Charging phone in bath
 

Thing is that if desperate I might have been (and may still be?) tempted to use say a long USB cable to do this with the Mains electricity well out of reach.


Sadly as usual the news seem to be getting it wrong. At least one of these must surely be wrong.


[What is IT? - The charger? - The extension cord? - The phone?]

So which article(s) are incorrect?

I find it difficult to believe that, absent the mains in the bath, dropping the charging phone in the water might have fatal results? 5V is after all surely 5V.

On the other hand, "balancing a mains extension socket on ones chest" when in the bath is clearly a bit daft, especially in a 240V country.

Can anyone shed any expert light on this?

Water and electricity do not mix well

The USB chargers mostly use an electrical design that allows a small percentage of the mains voltage through to charge low voltage devices. Very few of the cheaper systems use a transformer, which would, in theory, completely isolate the mains from the charger output. Instead, a capacitive dropper design is the normal choice for manufacturers, it is cheap, works well but has the disadvantage that one side of the circuitry is connected to the mains. The cheap chargers do not have any form of earth connection, so the output voltage is left floating with respect to earth. Under normal conditions this does not represent a problem.

If you run the back of your fingers along the metal side of a tablet computer or phone while it is plugged in and charging, you will probably feel a little tingle or vibration through your fingers. This is leakage current to earth passing through your body. It is at very low levels, microamps at best and normally completely harmless because your body has a resistance of at least a hundred thousand ohms when dry.

Step into a bath and you reduce the skin resistance dramatically, perhaps to a thousand ohms or less. This allows considerably more current to flow. Add some contaminants such as bath salts to the bath water, and the water conductivity is also vastly increased. Distilled water is effectively an insulator, but add some salt and it readily conducts electricity.

So the floating five volt charger appears pretty harmless, but because the voltage is floating with respect to earth, a much higher voltage can exist between the charger contacts and earth, approximately half of the mains voltage is normal, so 120 volts in the UK.

The next problem is that the mains voltage is not actually 240 volts, that is just the mean value of the sine wave voltage. The peak rises to 315 volts or thereabouts.

So there you are sitting in the bath with a five volt charger, but the actual voltage to earth from either contact is nearly 160 volts. The return earth connection is provided by the copper pipework to the bath. It only takes one milliamp of current to flow across the chest and heart to disrupt the normal heartbeat. An overall resistance of 160,000 ohms is required to limit current to this level. As mentioned earlier, the actual resistance of a body immersed in bath water is probably less than a thousand ohms. This would allow a current of 160 milliamps to flow, easily enough to kill.

Almost certainly, the charger being used in this incident was one of the cheaper after market ones sourced from the Far East, although any device connected to the mains in a bathroom represents a considerable risk to the user unless specifically designed and certified for such use.

I commented on this sad incident on another thread as an example of the lack of awareness of danger many people have today. That was avery interesting post Gouli-Iwas not aware of the different charger types seeing the higher priced ones as just typical branded rip offs. Also was not aware that the instantaneous voltage on mains could be so much higher than 240 V which is quite enough o kill anyway.

In spite of the different types of charger etc is till find it ahrd to understand man of 32 did not realise
1 That you never ever ever mix water and electricity
2 That any charging device has at some point wire in and a wire out, the wire out may only be 5v but the wire in is regular mains.

A sad story

If you must buy another after market charger and you don't want to pay the original manufacturer's price, the Ikea Koppla charger with three USB outlets is a very good and safe choice. So good, I bought four!

Suggest that he could be a candidate for the Darwin award "http://www.darwin--awards.com/":E

GOULI, thanks for the exceptionally informative, illuminating, and interesting post. I've taken a full 240V shock accidentally (not in water), and I can tell you, it very quickly gets your full attention! :eek:

I was repairing a power tool, got a little "switched off" during repeated "power on" testing, and managed to insert a finger into a live active terminal, incorrectly thinking I'd turned the power off! No harm done, just gave me a good little recharge. :)

One thing about those small chargers that I don't like is their propensity to "light up" because of their relatively poor construction and poor quality insulation. Remember, you're reliant on possibly one or perhaps two, overworked, underpaid and lowly-skilled Chinese factory workers to ensure your house doesn't burn to the ground!

As a result, I never leave these things running unattended in an empty house. I've had a simple 3-pin male-female 240V extension lead connector, "arc up" via a straight-out short circuit, and it was pretty impressive to see!

The offending 240V connector assembly was in a workshop, running power to a pedestal drill. The power lead hung down from the wall and could swing in the wind that regularly blew through the often-open shop doors. Years of swinging in the wind created the conditions for the 240V connector short circuit.

