The charger is not isolated from the mains would be my guess.
Thatās a really sad story.
I know that it only takes a tiny amount of current to kill someone, and my understanding is that phone chargers put out a full amp or more but at 5 Volts, even in water? Is there generally some sort of sensing circuit that sends power down the line once it confirms that there is a phone attached as opposed to a baby putting the exposed prongs into itās mouth?
Iām (obviously) no expert, but shouldnāt the building code make it hard for a phone charging cord to even reach into a bathtub?
Either way, condolences to the family & friends.
No GFI, or malfunctioning GFI. This is a problem that was solved 30+ years ago.
As best I know, IEC has required GFI in bathroom outlets (and kitchen outlets at countertop height) for at least 20 years.
Better than the British alternative, which is no outlets or switches in bathrooms. That one Iāve never understood.
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This is very unfortunate and sad. What likely happened was direct contact with the main line at 120 volts either by something like a wet hand or an extension cord directly in the water. The power coming over USB isnāt dangerous. The power the charger is plugged into is very dangerous.
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Funny! I was going to post this very thing. I lived there for several years and cracked up every time I needed to recharge an electric razor or use a hair dryer! I used to believe you ācanāt fix stupidā, but the Brits certainly gave it their best shot in this case!
It used to be you didnāt need to tell anyone donāt use electric/plugged-in items around a bathtub (e.g. radio, toaster)ā¦I guess itās a problem now-a-days.
This is likely a result of a cheap USB charger. These devices do not use transformers to isolate the line voltage from the low voltage charge circuit. The result is that there is always a direct path to the mains voltage, even on a five volt line with these devices. This is a result of the basic design, which eliminated the transformer for cost and size reasons.
If the phone had been hooked up to a transformer based charger, she could have dropped the connected phone into the bath with her with no real harm (except possibly to the phone). Cheap and small electronic devices come with some other trade offs. There is a reason that medical devices require fully isolated (which a normal transformer doesnāt provide) power supplies. But at least a transformer based charger would have provided a higher degree of protection. Since these devices are not typically made in America (where our litigious society can provide a means of correcting the manufacturers) there really isnāt anything other then yet more government regulations that could prevent their use.
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Also makes me wonder if the hot and neutral lines were swapped on the outlet. 
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What a weird story,
The video said she was found with burns on her hand. I wish they shared evidence of what happened so we could actually figure it out. Because the story doesnāt seem to make that much since to me.
Apple also sells a extension cord for their wall charger, which would allow the wall current further away from the wall.
@wandrson do you have any chargers like you mentioned? Can we show this issue in a video, might be a good opportunity for a DMS PSA. I could see news networks picking it up and we would be sharing info rather than just feels.
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Underwriters Lab report on counterfeit chargers:
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I would be willing to bet this was the case. It is improper household wiring (which is quite common) which makes these little chargers so potentially dangerous.
I have boxes of cheap USB chargers, with a mix of good and bad. But to be clear, they are all fairly dangerous devices for the reason that @Raymond mentioned above. These devices have direct connections to the mains power supply. If everything is done right (Including the UL insulation and other items @bknapp mentions above) they can be fairly safe. And in most cases failure will only fry your device. However, if the household AC wiring is backwards, these devices become much less safe. They can effectively place the āhotā line on the case or the device. If either has conductivity, you get to meet Mr. Shockyā¦
In the old days, transformerless devices were quite common in the household; however, they had metal housings which were supposed to be connected to the earth ground. This would blow the circuit breaker if the house had a wiring problem or other issue developed. This is the primary reason that this was always considered a bad thing to do
http://homesmsp.typepad.com/.a/6a00e550bbaeb38834010535cadd30970b-320wi
The bottom line is that you donāt want to charge a USB device in your bathroom. It stands a good chance as being the same as operating a hair drier while standing in the bath tubā¦
Even with all the faults he points outā¦ it doesnt show anything other than a few poor design choices. Yeah, no insulation or solder on a couple of itemsā¦ but itās fully enclosed where fingers wonāt get to it. The poor contacts are a terrible idea, but it was probably a compromise to make them quicker and cheaper to produce. Same thing with caps in proximity to the overloaded transformer. Theyāll die a quick death from the heat, but itās a design constraint of packing all that crap into a case designed by a commercial artist for aesthetics.
It would be really cool to set up a test fixture to show some of these cheap chargers and the voltage they can carry on that ground wire or USB shield with respect to earth ground and with miswired outlets in use.
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He does some great, in-depth teardowns with voltage graphing. The biggest issue with the cheap chargers is how insanely noisy the current flow is.
Be sure to check out the side-by-side comparison of the genuine charger vs the counterfeit from a current quality perspective.
Though they seem to be rare, any capacitive dropper based charger is high risk. Any switcher not using a class Y capacitor to bootstrap the secondary has risk. But most of the deadly issues are going to be insulation failures in the small transformers used in switchers, or insufficient isolation between HV and LV sides that either gets solder bridged tying them together in manufacturing, or otherwise compromised.
Just ran across this in a IEEE newsletter:
In the comments thereās this: āSmart screens make dumb kids.ā
You can nitpick the hard ware details all you want. Bottom line is WTH is a kid doing w/ a cellphone in the bathtubā¦
Disconnect
Now Reconnect
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Life is getting busier. Having grown up before cellphones in every pocket, I personally have trouble imagining why a pre-teen needs a smartphone, but the hand-me-down Atari 2600 I had at age 9 was seen as an extravagance by my folksā generation.
However, phone in the bathtub is kinda stretching it. Thatās what nonsense like Alexa is for.
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Iāve noticed a major trend in imported chargers and laptop power supplies that are not UL approved. When I was responsible for UL compliance I had to make sure that every unit I produced passed āhigh potā testing. Guaranteed most cheap chargers would fail this test. That is likely the reason for this failure.
Donāt get me wrong; you should never touch a plugged in device while in the tub, shower, or pool, however if all devices sold in the US were required to have UL approval there would be a lot less of these electrocutions and a lot less lithium ion battery fires.
Too bad that media outlets covering these spectacular failures do not educate the public about the importance of purchasing products with UL approval.
You remember a day when news was about information and public service, not ratings and the owners political agenda.
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Oh. You are so right! Modern media just kills me.
You forgot - and paid product placements. Our local Dallas news stations have at least one built in news story commercial every morning, noon, afternoon, and night.