Why some people died in their bath after smartphone dropped into water ? - Page 1
Forum section: electronics / beginners

author: tigrou
author_rank: Regular Contributor
timestamp: January 27, 2020, 09:29:36 am
content: There is several cases (reported by media) of people dying after their smartphone (while being charged) dropped into the bath and electrocuted them.AFAIK most USB chargers deliver max. 5V, which is non lethal.Because of ohm's law, you need a much higher DC voltage than that to get enough current flowing trough your body and killing you.So I don't understand how it is possible.The possible explanations I see are :- they get killed not because their phone dropped into the water, but because the charger itself dropped into water (eg: not plugged into socket directly but plugged into an extension coord).- the human body resistance is considerably lower while in the water, making 5V (and enough amps) dangerous.- under some conditions, some chargers (eg : counterfeit ones with improper isolation) will deliver more than 5V.- lithium battery capable of delivering high voltage when dropped into water while being charged.

author: BravoV
author_rank: Super Contributor
timestamp: January 27, 2020, 09:35:23 am
content: Quote from: tigrou on January 27, 2020, 09:29:36 amYou missed this one too ...The phone plunged into the bath-tube, either connected or NOT connected to the charger (doesn't matter), and the owner panicked and did some jerk movements, as bath room is wet & slippery, and then fell down and got knocked in the head unconsciously, and drowned in the bath tube.

author: thinkfat
author_rank: Unknown
timestamp: January 27, 2020, 09:38:30 am
content: I suggest watching bigclive on YT tearing down cheap USB wall warts for an explanation.

author: iMo
author_rank: Super Contributor
timestamp: January 27, 2020, 10:10:01 am
content: The most people die from heart attack when they realize their lovely smartphone dropped in the water

author: Gyro
author_rank: Super Contributor
timestamp: January 27, 2020, 10:10:27 am
content: All the theories and explanations you could want...https://www.eevblog.com/forum/chat/hugo-14-electrocuted-in-his-bath-because-of-his-mobile-phone-!/https://www.eevblog.com/forum/chat/man-dies-charging-phone-in-the-bath/https://www.eevblog.com/forum/chat/another-tragedy-cellphone-chargers-and-bathtubs-don_t-mix/https://www.eevblog.com/forum/chat/teen-dead-after-rolling-on-to-iphone-cable-in-her-sleep/https://www.eevblog.com/forum/chat/is-this-really-likely/

author: atmfjstc
author_rank: Regular Contributor
timestamp: January 27, 2020, 12:24:39 pm
content: Quote from: tigrou on January 27, 2020, 09:29:36 amDon't take this as 100% medical advice, but AFAIK, although the resistance of human skin is considerably lower when wet, it is still not low enough for 5 volts to be lethal. You'd need to apply the voltage directly to your internal organs to get a serious effect.Quote from: tigrou on January 27, 2020, 09:29:36 amA cell's voltage is fundamentally limited by the electochemical potential of its electrodes and can never go much above 4-5V no matter how you abuse the battery. To get a higher voltage you need an external circuit with some inductance. Or put more cells in series, but I don't think they use more than 7.4V in mobile phones.Looking at the two articles mentioned it seems the real causes of such electrocutions are:- The charger itself being dropped in water (which means the full line voltage going into the charger is now applied to water)- 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....

author: Prehistoricman
author_rank: Regular Contributor
timestamp: January 27, 2020, 01:31:56 pm
content: Quote from: atmfjstc on January 27, 2020, 12:24:39 pmImportant 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.

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: January 27, 2020, 02:52:01 pm
content: Quote from: thinkfat on January 27, 2020, 09:38:30 amI think that is likely to be #1 reason.We don't know if the phone was dropped in the bath as a cause or result of death. It's possible a shock was received by holding the phone with damp/wet hands.Also, is it possible to get a shock across the chest without a path to Earth required? For example, hold a live and neutral wire in each hand, and the loop through the arms and chest will provide a circuit. A voltage across the chest (and therefore the heart) is the most dangerous path.

