- #1
Guineafowl
- 762
- 366
http://www.telegraph.co.uk/news/2017/07/11/teenager-dies-charging-phone-bath/
The poor girl got electrocuted, I assume, from the USB case being live at mains voltage.
I don't understand - between you and the mains, there should be a transformer, class Y capacitor, and an optocoupler. No direct reference.
Now, you could argue it was a clone charger, with poor isolation. However, I can measure 135Vac (our supply is 240V) between my Apple charger USB plug's metal case and Earth ground. This, however, drops to 13V when I touch the case. I assume an Apple product is well isolated electrically.
The scope shows a 50Hz (our frequency) sine wave 400V p-p. Is this just coupling through the class Y capacitor? Do you think the girl's charger had an underrated cap that broke down when given a good reference to Earth ground? Is it OK for the manufacturer to supply lethal equipment with impugnity? She shouldn't have been using it in the bath, but anyone can get a good ground reference by leaning on a radiator or kitchen sink.
There's a frustrating lack of technical detail in the article, so I'd love to hear your take on the tragedy.
The poor girl got electrocuted, I assume, from the USB case being live at mains voltage.
I don't understand - between you and the mains, there should be a transformer, class Y capacitor, and an optocoupler. No direct reference.
Now, you could argue it was a clone charger, with poor isolation. However, I can measure 135Vac (our supply is 240V) between my Apple charger USB plug's metal case and Earth ground. This, however, drops to 13V when I touch the case. I assume an Apple product is well isolated electrically.
The scope shows a 50Hz (our frequency) sine wave 400V p-p. Is this just coupling through the class Y capacitor? Do you think the girl's charger had an underrated cap that broke down when given a good reference to Earth ground? Is it OK for the manufacturer to supply lethal equipment with impugnity? She shouldn't have been using it in the bath, but anyone can get a good ground reference by leaning on a radiator or kitchen sink.
There's a frustrating lack of technical detail in the article, so I'd love to hear your take on the tragedy.