Counterfeit power cords

[LongRunner]

I have an IEC320 C7 cord that claims to be made by both H.R.SILVINE and Kenic, but the plug doesn't look like either.

Cutting the plug off revealed a huge surprise - the wire strands seem to be copper-plated aluminium. Even the other counterfeits I looked at had copper wires. They aren't super-thin in this cord the way they are in some others, but still thinner than they should be.

By the way, the forum's a bit glitched-up right now.

[c_hegge]

Yeah, I've noticed that. I'm not sure exactly what's causing it, though.

[LongRunner]

After crunching the numbers, it turns out that the live and neutral wires in the second DHT cord have 24 times the resistance per unit length of 1.0mm² - and that's the better of my measurements.

What I'd like to see is something like this:

Before using an extension cord with this heater, get a qualified technician to test the cord to the current rating.

A curious dilemma is that IEC320 C5/C6 and C7/C8 couples, while only rated at 2.5A, are usually wired with 0.75mm², which means you can't test such a cord to the cable rating without severely overloading the connector.

[LongRunner]

And to add to the high-resistance brigade, another mysterious entrant. Its plug only has the rating "10A 250V" (yeah, right) faintly marked, the cable is marked with:

XD RVV WGX3C P.V.C WIRE B

And the socket is marked with "KKCK" on one surface and "KKS-10A" on the other. Resistance measures about 0.4Ω each on live and neutral and about 0.9Ω on earth; I haven't made an exact measurement, but it seems to be about 1.8m long. 0.1mm² or whereabouts? And yes, I ran the "sanity check" again.

[LongRunner]

And another one with the C7 socket, with both sides measuring 0.6Ω each. The plug only has the polarity markings and a "10A 250V~" rating, the cable reads:

FEILIPU ELECTRIC WIRE WORKS RVV 300/300V

And the socket is devoid of all markings, plus the contacts aren't as deeply recessed as they should be. The conductors are, again, way too small.

[RWenger]

If you can humor a novice, how you check a power cord? I am familiar with basic use of a multimeter, but what am I looking for?

[LongRunner]

Resistance of copper wire is approximately 0.034Ω per metre length for 0.5mm² (seldom-used), 0.023Ω per metre length for 0.75mm² (probably the most common metric size), 0.017Ω per metre length for 1.0mm², or 0.011Ω per metre length for 1.5mm². For American Wire Gauge, try 0.021Ω per metre length for 18AWG, 0.013Ω per metre length for 16AWG, and 0.008Ω per metre length for 14AWG. An ordinary meter will struggle to measure that low, but the contacts will add more resistance (potentially several times the cable's own). A high reading is indicative of either oxidised contacts or undersized wires. You will need to take 2 or 3 measurements, one for each conductor in the cord (active/live/hot, neutral, and earth/ground if applicable). Ideally, one test lead should have an alligator clip (clip to the plug pins) and the other should have a probe (insert into the socket holes). Note that there are some connectors that don't distinguish between live and neutral, so you may have to swap the probe over to the other side if you don't get a reading.

Of course, there are other indications of counterfeits, such as strange colour codes, wrong dimensions, shoddy materials, and a lack of certification marks (or marks on a connector that don't belong to any of the regions using it).

[LongRunner]

And to add to the high-resistance brigade, another mysterious entrant. Its plug only has the rating "10A 250V" (yeah, right) faintly marked, the cable is marked with:

XD RVV WGX3C P.V.C WIRE B

And the socket is marked with "KKCK" on one surface and "KKS-10A" on the other. Resistance measures about 0.4Ω each on live and neutral and about 0.9Ω on earth; I haven't made an exact measurement, but it seems to be about 1.8m long. 0.1mm² or whereabouts?

Just as I suspected, this cord blew up under a short circuit (which I boldly made on purpose — I wasn't foolish enough to attempt to use it).

The test setup consisted of a bog-standard 3m extension cord plugged into the outlet (on a C16 circuit breaker), with the counterfeit plugged into the XC's socket and…remember that chain of cords I ran that heater through? It turns out that the cord I fitted that socket (a white Clipsal 438) to is a bit too thin for the 438 to clamp onto tightly (it's a light-duty 0.75mm² type, though with a thicker sheath than some; besides, it's black), so I found an ordinary-duty white cord salvaged from a cheapo PC speaker set and attached the 438 to that. Anyway, for the experiment, I stripped the insulation from the former cord's brown and blue wires, twisted the conductors together, and inserted them into a "Eurostyle" terminal strip (those are insulated enough to protect fingers from making contact, so that's a start), then inserted the plug into the counterfeit's socket (which is much too loose). Switched on at the outlet and the counterfeit cord proceeded to melt through its insulation and sheathing, exposing wire strands . Subsequent autopsy revealed the earth wire to be about 24AWG (the other two are rather charred) — though even that is much larger than the resistance would have suggested . The rest of the setup is all but undamaged (save for a bit of what seems to be molten plastic deposited where the other cords mated with the counterfeit), though I should probably find something to do with that black cord (and a bunch of others — so feel free to sue me ) before anyone else finds it, plugs it in, and electrocutes themselves with the wires (I suppose clamping the conductors in separate parts of the strip would be a start).

So there you have it: If something connected to the mains with a counterfeit cord goes short-circuit and you're touching the counterfeit cord at the time, you're dead (if the circuit isn't protected by an RCD).

[LongRunner]

Another cord I think is worth mentioning: This one isn't underbuilt to all hell (the conductors are more-or-less the right size), but the plug was wired backwards. It also reads:

600V PVC INSULATED WIRE 18AWGX3C L.Y.

But given that it's a light-duty cord, I doubt it's a good idea to actually run it at 600V (not that I can think of a source of 600V, anyway). There are no markings on the plug or socket. With a correctly-wired replacement plug it would probably be usable, but I don't have one designed for light-duty cord so I'll just set it aside. Whatever I do with it in the future, I'll keep it to myself.

[LongRunner]

It stands for "Dura HexaTrans". The cord in question is fixed to a PowerShield PSG750 and looks normal in every respect. Fortunately, the knock-off's plug looks nothing like the real thing (left of photo), instead being somewhat closer in shape to a Burton plug (right of photo; the DHT fakes are new enough to have insulated pins, though); unfortunately for you, I don't currently have an intact DHT knock-off to take a picture of. Another strange thing about the DHT knock-offs is that the cable is labelled as "H03VVH2-F"; not only does the H2 designation indicate a flat cable, but the 2 seems to be subscript (looking much as I rendered it), which makes no sense. Not that counterfeits are ever OK, but I prefer the unconvincing ones to the accurate ones.