Beware of dodgy instrument cables

[DaJMasta]

By chance, I connected up my preheater to try taking some video with the new thermal camera, and I just used an instrument cable that was sitting around - looked and felt normal.  I powered the thing on and within seconds, the hottest thing was the wire... now I know the preheater has a really high thermal mass, so i figured it would just take a second to become more prominent.... but it didn't.

I shut the thing off at close to 90C reported from the cable, where the insulation had visibly gone slack from the heat and a very slight smell in the air - the total time was maybe a minute and a half.  No UL listing or comparable on the plugs, and to my surprise, no gauge reported on the jacket of the cable, though it claims 10A 250VAC  .  Each conductor measures about an ohm on a 2m cable (so 2 ohms for the full path....), and twisting the tiny, tiny strands together gets to be about as thick as a 26AWG solid core (and probably less capable).


Be careful with the instrument cables you use on high current devices.  This was an accident waiting to happen and I happened to be watching closely when I eventually used it in a high current situation.  No idea where it originally came from, it's been in the box with plenty of others for years.

[gibbled]

I scrapped a similar cable a couple of years ago, turned out the (thin) conductors were copper clad aluminum.  The copper cladding was blackened in places from the temperatures it reached.

[Cubdriver]

    Wow!  It's a damned good thing you were keeping an eye on it - that could have gotten VERY ugly had it been unattended.  I'm sure thousands of similar cables work adequately for things with low current draws and thereby go unnoticed, but as soon as you try to load it, buh-bye.  It's a shame that you can't even trust friggin' power cords any more.  Sheesh!  Scumbags will cut corners and/or counterfeit ANYTHING!

-Pat

[Electro Detective]

John Ward has some good videos where he gives these cables a good thrashing 

[ConKbot]

You misunderstood!  The C13 connector is rated for 10A, no promises about the cord. 

[Electro Detective]

..and twisting the tiny, tiny strands together gets to be about as thick as a 26AWG solid core (and probably less capable).

I just realised that's typical microphone cable AWG isn't it ? 

Great for millivolts, no good for the kettle !   

[DaJMasta]

I use it as my go-to breadboard hookup wire for, I think wire wrap wire is around 28 and my mod wire is 30 AWG.  I'd be hesitant to put an amp through 26AWG stranded, though it should be fine 


Nicely smoked cable in that video, mine did actually connect the ground pins and is probably made with copper, though, so I think this may be a very slight step up.

[Halcyon]

Judging by the title, I thought you were talking about dodgy XLR cables (which there are many of). But yes, dodgy IEC/appliance leads are probably worse.

It's almost impossible to tell these days, even with cables bundled with reputable appliances. I've personally kept a box full of thick IEC leads from the 1990's (when leads were good), or I order "known good" leads. Sure, they might not have insulated pins, but so what? Chances are, they are much safer than the won-hung-lo leads shipping with consumer devices these days, which go straight into the bin.

[Zucca]

happened to me too... made in china.

[Ampera]

Yeah, don't use those cheap guitar cables. They just break all the time.

[wraper]

Few years ago, after reading about such cables, I measured resistance of all cables I had. And found one of such, cut it and there were super thin CCA strands. Since then I always measure resistance of the cables I buy. Then last year I bought 2 cables in local electronics shop and they turned out being counterfeit crap as well.

[Electro Detective]

Yeah, don't use those cheap guitar cables. They just break all the time.

They fail as clothes lines too 

Dumpster Dive Cat 5 cable is the way to go   

[wasyoungonce]

So that's what the issue is with some cables I got from fleabay China.   I found them really thin.  I cut one open found the wire way to thin...wouldn't solder etc...tossed them all thought nothing else.  This explains it.

Jeez China has a long way to go.

[Electro Detective]

So that's what the issue is with some cables I got from fleabay China.   I found them really thin.  I cut one open found the wire way to thin...wouldn't solder etc...tossed them all thought nothing else.  This explains it.

Jeez China has a long way to go.

These product dumps on our shores are so dodgy that even the Dodgy Brothers can't compete and gone out of business   

Cheapest Export 'CE' quality to die for   

[Shock]

These are called "power cables" not instrument cables.

If you want some really good ones talk to the guys at the local pc store, they might have a few server or high end power supply cables spare. The high current ones are thick and noticeably heavier and harder to flex (as well as having the rating on the cable). I've had a lifetime supply since the 80s.

Never buy Chinese sold power cables and avoid buying them online unless it comes with a nice piece of gear. I've even found some to have been incorrectly wired. Some Chinese do not realize that US 120V and AUS 240V 3 pin polarized mains plugs look similar but are more like a mirror image of each other, so the most common mistake is live/hot and neutral flipped. But there can be earth pins present and not connected and all sorts of crazy shit. Either that or they are hawking off rejects.

[Red Squirrel]

That's scary, I've always been naive and assumed they all used half decent gauge wire like at least #16 with some using #14.   Should probably check my server rack for any cords that are warm...  I guess if it has not caused a fire after all these years I should be good.

[Electro Detective]

Golden Rule for suss POWER cable made in OS sweat shoppe:   

                                                               "If it's TOO thin, it goes in the bin"      

[PChi]

It's difficult to tell from the outside that a power cable has undersized conductors. The economics of manufacturing them seems a little suspect. They are using more plastic to save on the copper. Also the copper can look funny and I guess is badly recycled so I presume will have somewhat higher resistivity.

[RoGeorge]

That's scary, I've always been naive and assumed they all used half decent gauge wire

Same here. I was not aware that the wires can be THAT bad, but they still write 10A on the plug.
Thanks for the warning.

[SeanB]

You also get a cable with a 3 pin plug and socket on the ends, that is made from that funny brass looking steel mystery metal used in them, but where the only metal in the wire is some strands of thin something wire in 2 of the cores, blue and brown, with the green/yellow core just being a dummy filler in there.

I keep those cables in a special box, which goes to the scrapyard when full of them, assorted copper and other cables. I get 20c per kilo for this, a lot better than simply dumping it in the skip to leach out whatever the metal and plastic was, and it goes back to the Great Wall to be recycled again.

[zl2wrw]

One of my co-workers ordered some LED lights (complete with mains-powered SMPS drivers) direct from China, and the IEC-type power cables included with them were rather dodgy:


Mystery metal conductors, high resistance (compared to copper), and the conductor strands could be described as "springy", although they were non-ferrous as they would not stick to a magnet. Of course they failed the electric kettle test

I wonder how many fires have been caused by "overloading" these cables?