IEC leads, the wires just seem to get thinner and thinner

I remember a thread on here a couple of years back about under-rated cables used on IEC leads, unfortunately the situation seems to be getting worse rather than better.

Just received an IEC lead with a computer power supply, the lead in question is 1m long, and has a USA plug on one end, and a standard IEC socket on the other end. The socket is clearly marked 10a 250v. The cable is marked as 0.5mm squared. The entire 2 layer 3 core insulated cable is approximately 5mm thick, and has a measurement of about 0.5 ohms on each of the 3 wires from end to end (which gives about 1 ohm total resistance in the circuit).

Just looking at how thin the cable was, and the light weight of it alarmed me.

Compared with a 2m length of approved (Cable marked: FUJIKURA AS3181 LIC: 1025) 1.0mm square 3 core cable (approx 7.5 mm diameter) fitted with similar connections, you get less than .1 ohm per core using the same meter (fluke 87). (note that this is for 2m - not 1m - I didnt have a 1 metre length handy to do a comparison)

Considering that the thin cable was obviously intended for use in the US 120v market, and therefore the same type of appliance used there will be drawing DOUBLE the current of our 240v system, this makes matters even worse and a serious risk of fire if used on a 10a appliance.

Reply to
kreed
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"kreed"

** That was my thread, back in August 2002.

With heckling by " Miro " and generous assistance by Ross Herbert from WA.

** Whaaaaaaaaaattttttt ??????

You sure the resistance value is that high ?

** Sounds like the one I found - but much worse.

The wire inside that was not even copper, but a much higher resistance alloy !!

** 1 sq mm copper wire has only 17 or 18 milliohms per metre !!

That amount will handle 7.5 to 10 amps OK in a two conductor lead.

** Absoblooominglutely !!!!!

Care to check those resistance values again with more accuracy ?

Maybe use a 1 amp DC source ( bench PSU in current limit) and measure the voltage drop along the cable.

Was the supplier in Aussie ??

Please keep us informed.

...... Phil

Reply to
Phil Allison

SO you replaced it ?

Reply to
atec

I'd believe that.

madness.

cheap crap, probably made in China. I got a plug board in China recently; in addition to only having 5-6 strands of copper per cable (but very thick insulation - obviously plastic is cheaper than copper), the prongs on the 3-pin plug were about 0.7mm thinner than normal - so much that the plug falls out of ordinary wall sockets. like hell its

10A. I havent measured the resistance, as its not here right now...

And a mate who runs a company in China making thumbprint scanners asked me to look at some plug-packs they had been having trouble with. I hacksawed one apart, and found some really interesting stuff. Like the switching transistor nut (no spring washer) was loose, the soldering was appalling, and the construction was such that the P,N wires wrapped around the switching transistor and 3-leg-gapped flyback transformer. Small wonder they were dying, and like hell it passed CE - they just printed up a label that said it did. Be afraid, be very afraid.

AIUI DSE has had some problems in the past with allegedly EMC compliant gear not actually complying; apparently they now put all of their products thru compliance testing in Aussie/NZ testing labs.

companies that import direct from China really need to verify that they are getting what they ask for, and that it *actually* meets the relevant standards.

Whats even scarier is going to a place like Saige (sp?) in Shenzhen, huge components/computers place - 3 Floors of electronics components, another 6 or so of computer stuff. Where I saw people recycling ICs - straightening leads, cleaning with erasers, putting into tubes, all sans antistatic precautions. And where the aforementioned plug-packs were sourced. I wonder how many AU/NZ parts suppliers shop there?

Cheers Terry

Reply to
Terry Given

I noticed the same thing with a cheap set of automotive jumper leads, really thick insulation but about 1mm square cross section conductor. Not only that but the bulldog clips had high resistance crimp connections and the whole think would get too hot to touch if you put any sort of a load on it.

