USB Charger electrocution

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Hi All,

No doubt you have all read or heard about this recent story;

http://tinyurl.com/llkx7dw

It seems to me a lot of double-insulation has to fail, in both the
USB-Charger and in the laptop headphones and laptop charger, to
produce the electrocution, which seems rather improbable to me.

I'm not doubting the fact of the electrocution, just the alleged
method. No one has mentioned a nearby lightning strike, but that seems
more likely than the proposed mechanism.

Or am I missing something obvious?

Ross


Re: USB Charger electrocution
On 28/06/2014 1:49 PM, RMD wrote:
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I agree. I was not aware of a lightning strike though.
When I first heard of it I imagined headphones connected to a grounded  
class 1 system and a fault in the class 2 USB charger.

Tony



Re: USB Charger electrocution
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You left the class 3 police and class 4 journalists out of the equation -  
there's a lot of stupidity in this world, and it seems to be concentrated  
among those who're supposedly credible :-(

I know of precisely zero laptops which can be charged from a USB charger -  
they all need in excess of 15V (even "netbooks" need at least 12V) at  
several amps, whereas even the most powerful USB chargers can barely muster  
2A and never above 5V.

If the "USB charger" was in fact a device which plugged into her laptop's  
USB port and provided power to yet another device, how the f*** did she  
manage to get electrocuted by 5VDC?

Based on what I've seen on assorted web sites, I'm more inclined to think  
that she was having a bath with her laptop by her side, likely on webcam  
with someone, when the laptop and charger both fell into the tub.

--  
Bob Milutinovic
Cognicom



Re: USB Charger electrocution

"RMD"
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** The only device that has been claimed to be faulty is the USB charger  
used with the phone. Most laptops are earthed to the AC safety ground when  
charging, which seems the only way the victim could have completed a circuit  
to ground if she had hold of some metal part of it.


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** Yep  -  my first thought was that the alleged burn injuries were more  
likely from lightning.


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** Wait for the Coroner's report  -  cos that will contain actual facts.


...   Phil




Re: USB Charger electrocution
On Sat, 28 Jun 2014 05:49:22 +0000, RMD wrote:

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What double insulation?


Re: USB Charger electrocution

"news13"
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** You being funny or you have no idea what "double insulation" means ?



...  Phil



Re: USB Charger electrocution
On Sun, 29 Jun 2014 14:14:34 +1000, Phil Allison wrote:

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My understanding was that they didn't meet Aussie standard and thus were  
not double insulated.

Re: USB Charger electrocution

"news13"
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** So Australia has the only "double insulated" electrical appliances in the  
world ?

FYI:

Australian electrical standards are closely derived from similar IEC  
standards.

Almost every country in the world is a member (or affiliate) of the IEC  -  
including China.

http://en.wikipedia.org/wiki/International_Electrotechnical_Commission

If a manufacturer builds an item to meet double insulation requirements,  
they can use the double square symbol  -  no outside certification is  
required for that.

However, items like USB chargers fall into special category (called  
prescribed items) where agency certification and labelling to the relevant  
Australian standard is legally essential in order to go on sale here.

For items made in China, such certification can be done by locally and is  
normally little more than a formality -  assuming that the design meets  
international standards.



....  Phil














Re: USB Charger electrocution
On 29/06/2014 2:39 PM, news13 wrote:
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Double insulated means just what it says. The low voltage side must be  
separated from the high voltage side by two insulators, each of which  
is, on its own, capable of resisting the mains voltage.

Sylvia.

Re: USB Charger electrocution

"Sylvia Else"
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** Fraid that is not the case in reality.

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** However the rules for class II appliances are not so pedantic.

A single layer of a specified material and thickness may be sufficient as  
long as it is not subject to deterioration in use, or a gap on a PCB between  
live conductors and user accessible metal few mm wide, or the live and  
accessible metal parts are bridged only by a class Y capacitor of approved  
design and low enough value.

Double Insulation sounded like a brilliant idea once -  but has been  
gradually whittled down and compromised in so many ways that it is now real  
worry considering you have to trust notoriously dodgy Chinese manufacturing  
culture to get it right all the time, or you could die.



....  Phil










Re: USB Charger electrocution
On 29/06/2014 4:38 PM, Phil Allison wrote:
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A youtube video exists that determines that the high voltage side of one  
of these cheap Chinese chargers is isolated from the low voltage side by  
a thickness of .25mm between two soldered joints.

That is clearly not just a case of dodgey manufacturing, but really bad  
engineering in the first place.

I've got one of those $1 chargers mentioned before headed my way, not  
for use obviously, but for inspection.





Re: USB Charger electrocution
Clocky wrote:
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Got two of those, one physically blew the usb plug clean out of the  
socket when I was not looking.
http://i60.tinypic.com/14mb4m9.jpg">


Re: USB Charger electrocution
On 9/07/2014 6:31 AM, F Murtz wrote:
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That's nasty and you're lucky you weren't hanging onto it, or the phone.  
Don't use the other one, rip it apart and see how close the mains input  
is to the output.

Unfortunately it's not only chargers that end up burning. I bought one  
of those little wireless keyboards that come with a USB dongle.

I used it for months without issue, then one day I was using it and the  
keyboard suddenly stopped working. I thought the keyboard needed  
charging, but then I noticed a burning plastic smell.

It was the dongle, it was so hot that it had turned it's housing into a  
Dali.

Lucky there was no permanent damage to the PC.

Re: USB Charger electrocution

"Clocky"
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** If that is the video by Dave Jones, then it is irrelevant to my point.


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** It is clearly a case of criminal fraud by the Chinese makers and the HK  
based dealers on ebay etc.

Got nothing to do with the millions of supplies that come with new equipment  
and are sold by regular importers.


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** Cheap thrills  - eh ?


....   Phil



Re: USB Charger electrocution
On 9/07/2014 9:24 AM, Phil Allison wrote:
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It's not the video by Dave Jones which I have also seen. He too noticed  
the poor isolation between mains and output IIRC so it's relevant to my  
point.

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I don't think they deliberately set out to kill people, but clearly poor  
design and manufacture is having that effect.

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Nobody said it did.

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Not as cheap as one of your rants ;-)


Re: USB Charger electrocution

"Clocky"
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** Shame your point has nothing to do with the para you posted under.


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** Nobody said they did  -  fraud is not connected to murder.

     So another total irrelevance.


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** By posting your drivel where you did, you made that implication.

    With any luck, your $1 Chink time bomb will kill you.


....  Phil



Re: USB Charger electrocution
On 9/07/2014 2:53 PM, Phil Allison wrote:
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I said they didn't, nobody said they did.

   fraud is not connected to murder.
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I didn't say it was, and it wouldn't be murder in any case.

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Much like most of your posts.

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I certainly did not, you just made your usual assumptions based in your  
incomprehension.

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Unlike you Phil, I know what I'm doing.




Re: USB Charger electrocution
On 28/06/2014 3:49 PM, RMD wrote:
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In a properly designed and constructed charger, that's true.

Some of the USB chargers that can be bought from China are not properly  
designed, and electrocution is not especially unlikely.

Sylvia.


Re: USB Charger electrocution
RMD wrote:

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Sounds very similar to this one year old news.

http://tinyurl.com/qzmmglj


Re: USB Charger electrocution
On 1/07/2014 4:39 AM, asdf wrote:
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It makes me wonder how many electric shocks, burned out chargers and  
fires have actually happened and never been reported. It's only the  
extreme cases that make the headlines. If you get shocked by a device  
you are using every day, wouldn't you report it to consumer protection  
(1300 30 40 54) ?

Funny how this thread got killed and another one opened.

Tony


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