Faulty power connectors

[Merlin3189]

I'm not sure what I'm asking here! I'm just astonished and wonder if anyone has similar experience or thoughts about it.
Out of a set of 15 power leads I have just tested, I found 4 faulty with a low resistance between the pins. They are about 3 years old, but show no signs of physical damage and have spent almost all their life as fixtures in a laptop storage cabinet.
When they are plugged in, the RCD protection trips, which is what drove me to testing them (after months of thinking the devices might be faulty.) A puzzling thing about this is that this tripping has been happening for about a year, but at the last PAT in April they were all passed and sport a current green sticker.
As they are molded on plugs (BS1363 male via 1m flex to IEC C5 female) I shan't know where exactly the fault is until I chop them up.
I've never known this fault before, though I suppose before RCD was common, it might have passed un-noticed.
Does anyone have any experience of similar?

 

[KrisBlueNZ]

I've had problems with power cables supplied with cheap Chinese laptop adapters. All that copper in those cables is expensive, you know, and they want to save every cent they can. So they supply cables that don't have enough strands and/or with strands that are too thin. And they also seem to have trouble making proper insulation. Bending a cable near the connector can cause the outer insulation to rip apart, and the individual wire insulation isn't any better. So don't twist the cable or it may go bang. Although the wire is so thin that it's not a very loud bang.

Of course it's a fire risk, but no one seems to care. Not down here, anyway.

 

[Merlin3189]

Having done some more work on these, it seems to me that the fault lies in the plastic used to mould the connector. Having removed all metal from it, I can put test leads into the vacant holes and get readings as low as 15kOhm - not exactly a conductor, but hardly an insulator. Since they were working at one time, presumably the plastic must change over time.

What amazes me is that safe & effective plugs have been made out of plastic for decades. People must have tried every conceivable suitable plastic by now, but someone is still trying different ones to find one which does NOT work!

HP, who supplied these leads, have now (26 August 2014) issued a voluntary return notice (which I've attached.) I'm a bit surprised it's taken them so long, as our first one went faulty over a year ago. I wonder if they were waiting for them to go out of warranty? Or for people to buy their own replacements, so that no one will claim?

 

[KrisBlueNZ]

Oh. I didn't try measuring the connectors on mine. I just cut them up and threw them away. But it doesn't surprise me. There is no corner that certain companies won't try to cut.

I'm actually surprised that there hasn't been more attention to this issue from interested groups like insurance companies and coroners. There was a case in Australia earlier this year where a women was electrocuted by a shoddy third party iSomething charger. I can only assume that people don't worry about obviously unsafe cables until they die, when it's too late, and when someone's house burns down, nobody wants to admit that they were using a dangerous cable, or they didn't know.

Interesting to see that HP/Compaq have been bitten by this problem. But I guess it hasn't caused any awareness of the larger general problem by anyone who can do anything about it.