So some kid was shocked and almost died after putting the end of a USB cable in its mouth. The USB cable was plugged into a laptop which was plugged into the wall. See here http://www.9news.com/news/article.aspx?storyid=130287&catid=339 the ONLY way I could see something like this happening, is if somehow the ground pin on the receptacle was energized (for example bootleg ground and loose neutral somewhere, something like that). Instead (according to the news) theyre inspecting the USB cable :roll:
kid shocked by USB? I dont think so.....
- Thread starter wireguru
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sawdust454
Member
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- Stuarts Draft, Va
I dont see that happening either. Usb is 5volts dc and limited current. There has to be more to this story.
I dont see that happening either. Usb is 5volts dc and limited current. There has to be more to this story.
I still think the ground was energized. The shell of the USB plug is going to have continuity through the laptop, charger, and power cord to the ground pin of the receptacle its plugged into. The article said the outside (shell) of the USB plug had skin melted to it.
kwired
Electron manager
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- NE Nebraska
every laptop i have seen has external power supply usually around 19 VDC.
unless there is a common between primary and secondary of power supply it should be isolated, the shell of the usb cable could possibly be connected to equipment ground on another connected device like a printer and that could be a source for the incident mentioned,
unless there is a common between primary and secondary of power supply it should be isolated, the shell of the usb cable could possibly be connected to equipment ground on another connected device like a printer and that could be a source for the incident mentioned,
Usually the DC ground on the laptop supply is connected to the ground pin on the laptop supply's line cord.
LarryFine
Master Electrician Electric Contractor Richmond VA
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- Henrico County, VA
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- Electrical Contractor
It sounds like the receptacle the power supply was plugged into needs to be inspected.
ELA
Senior Member
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- Electrical Test Engineer
Every put a 9V battery on your tongue :grin:
We used to do this as youngsters and that hurt. Of course w would pull the battery out of our mouth right away.
The mouth area could be pretty low resistance. It would only take 1000 ohms for 5ma to flow at 5V.
I could see this type of shock as being very uncomfortable but I am not sure how the 3rd degree burns happened unless there was a power supply fault.
If the cord were left in the mouth for a long enough time maybe??
We used to do this as youngsters and that hurt. Of course w would pull the battery out of our mouth right away.
The mouth area could be pretty low resistance. It would only take 1000 ohms for 5ma to flow at 5V.
I could see this type of shock as being very uncomfortable but I am not sure how the 3rd degree burns happened unless there was a power supply fault.
If the cord were left in the mouth for a long enough time maybe??
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
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- Electrical Contractor
I believe it takes a lot less current to clamp the heart than it takes to cause tissue damage.
ohmhead
Senior Member
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- ORLANDO FLA
Well read this on current that can be via USBhttp://pinouts.ru/Slots/USB_pinout.shtml 5 volts but 1.8 amps
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Medically speaking one joule is enough to cause fibrillation.
1 watt = 1 joule per second
I don't know what the limits of that USB would have been, or any other for that matter.
A Defibrillator is capable of being manually set down to one or two Joules. A Child's body is smaller that adults and typically have a lot less internal resistance, thereby taking less energy to get the heart.
However, I am skeptical that just the USB caused it, without other mitigating circumstances
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