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Counterfeit power cords

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Re: Counterfeit power cords

Postby Behemot » May 15th, 2017, 9:46 pm

Seems like whole new era is coming. After aluminium signal cables (now steel signal cables, as the steel does not break so much, so next time you'll wonder why your USB cable is piece of junk, check it with magnet), I've seen a report about aluminium power cords and extenders on our market.

It appears that aluminium is banned for flexible connections up to 16 square milimeters, I wonder which of these will have so thick wires :rofl:
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Re: Counterfeit power cords

Postby LongRunner » May 16th, 2017, 6:34 am

Indeed, I'm quite sure aluminium wire smaller than 16mm² is presently banned for any power wiring. And even when smaller aluminium wires were used (rather regrettably) for fixed wiring in a few countries (due to copper shortages), I don't believe they ever permitted it for flexible cords.
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Re: Counterfeit power cords

Postby Behemot » May 16th, 2017, 7:11 am

Aluminium is still OK for fixed wiring here, though mostly only very thick wiring is used in ground, connecting whole buildings and distribution points, nobody sane will use that in new buildings anyway.

But flexible cords? Oh my :frustrated:
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Re: Counterfeit power cords

Postby LongRunner » May 20th, 2017, 10:55 pm

Incidentally, I've found a "Category 5" lead with copper-clad steel conductors (while some coaxial cables legitimately have CCS cores, I'm not aware of this being allowed in twisted-pair cables used for Ethernet). (I had it laying around for a while but only just noticed, looking into the connector ends, that the cores didn't appear to be copper - upon which I found that it would stick to a magnet.) Not only that, but these are solid cores (as a patch lead, it should have stranded cores) and they're measurably smaller than even the 26AWG claimed on the outer sheath (which is already the bare minimum allowed - in copper - for Cat5).

I haven't tried plugging it in, but I have enough proper Cat. 5e patch leads (with stranded copper cores) to hand anyway, and it's too late to test this fake now.

EDIT 2018-04-02: I found another of these junkers, so might be able to test it at some time :D

EDIT 2, 2019-06-26: In tidying up the house, I threw it out. Nevermind :-/
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Re: Counterfeit power cords

Postby Behemot » May 20th, 2017, 11:03 pm

LOL.

I actually prefer solid wiring even for patch cords as it would take some effort to break coper wiring, and also 24AWG solid wire has the conductivity of aprox. 23AWG stranded wire.
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Re: Counterfeit power cords

Postby LongRunner » May 23rd, 2017, 7:40 am

Sure, the tensile strength of solid copper (or steel) wire is fine; it's fatigue from tight/repeated bending that weakens it. Solid-core Cat. 5(e) in the usual 24AWG has individual copper cores of about 0.5mm diameter; the flexible equivalent has 7 strands of about 0.2mm diameter (32AWG). That compares sensibly to common flexible mains cords (among others), which also have individual strands of typically 0.15–0.25mm diameter (or 34AWG through 30AWG) – just larger numbers of them, to make bigger overall conductors.

And I'm not sure what you meant this statement to be:
…and also 24AWG solid wire has the conductivity of aprox. 25AWG stranded wire.

A solid-core wire has the conductivity of a stranded wire the next size smaller? :huh: Well, given your stated preference, you most likely meant it the other way around, so I'll respond accordingly (though it's a technically valid reply either way):

When specifying multi-stranded conductors, the "nominal" cross-sectional area is that of all the strands combined – not that of the geometric circle enclosing them. So for 1mm² wire (for example), a solid core would have a diameter of ≈1.128mm (for most intents and purposes, 1.13mm is plenty precise), whereas a flexible equivalent might be made from (as per IEC standards) 32 strands, each 0.2mm (nominal) in diameter. While the enclosing circle for them is somewhat larger than 1.13mm, the effective conductor area happens to be well within 1% of the nominal (1.00531mm², to the nearest part per million).

Of course, not all arrangements will be quite this close – especially not the basic 7-strand sets (or even 3 strands in a triangle in some old cables) – but the principle remains. (In power cables made for fixed installation in structures, the strand size is often calculated from the desired area and a "convenient" number of strands, rather than the other way around; for example, 1.5mm² cable used in Australia for lighting circuits usually has 7 strands, each 0.522mm in diameter – or 522μm, if you want to be ultra-metric. Though manufacturers will sometimes "rationalise" a few near sizes into one to simplify the production processes, providing they remain within the permitted tolerances…)

By conclusion, having about the same cross-sectional area means the resistance is about the same, too (at least to DC, but usually well into the audio range if not higher). Stranded twisted-pair cables do have somewhat higher losses at RF than their solid-core counterparts, I'll give you that; but the usual plan for Ethernet installations is to keep the patch leads reasonably short (usually within 10m combined, or 5m at each end if they're equal), with the fixed (and concealed) cabling (which can, in most installations, be solid-core without a problem) going the rest of the way (the remaining 90m of the usual "100m" limit). As long as it's within specification (and the equipment at each end is up to specification), it should work fine; like any digital protocol, it either works correctly or doesn't…

EDIT: I have found that in 1.5mm² 7-strand cables, at least in Australia, the strand size has been rounded off to 0.50mm. This gives a true CSA for those of ≈1.374mm². The remainder of this post holds true.
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Re: Counterfeit power cords

Postby Behemot » May 23rd, 2017, 8:15 am

Yep, 24AWG solid is close to 23AWG stranded, gonna fix it…I've studied some materials in this subject and this is general conclusion. Remember that GbE works at 100 MHz, that's quite far from audio frequency :D

Ethernet however, or more precisely, TCP/IP, is quite robust and when it's bad, you get lower throughput. So ppl most usually don't notice their cabling sucks, it runs slower, but works. In case of UDP you loose packet, yes.
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Re: Counterfeit power cords

Postby LongRunner » January 8th, 2018, 3:59 pm

Yesterday, I put another of the DHT cords out of its misery, this time by loading it with a fan heater (the KFH660 I made a mini-review of, in fact); at 5A (1.2kW @ 240V) the DHT cord already got too hot to touch in a few minutes, and the full 10A (2.4kW @ 240V) was ample to bring the smoke out, melting and charring the whole cord until the conductors touched together in one place and blew open like a fuse - without even tripping the circuit breaker! (OK, it is a C16 MCB which is a bit more "forgiving" than the B-curve types predominantly used in Europe, but still…) Everything else seems fine, again.

Before the test, I measured the strands in that DHT cord to be 0.07mm diameter (to 0.01mm precision), and counted 21 of them which gives a total cross-sectional area for each conductor of 0.08mm². :omg: They may well be CCA too (it's hard to tell by looking at such thin strands, but they aren't too easy to twist together).
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Re: Counterfeit power cords

Postby Behemot » January 15th, 2018, 12:53 pm

Ain't that a bit thin? This's like rated for 10 A? :facepalm: :facepalm: :facepalm:
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Re: Counterfeit power cords

Postby LongRunner » January 16th, 2018, 9:40 am

If we didn't have to worry about fault current, then I might have charitably rated it for 2A.

To even sell something that dangerous (let alone using it) should be classed as attempted manslaughter, IMHO. :@
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