Friday

Reply to
Friday

Although this is related to a US style cordset this is a serious issue that is becoming more prevalent. As China uses the same domestic outlet style as AU/NZ there are more cords being sourced and supplied from there that do not meet the basic AU/NZ standards for the cordset and mains plug. There is also no understanding about light, ordinary or heavy duty ratings or about the hot condition ratings for the connectors.

I would guess the 10A rating you refer to is stamped or embossed on the plug face and not the cord, which is very common. Looking inside many of the generic ATX computer cases that are fitted with PSUs will often yeild one of these unapproved (and unapprovable) cordsets (in a bag) which are intended for Chinese domestic consumption.

Reply to
Dave

"Dave" ??? Not Dave Castels ????

** No IEC lead can be LEGALLY sold or supplied in Aussie without receiving type approval.

Approved leads must use a 3 core cable with at least 0.75 sq mm copper conductors.

Such a lead runs comfortably at 7.5 amps and a tad warm at 10 amps.

So, despite there being a variety of conductor gauges, no lead is dangerous in use.

** The only meaningful markings are the APPROVAL code numbers which must be marked on each plug and the cable.

These numbers start with letters indicating the Australian state where type approval was obtained, ie V = Victoria, N = NSW, Q = Queensland etc.

** I really doubt the Chinese are so utterly reckless as to consider such leads as mentioned by the OP legal trade there.

The Chinese " love their children too " - you know.

....... Phil

Reply to
Phil Allison

Try pulling some of these 500 watt psu apart , 5v rails on .6 mm wire.

Reply to
atec

Best I've seen was an appliance from India (sensor system base station) , they used 22 gauge for the internal 240V wiring (had a current draw 1A). Had crimped spade lugs for some terminations , soldering for others. All internal wiring was the same colour.

The aluminium front panel provided the connection between the frame , case and ground.

The power supply was a modified computer psu with the iec socket removed from the power supply and directly wired to the iec socket on the back of the case.

The soldering on the psu was very bad and there was no grommet on where the wires came through the case.

Amazing thing was when stuck on an appliance tester it withstood 500V 25A and passed the earth tests.

Alex

Reply to
Alex Gibson

After the silly shitfight that happened over this in 2002 mostly by people who didnt seem to know - (and worse still didnt want to know) - the basic laws of physics or ohms law, I Decided to do a "real world" test on the cable, using a "Bi-Lo" electric Jug. The jug was labelled at 2400w @ 240v), however measurement of the element resistance at room temperature showed 27.5 ohm and the mains voltage used was 237.5v so this would mean that the jug was drawing 8.64 A from the mains. (The measured current was actually 8.63a)

A fluke 87 meter was used for the measurements shown

Firstly tried measuring the voltage drop along the 2m length of approved IEC cord mentioned in the original post. This showed a voltage drop of 0.52v across each conductor when the jug was turned on from cold. This indicated a cable resistance of approx. 30 milliohm per metre. (including the resistance of the connectors molded onto the cord). (I suppose we can assume an approximate 12 milliohm loss in the plug, socket etc in the circuit from this ?)

With the jug again at room temperature the suspect cable was then connected in the circuit. This showed an alarming 5.3v (note 5.3v not

0.53v) drop along each core of the 1m lead when the jug was switched on from cold. According to my calculations, this shows a cold resistance of the cable assembly of around 0.61 ohm (about 0.49 ohm if we take the connector losses mentioned above into account ?)

Within 30 seconds, the cable was getting quite warm, and within a minute, small amounts of smoke were noticed. The mains power was shut off immediately, and the water in the jug was nowhere near boiling point.

I stripped back about 1.5 inch of outer insulation from the cable, so as to look at the state of the internal conductors, they were all black in colour, and looking at the copper internal of one of the wires, it looked like copper to me, and it readily took solder when I tried it. However it was thinner even than than the normal grey cheap & nasty figure "speaker wire" that is often sold at major electronic retailers.