author: mikerj
author_rank: Super Contributor
timestamp: January 27, 2020, 03:21:44 pm
content: Quote from: Prehistoricman on January 27, 2020, 01:31:56 pmThey will be bonded to earth in many/most houses if copper pipes are used, and there will likely be leakage down a wet waste pipe. Even if the metal parts were isolated a bathtub full of water likely presents a high enough capacitance to ground to cause an uncomfortable amount of current to flow.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 27, 2020, 07:49:03 pm
content: Quote from: tigrou on January 27, 2020, 09:29:36 amYou missed: it is just an urban legend and didn't actually happen. Just like the guy supposedly killed by the 9V battery in an ohm-meter by piercing his skin with the probes.But defective mains isolation and knocking an extension cord into the bath are both possible as well.

author: james_s
author_rank: Super Contributor
timestamp: January 27, 2020, 07:54:23 pm
content: Considering what I have seen inside cheap knockoff phone chargers, it would not surprise me in the least if someone is shocked, potentially lethally by an isolation fault, especially in 240V land.

author: Refrigerator
author_rank: Super Contributor
timestamp: January 27, 2020, 08:12:04 pm
content: There are chargers that have their primary and secondary winding wires lay on each other without any additional insulation and this could very easily cause an electrical connection between the two if the enamel insulation on the wire got damaged.DiodeGoneWild made some videos on dodgy chinese chargers:

author: AVGresponding
author_rank: Super Contributor
timestamp: January 27, 2020, 08:19:43 pm
content: Quote from: thinkfat on January 27, 2020, 09:38:30 amSome of the gear he pulls apart is hilariously scary; it's not unusual for him to discover line voltage directly on the USB socket

author: tooki
author_rank: Super Contributor
timestamp: January 29, 2020, 09:24:32 pm
content: Remember when BigClive joked one time about the next thing being the Chinese making a USB charger from a capacitive dropper, and then within a year, he tore down the “gay death dalek” camping light which, lo and behold, had a capacitive dropper USB charger? 240V mains on a USB port...

author: Brumby
author_rank: Unknown
timestamp: January 29, 2020, 11:45:06 pm
content: Quote from: tigrou on January 27, 2020, 09:29:36 amForget about the 5V. The actual stated voltage delivered by the charger has NOTHING to do with the problem.QuoteThis is the area your thinking needs to explore. Aside from the obvious situation of a charger being dunked in the bath water where mains can come into direct contact with the water, in poorly designed/constructed chargers, other paths can exist for mains power to go where it shouldn'tSee other posts above for links to examples.

author: KL27x
author_rank: Super Contributor
timestamp: January 30, 2020, 12:30:29 am
content: Even considering the possibility of shoddy chargers, that had nothing to do with the majority of the deaths.E.g., one girl thought to have touched a frayed mains extension cord while in the bath. One young man thought to have set his CHARGER (not the phone) on his chest while laying in the bath; i.e. he set the extension cord and charger plug directly on himself. Both peeps plugged the extension cord into a non-GFI outlet.If the problem was shoddy chargers, wouldn't they be destroying phones, regardless of the vicinity to a bathtub?

author: JustMeHere
author_rank: Frequent Contributor
timestamp: January 30, 2020, 01:09:13 am
content: The case I know about, the girl had her charger plugged into a damaged extension cord.

author: Brumby
author_rank: Unknown
timestamp: January 30, 2020, 01:13:54 am
content: Quote from: KL27x on January 30, 2020, 12:30:29 amMobile 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.

author: Brumby
author_rank: Unknown
timestamp: January 30, 2020, 01:18:39 am
content: Quote from: KL27x on January 30, 2020, 12:30:29 amQuote from: JustMeHere on January 30, 2020, 01:09:13 amThank the Media for sensationalising such stories. They take the attention grabbing subjects of "phones" and "injury/death" in order to get an audience - especially for headlines - and don't get too excited about being more detailed until later in the article, if at all.

author: amyk
author_rank: Super Contributor
timestamp: January 30, 2020, 01:20:08 am
content: Even if there was an isolation fault, a phone dropped into the tub would make the current seek the ground, it won't take a detour through your body --- unless you grab it and it's metal, which is what I suspect happened in a lot of cases.

