flexible anymore, the whole point of the stranded wire). Therefore how the strands are terminated at both ends is hugely important if one wants maximum possible current capability (and in this case, correct measurement result).
 

Offline Geoff-AU

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Must observe the 11th Commandment: "Thou shalt downscale all Chinese specifications by a factor of 2".

Nah, I decline your invitation to participate in the race to the bottom.

The end game for this starts at 10x spec inflation and ends at the moon (if not further).  60dBi antennas, 300dB car horns, 9000mAh 18650 cells… I’ve seen all of those for sale and you can keep em.  I’ll buy real specs from real vendors thanks.
 

Offline eTobeyTopic starter

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If you can't provide numbers and references there isn't really anything for anyone here to say.
It was never my intention to prove anything. There is also a question in my original post that can be answered.

I had another look, and the best i could find, that one supplier claimed it to be lapp cable (it wasnt), where i measured 80 strands of 0.28mm on which measurements via current confirmed that.
« Last Edit: May 01, 2024, 06:30:22 pm by eTobey »
"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 

Offline eTobeyTopic starter

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Given this glaring lack of scrutiny and total absence of any scientific mindset, I'm 99% sure you just did something wrong.
When two different methods give the same results, then an error is rather unlikely dont you think so?

Also when i do the same error on two different cables, why dont i get the same results on both cables?  ::)

I had another order of cables a few weeks ago, and just went for a shop with a website. I just realised, that they had an ebay account too, and this one was where i got scammed the last time.  :palm:
« Last Edit: May 01, 2024, 06:40:27 pm by eTobey »
"Sometimes, after talking with a person, you want to pet a dog, wave at a monkey, and take off your hat to an elephant." (Maxim Gorki)
 


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