Author Topic: Why some people died in their bath after smartphone dropped into water ?  (Read 14122 times)

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Offline KL27x

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #25 on: January 30, 2020, 08:08:31 am »
Quote
There are countless youtube videos, search bigclivedotcom to start.
So I did some searches, and the only thing I found was (easily, anyway) was a bigclive's thing with the disco camping light. I actually watched that before and from memory, it was indeed something like mains in a charger output or something.

So I bet the wrong horse, and I stand corrected.

I would still like to see even one investigation which shows this was the case in any of these phone charging deaths, rather than user error of mains electricity/extension cords.

FTR, I wouldn't trust any untested/unknown charger in the bathtub. Even if it was from Apple. I'm just curious if this is a major public safety thing, or if user-error is the main problem. Afterall, we have GFI outlets for a reason which existed even before cell phones... I guess it musta been mostly hair dryers and again, user-error. Not that a single or even just a theoretical death from a crappy charger being properly (properly, so long as we know what we're doing, other than we trusted the wrong charger) used in the bathtub isn't horrible.
« Last Edit: January 30, 2020, 08:22:21 am by KL27x »
 

Offline Jwillis

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #26 on: January 30, 2020, 11:07:19 am »
This is all that came up when I searched for person killed in bath tube with cell phone were 4 cases world wide.
 https://www.cnn.com/2017/07/18/health/teen-bathtub-electrocuted-text-trnd/index.html .https://www.msn.com/en-nz/news/world/russian-accountant-26-is-killed-instantly-after-dropping-her-phone-into-the-bath-while-it-was-charging/ar-AAHuAkD ,
https://www.bbc.com/news/uk-39307418 , https://nypost.com/2018/01/02/pregnant-woman-electrocuted-to-death-in-bathtub-while-charging-phone/

The incidents state such things as extension cords  plugged into non-GFCI, non-grounded receptacles. One clearly stated the extension cord was plugged  in a hall way receptacle.
 

Offline Brumby

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #27 on: January 30, 2020, 12:41:44 pm »
FTR, I wouldn't trust any untested/unknown charger in the bathtub.

FTFY
 

Offline james_s

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #28 on: January 30, 2020, 06:36:23 pm »
I think theirs more to these stories than what is really being told. The average USB charger cable is around 3 feet long or about a metre. Electrical code states that any power outlet must be a minimum of 6 feet or 2 meters from the bathtub or shower or toilet . So as the OP stated it's quite likely that an extension cord was used at the time of insistent . GFCI receptacles are supposed to be installed in bathrooms but I have seen these plugs replaced with standard wall receptacles.
So in a scenario of no GFCI with an extension cord charging a smart phone while taking a bath add up to a very bad day for the victim.
Darwin wins again.


Longer USB cords are widely available, and extension cords are not inherently unsafe. I still would not use any device plugged into the wall in any form while in the bath but common sense is not so common.
 
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Offline nigelwright7557

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #29 on: January 30, 2020, 07:52:29 pm »
- The charger having an isolation fault which means the charger's outputs are at full line voltage relative to ground, and thus the phone's electronics. Dropping the phone in the water is thus equivalent to dropping the mains cord in the water. In fact you don't even need to drop the phone in the water if it has a non-insulated metal chassis....

Important thing to note here: this only poses an issue when the bath's metal fittings are earthed. Otherwise, there is no complete circuit and very little current would flow.

My bath is cheapo plastic !
 

Offline TheDood

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #30 on: January 30, 2020, 11:34:11 pm »
The water is full of salts or ions, and so is your body (pure water is a poor conductor, needs ions), so conduction should be possible. Voltage would matter if it was great enough that the parallel current flow through your body was sufficient to meet the threshold of bodily damage. 

Resistivity is the amount of resistance with respect to how far you are away from a source. Its units are Ω·m, or ohm-meter, or the amount of ohms per meter of seperation. It's based on the lead/probe surface area, and the distance of the conduction path. How many amps pass for a given voltage when probes are at certain distance apart and have a certain surface area.

ρ = (ΩA)/L

ρ = resistivity
Ω = ohms of resistance
L = proximity of conductors
A = surface area of conductors

When you're in the bathtub with a sunken energized cable, you're effectively creating a cct with yourself as 1 resistor and the bathwater as another resistor, in parallel. Depending on your body EC and the bath water EC (resistivity = 1/EC), a resistance can be calculated for both "resistors," (yourself and the bathwater), and because parallel ccts have the same V across the parallel components, one could see it's not hard to electrocute.