author: james_s
author_rank: Super Contributor
timestamp: January 30, 2020, 01:27:51 am
content: It's going to be people holding onto their phone while sitting in the bath with the phone plugged into the charger. I wouldn't do that myself but it's very common behavior, people have run down the battery and want to sit there watching videos or playing games on their phone so they plug it in. Lots of phones have metal components that you can touch easily, and if a charger fault causes those to be live then you're in for a bad experience.

author: Jwillis
author_rank: Super Contributor
timestamp: January 30, 2020, 01:38:27 am
content: Quote from: amyk on January 30, 2020, 01:20:08 amThat's not entirely true . The current does not take a direct path in water to a common ground or on contact with the earth, but creates a varying potential radiating outward from the point of contact. So being a body of water can still be lethal as one point of the human body can be put at a different potential than another part of the human body. It only takes a few milliamps to cause heart failure. And in a wet environment the resistance from one potential and another can be quite low only requiring very small voltages for the current to cross potentials.

author: KL27x
author_rank: Super Contributor
timestamp: January 30, 2020, 04:11:48 am
content: QuoteBut has this ever happened? I personally do not know of any such cases.QuoteIf this CAN actually happen, someone could demonstrate it and put it on Youtube. Just take one of these chargers that is somehow putting full mains (and mains - 5V) directly to the phone (full mains, not high impedance capacitive coupling of microamps) and showing how you plug the usb cable into the end of a hot dog and then grounding the other end and instantly cooking the weiner.I don't see how this can happen and get sold like that. Nothing coming out of the charger should be directly connected to mains. If you cut the cable and touched it without wearing shoes, you would get shocked. If you were standing on wet ground, you could be electrocuted. This does not compute with realworld experience with cheap PSU's. I mean, if you touch the DC output (either the + or the -; dunno which; try both?) to ground, this would blow your breaker? You're saying that one of the DC output wires is direct mains!? I don't believe this is for sale and making it to the US even through Alibaba.They can be dangerous if they fail. Dropping the DC output end into water/ground should not cause any problem other than short/current-limiting, unless the thing has also happened to fail in some other way at the same time?

author: Jwillis
author_rank: Super Contributor
timestamp: January 30, 2020, 04:48:54 am
content: 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.

author: AVGresponding
author_rank: Super Contributor
timestamp: January 30, 2020, 05:54:12 am
content: Quote from: KL27x on January 30, 2020, 04:11:48 amEbay and Alibaba arefullof this cheapo dangerous tat. There arecountlessyoutube videos, search bigclivedotcom to start.

author: KL27x
author_rank: Super Contributor
timestamp: January 30, 2020, 08:08:31 am
content: QuoteSo 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.

author: Jwillis
author_rank: Super Contributor
timestamp: January 30, 2020, 11:07:19 am
content: 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.

author: Brumby
author_rank: Unknown
timestamp: January 30, 2020, 12:41:44 pm
content: Quote from: KL27x on January 30, 2020, 08:08:31 amFTFY

author: james_s
author_rank: Super Contributor
timestamp: January 30, 2020, 06:36:23 pm
content: Quote from: Jwillis on January 30, 2020, 04:48:54 amLonger 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.

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: January 30, 2020, 07:52:29 pm
content: Quote from: Prehistoricman on January 27, 2020, 01:31:56 pmMy bath is cheapo plastic !

author: TheDood
author_rank: Regular Contributor
timestamp: January 30, 2020, 11:34:11 pm
content: 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)/Lρ = resistivityΩ = ohms of resistanceL = proximity of conductorsA = surface area of conductorsWhen 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·Ω120V ÷ 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)

author: Circlotron
author_rank: Super Contributor
timestamp: January 31, 2020, 12:03:17 am
content: Quote from: Brumby on January 30, 2020, 01:13:54 amJust like a bird perched on a high voltage wire.

author: KL27x
author_rank: Super Contributor
timestamp: January 31, 2020, 03:07:09 am
content: ^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.

author: james_s
author_rank: Super Contributor
timestamp: January 31, 2020, 03:30:07 am
content: 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.

author: tooki
author_rank: Super Contributor
timestamp: January 31, 2020, 08:21:58 am
content: Quote from: Jwillis on January 30, 2020, 04:48:54 amRemember 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’tseea GFCI unit right at the bathroom sink doesn’t mean it’snotGFCI-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.Quote from: james_s on January 31, 2020, 03:30:07 amThe 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!