I let everything cool down, and tried again, the meter was connected in parallel with one core of the cable in order to measure the voltage drop in real time. The jug was then switched on and the meter again read 5.3v. it took a couple of minutes for the jug to start to reach boiling point, and in that time the voltage loss steadily rose from 5.3 v to 5.58 v The cable began to smoke and melt, and I observed the insulation on the exposed inner wires beginning to melt and stick to the others, I turned off the power as I had no desire to short circuit the workshop supply. One part of the cable had sat in a circle over itself, and sat over another part of the cable, these 2 parts had softened sufficiently to stick themselves together quite well

The bodgy cable was labelled "3 x 0.5mm sq"

Remembering that this test was at 8.6a, and not the full 10a, it would have been a lot worse if the cord was used on a 10amp appliance, or on a 10a electric jug in an area where the mains was around 250-260v (which does happen)

The same test done (from cold to boiling) with the "real" 1.0mm sq lead showed no significant cable warming.

Came from Australian Ebay seller, it was a PC based commercial arcade (video game) board system. It included a standard "off the shelf" 300w ATX supply, and this dodgy IEC cable.

Reply to
kreed

** The scenario you describe here is close to IDENTICAL to that with the IEC cable I saw back in 2002 - maybe even a tad worse.

With around 300 milliohms pre metre of conductor - the equivalent copper cross-section is only * 0.06 sq mm * or 13 times less than the minimum required by law !!!!!!

Gotta be the same high resistance ( bronze wire ? ) alloy I saw.

Must be a lot of these horrors floating about, packed in with Chinese electronic items.

BTW:

I just checked out the IEC lead that came with my DSE Q1803 CRO - no problems, had all the right markings and passed the "jug test" easily.

Responsible importers ARE aware of their legal obligations re IEC appliance leads and simply REMOVE any non-approved ones and replace them in the packing.

....... Phil

Reply to
Phil Allison

"Alex Gibson"

( snip silly whinge)

** Yawn - that is not a life threatening hazard to anyone.

An IEC lead with high resistance wire in it damn well IS !!!!

No mater what it was originally sold with, an IEC type general purpose appliance lead can and will be transferred to another appliance, at some or other, time that draws 10 amps of AC current.

The unsuspecting owner of the illegal ones will then have either a fire on their hands or else a very serious electrocution hazard.

If the culprits supplying such illegal IEC leads can be identified and located, the relevant state government energy safety authority will ( once informed ) act very promptly to stop them and or prosecute them.

Ross Herbert and myself have found the state authorities take a VERY SERIOUS view of this kind of public safety offence.

I bet the courts will too.

...... Phil

Reply to
Phil Allison

That's very high, I get 0.6 ohms for about 10m of 24AWG telephone wire.

Bye. Jasen

Reply to
jasen

10m of 24AWG telephone wire.

it is, but 10m of telephone wire might at least stand a better chance of dissipating the heat over a 10m length than this crap "mains cable"

Reply to
kreed

No.

Sorry, maybe I didn't explain it well enough. Often the plugs have the voltage and current rating embossed into the plug-face, and for approved types the approval number will be too. So the 10A rating may be for the plug but not the cord. The plug molder and the cord maker will usually not be the same factory, and neither of them will have much of an idea about the true parameters of the products as they will have copied it from someone else anyway. The problem gets worse as maker(x) copied maker(3) who copied maker(2) who copied maker(1) who was an OEM contract maker.

The chinese domestic market plugs look the same as AU/NZ ones but there is no approval marking. The Chinese ones are also appearing with insulated pins although they are not required in China. These are just as DANGEROUS as the under-rated cords because the insulated pins snap off in the socket, leaving exposed metallic parts.

It all comes down to lack of knowledge rather than intent. The cords mentioned above are indeed sold within China in large numbers quite legally. For an ITE device such as a PC the cord will not cause a problem due to overheating. As pointed out in another post (by you I think) the problem arises when the cord finds its way elsewhere. No doubt time will tell that this is a problem over there and as the marketplace matures they will put better regulations put in place.