After a quick Google search I found 150mA to be a lethal current flow for humans, so if your cord were 120V..

V = I·Ω

120V ÷ 0.15A = 800Ω

...and the conduction route through your body were 800Ω or less, you're a goner! (Not sure how long 100mA - 200mA needs to flow though)
« Last Edit: January 30, 2020, 11:37:43 pm by TheDood »
 

Online Circlotron

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #31 on: January 31, 2020, 12:03:17 am »
If the problem was shoddy chargers, wouldn't they be destroying phones, regardless of the vicinity to a bathtub?
Mobile phones are completely floating, electrically.  Mains voltages would cause the entire device to attain a potential with respect to the world around it, but internally, there is no such risk.

But add a path to ground and things change.
Just like a bird perched on a high voltage wire.
 

Offline KL27x

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #32 on: January 31, 2020, 03:07:09 am »
^Yeah.

The death camping light is an example where I can maybe imagine the incompetence. One guy designs a camping light with an internal charger. Cheap as possible. Then someone comes along and decides to add a 5V USB port on it, just connecting the internal/enclosed battery charging traces to the USB port. Then you get the oopsie when someone dies.

If you buy the $10 phone charger from the airport that has $2.00 BOM and manufacturing cost, I don't think that will have mains on the DC side. Improper isolation maybe, but not direct mains short of a malfunction.

And if the charger isn't charging or is blowing up your phone, I don't think you will be trying to use it in the bathtub or anywhere else.
 

Offline james_s

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #33 on: January 31, 2020, 03:30:07 am »
The issue is silent failures, where the charger continues to work but is not providing proper isolation. I don't remember now who it was but I know I saw teardowns of several different cheap USB chargers and many of them had either really sketchy isolation in the transformer itself, or traces and components so close together that something could potentially flash over and bypass the isolation. In places with 240V mains this issue will be amplified.

A GFCI *should* protect the person from death but I certainly wouldn't rely on it to do so, and there are still plenty of houses out there without GFCI protection.
 

Offline tooki

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Re: Why some people died in their bath after smartphone dropped into water ?
« Reply #34 on: January 31, 2020, 08:21:58 am »
I think theirs more to these stories than what is really being told. The average USB charger cable is around 3 feet long or about a metre. Electrical code states that any power outlet must be a minimum of 6 feet or 2 meters from the bathtub or shower or toilet . So as the OP stated it's quite likely that an extension cord was used at the time of insistent . GFCI receptacles are supposed to be installed in bathrooms but I have seen these plugs replaced with standard wall receptacles.
So in a scenario of no GFCI with an extension cord charging a smart phone while taking a bath add up to a very bad day for the victim.
Darwin wins again.   
Remember that most developed countries now require whole-house GFCIs, and that even in ones that don’t (or didn’t at the time of construction) a GFCI outlet can protect additional outlets connected downstream from it. So just because you don’t see a GFCI unit right at the bathroom sink doesn’t mean it’s not GFCI-protected.


But moreover, a GFCI isn’t going to protect against all failure modes. One potential failure mode of horrid cheap chargers is that low-current (but enough to kill, i.e. 50mA-ish) mains AC voltage is superimposed atop the 5V DC.


As for cable length, I use 2m and 3m phone cables daily.



The issue is silent failures, where the charger continues to work but is not providing proper isolation. I don't remember now who it was but I know I saw teardowns of several different cheap USB chargers and many of them had either really sketchy isolation in the transformer itself, or traces and components so close together that something could potentially flash over and bypass the isolation. In places with 240V mains this issue will be amplified.

A GFCI *should* protect the person from death but I certainly wouldn't rely on it to do so, and there are still plenty of houses out there without GFCI protection.
The two channels that do lots of teardowns of horrid Chinese chargers are bigclivedotcom and diodegonewild. Outside of video, Ken Shirriff has done extensive, detailed charger teardowns.

All three of them have found chargers with insanely small creepage distances, as well as transformers where primary and secondary windings touch, with nothing but the enamel separating them. Doesn’t take that much vibration to wear through that!
 


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