Man dies after bathtub phone charger shock


#1

Originally published at: http://boingboing.net/2017/03/22/man-dies-after-bathtub-phone-c.html


#2

Just to be clear, it wasn’t the charger that delivered the shock. It was the extension cord plugged into the AC. Any appliance, or just the empty cord socket, would have produced the same result.


#3

This is a pretty tragic and pointless death. I am compelled to be snarky, after all it’s an idiotic thing that caused the death to happen… but trying not to be insensitive. Just don’t fuck with electricity mkaaay? Mkay.


#4

Trying to imagine a lawsuit in which apples attorney has to argue it was the extension cord, not the charger that caused the death…


#5

if the extension cord had been plugged into a GFCI outlet, he would’ve most likely survived. I think in the UK they call the equivalent device an “RCD”


#6

Sorry to hear this. Just don’t bring your electronics into the bathroom, period. And charging them there? Nope.

That tweet can wait Mr ‘President’


#7

This is the UK and things are rather different. I was nearly called as an expert witness in a vaguely similar case involving a hairdryer, but our H&SE know all about this stuff and it never even came to court.

The thing in a battery charger that could potentially be lethal is the input stage to the switched mode power supply. Nowadays, the full mains voltage is rectified to a capacitor and a DC/DC converter switches down the voltage to the output. In theory you could kill yourself if you managed to get a shock from the capacitor, at around 320 volts, but it would be rather difficult to do - the terminals are close together on the circuit board and there is an air gap on the board between the two sides of the switchmode transformer. (I dismantled an old one the other day to check precisely this point.) The rectifier means that even if you touch the prongs just after removing it from the wall, the back current will be tiny. Two rectifier diodes will need to fail at once.

In short:

  1. It is exceedingly difficult to kill yourself with a CE or UL approved charger, even if you immerse it in water.
  2. On the other hand extension sockets are not normally waterproof and contain exposed wiring, so if they are wet it is rather easy for a current to flow external to the extension socket.
  1. The trip current rating of an RCBO as used in the UK under current wiring regs is not sufficiently low to be sure of preventing cardiac fibrillation.

and
4. The case will be heard in England by a judge, not an easily influenced and scientifically illiterate jury. (Remember it was an English judge that skewered Apple in the Apple v Samsung case and threw it out, by pointing out that if Apple’s design was as unique and instantly recognised as they claimed, it would not be easy to confuse it with someone else’s product?)


#8

That’s why I use Connect-A-Cord to make sure my extension is long enough, but not so long that it will touch the water.


#9

In the US, only wet walls are required to have GFCIs. Is it the same in the UK (ie, running a cord from outside the bathroom would ensure that there was no GFCI) or are all outlets protected?


#10

I’m not sure how this works… or to be clear: I’m not getting a clear picture, because an electrocution hazard exists whenever you’re a more convenient path to ground (or substantially conductive enough to draw more than 20 ma -IIRC.) I can’t imagine a (proper, genuine Apple brand) charger delivering that through the wiring or the enclosure except in really bad luck circumstances. Was the extension cord itself plopped into the bath? Because the shortest most conductive route is from hot to neutral and ground. Separated (in murky bath water) by relatively little. Unless only the hot side got submerged (plausible) and current had no choice but to flow through the bath.

What I’m asking the EE geeks here is what was the likely configuration and mechanism? Because while I certainly wouldn’t try or recommend it, I was under the impression that being in water with exposed mains voltage depends a lot on where you are and the exposed current path.


#11

picks jaw up from floor

That they would sell small extension cords suggesting that you connect 50 of them together is fucking irresponsible. That’s a fire waiting to happen.


#12

Probably a good thing it’s a joke then. :slight_smile:


#13

No, in the UK bathrooms are forbidden to have anything but a shaver socket, which is a current limited socket. I’m not sure about wet walls (kitchens around sinks, utility rooms, and such), but bathrooms it’s forbidden.


#14

lol, yeah, good thing. :slight_smile: I’m a bit slow this morning and quick to get a rise; but it’s so believable with the idiotic things people will do with electricity.


#15

It sounds like the whole charger dropped into the water, which means the mains on the primary side was in the water. That’s a recipe for disaster no matter what’s plugged into it.


#16

Still…

…rested it on his chest while using the phone…

…something something Darwin Award.


#17

Rather I’d like to encourage the president to tweet from the bath, with an extension cord plugged in at the hall. You can greatly increase the greatness your tweeting this way. All those stories of danger - fake news and science…


#18

See the Wiring Regs. It’s mostly about distance between a potential live connection and an earthed object, intended to make it very difficult for someone to use themselves as a connection between one and the other.
Socket outlets are not permitted in bathrooms, but hard wires spurs are.


#19

In the incident here the man had the charger on his chest, so presumably something got wet and shorted to mains; effectively the most direct way to zap one’s self.

Besides that, just having things plugged in when wet is a terrible idea. Slight manufacturing defects can cause the isolation to be violated, and without a battery of tests that wouldn’t be detected, and far too often poor quality chargers will have no isolation at all. This will cause the charger to have one power rail be shorted to a rail on mains. This goes undetected by consumers for the most part because there is no path for current to flow, but when there’s conditions where there’s dielectric breakdown of the skin, the effects will be felt (usually in the form of sever electrocution).

Even fully isolated 5V is not a good thing to keep around wet skin. The resistance of water-logged skin can be as low as 2kΩ. 5V across that will give you 2.5mA, and while probably not lethal I for one would not like to have that going over my heart.


#20

Very few chargers other than for laptops would have a cord long enough to have a charge on your chest.

So -
maybe it was an extension cord?
maybe it was running off a lower voltage but was on his chest so he nailed himself in just the right spot?
maybe it was the switch and he nailed himself in just the right spot?

Not familar with UK bathrooms and am not an electrician. In general I am a little surprised that they use 240 when you have a higher likelyhood of a deadly incident when something goes wrong at that voltage, but maybe electrocutions are just really rare these days so there is no chance they will switch? Or other reasons to stick with 240?