Reply to
Dave

"Dave the Context Snipper from Hell

** No - you were just plain wrong.

Approved leads must use a 3 core cable with at least 0.75 sq mm copper conductors.

Such a lead runs comfortably at 7.5 amps and a tad warm at 10 amps.

So, despite there being a variety of conductor gauges, no lead is dangerous in use.

** That is COMPLETELY ASININE CRAP !!!

Smacks APPALLINGLY of RACISM too.

** Bollocks.

** I really doubt the Chinese are so utterly reckless as to consider such leads as mentioned by the OP legal trade there.

The Chinese " love their children too " - you know.

Not matter what some anonymous fuckheads like " Dave " will have you believe .

....... Phil

Reply to
Phil Allison

It comes down to price, I have a mate who sells these things in Europe. He used to have a small factory where he made cables, now he buys container loads from China. The whole assembly costs less than he can buy one of the plugs for, parts, labour, shipping and duty included. Somewhere corners have to be being cut, but, as he says, he would have no market for the home grown ones, they cost a dollar more.

Well I dont think that is quite true, I saw a one metre IEC cable in a pommy Hi Fi mag, it was 450 pounds Sterling. However the review reckonned it was worth it, as it gave a much more fluid sound and an expanded sound stage whatever that means.

Keith

Reply to
KeithR

Well I only bother including thr bits relevant to the discussion, the rest I agreed with or had no comment on.

Since you kept this bit in I assume you believe it is significant. Two core leads are OK providing they are not attached to three position connectors... yes I am sure you know that but there are others who don't.

dangerous

Your left the word APPROVED out. In which case I agree, except for counterfeit products.

consumption.

I'll leave all this in. Since your shouting it I guess it has to be important..

Of course the Chinese love their kids too... and although I know precisiely what you mean by it, ignorance or plain lack of knowing better, kills plenty of people every day in all kinds of fields. As for me being racist, I showed this to one of our chinese engineers today and asked him... he doesn't think so.... and as for my comment (> > It all comes down to lack of knowledge rather than intent.) as he put it "they don't know what they don't know" and of course neither do any of us if you look at it logically.

Unfortunately the case just isn't that simple. In Au we have a minimum conductor size (as you pointed out previously) which effectively outlaws the sale of light duty cords fitted with certain types of connectors (such as IEC60320 Type C.13). However although China does require certification of cords they have a much less restrictive definition. See

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Experience is what led to the declaring definition being worded the way it is here. As the CCC scheme matures further these sorts of issues may get included. UL have a similar approach to AU in that they have additional criteria they apply during type certification.

I will add this last bit below simply because I find it very important to counter what you inferred... the inference being that because the Chinese love their kids they wouldn't do anything to endanger them.

A large part of my business involves correcting similar assumptions. Specifically companies go to the various trade shows and buy product on the basis that it must be OK otherwise the vendor wouldn't be able or allowed to sell it. This assumption costs AU importers millions of dollars per year - looking through

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will give an idea of what happens to a variety of products which are imported and sold based on assumptions the factory must know what they are doing. What appears on the recall site is but a fraction of what is recalled/reworked/repaired for reasons other than saftey issues.

I really think you have got the right idea sometimes Phil and some of the stuff you post is sensible and has history to back it up. Normally I wouldn't even bother replying to a circular argument but if there are people thnking about importing stuff from anywhere using an assumption "it'll be alright because the factory says it is", and because "they already sell lots elsewhere", the buyers needs to ensure they have a decent product assessment program to verify all is indeed OK.

I am only anon in here to avoid our servers getting bombed by spam. If anyone wants to contact me I am happy to help, all they have to do is ask and I'll provide a working ISP based email address.

Reply to
Dave

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