I've also been informed that the cheap 240V electric kettles have been known to short circuit and cause fires, when the power switch at the wall is left on, but the kettle is off.

Unless bathroom electrics are executed by someone with saddle sores, one will never see a switch lower than ceiling level and with a hanging cord.
Another tip, never take an electric fire into a bathroom.

I have reproached myself for being sarcastic.

In Spain it's common to see mains plug sockets just above the wash basins :=

With regards to electrical equipment in the bathroom, a friend installed a very fancy cabinet in his shower room. The cabinet formed from stainless steel was fitted with a Bluetooth audio system and heating pads to ensure the mirror on the front remained fog free. The system appeared to be working fine, until he touched the cabinet while shaving and received a shock. I was asked to investigate.

Everything in the cabinet was double insulated and insulation tests showed no leakage between the power leads and the cabinet. Tests also revealed that the cabinet itself was not earthed because power had been tapped off an old lighting circuit, which was so old it was not provided with an earth connection.

What was happening was that steel case of the cabinet was coupling as a huge extra turn to the low voltage transformer supplying power for the audio system. The cabinet was gradually charging up to 300 volts or so while it was in use with respect to earth. Touch the cabinet and you got a brief but severe shock, especially standing on a damp floor with wet feet! There was no electrical connection between the cabinet body itself and the mains, but still an electrical shock risk existed.

Once the cabinet was connected up properly to the mains supply with the cabinet bonded to earth and all the other bathroom appliances, everything was fine. This involved some heavy duty drilling through a double wall to route a proper power cable, which is why my friend had taken the easy option of tapping into the lighting circuit. Everything was working just fine until he used the shower and the cabinet had been powered up for some time.

Even simple electrical work carries risks if you don't fully understand what is going on.

For heaven's sake - can't one even take a bath nowadays without feeling withdrawal symptoms from a phone!!

On a humbler scale, when changing a lamp bulb, do not assume that the fact of having switched off at the wall, or at the lamp, means that both pins in the socket are safe - it ain't necessarily so !

A mains-testing screwdriver should be in every toolkit.

As for the chap who took his charger into the bath, suggest a candidate for "The Most Highly Derogatory Order of the Irremovable Digit" (remember, anyone ?)

Back around 1993-4 I was living in Naples. Hot water to the bath was provided by a "scaldabagno" electric immersion heater above the bath. Water in Naples is very hard and soon after we moved into the house the immersion heater stopped working. The workman who arrived to repair the fault tried to drain it, but the calcium had blocked the drain tap. He then removed the heater element (with some difficulty) which was on the base of the cylinder and then started to drill out the built up calcium using a mains powered drill. He ignored my protestations and survived - at least for that day.

We came perilously close to losing our daughter when the wire going through a smoothing iron's springy wire tensioner rubbed through and touched the metal spring coil. The iron was in those days, earthed.

Worst scenario: one hand on the earthed iron, and one on the springy thing. Her worst problem was the muscle strain from being thrown backwards.

I was one of the first folk I know of to protect my home with an RCCB (RCD OR RCB) It worked well.

I have a box of in-line computer lead breakers with 10mm sensitivity. Job lot from Bull Electrical on the south coast. "We're surprised they haven't sold better." the guy said to me. But folk back then just didn't realise that they were the most intelligent, brilliant invention since the wheel.

depending on where youare in the world you can or used to be able to find some alarming socket /plug combinations. US Caribbean seemed one of the worst with flimsy two pin plugs and for higher powered devices a horrid earthed version that seemed to be made entirely of metal with some bits cardboard as spacers/insulators. I image they do not make them any more but on older devices who knows. we had a horrendous installation in my house with an undersink water heater and dishwasher on same circuit-turn on washer hot water but not hot enough runs into dishwasher. -cools down water in heater. On comes heater in dishwasher AND undersink heater at s ame time and zap off goes the power. So if you dont remember to turn one off then the other and the first back on it wont work and then off to the astonishing fuse board with all sorts of naked connections and weird fuses made of glass or lumps of ceramic with exposed metal ends that pushed into big copper sprung forks

The standard Euro plug is probably the best followed by our own and then maybe S Africa who have a sort of hybrid European/Aussie device. I think in Northern Europe we have much the safest designs and installations of anywhere -so long as people understand enough to know that you do not touch anything without turning off at the consumer unit or in this case mix electricity and water ever. What did people under 35 learn at school??

While neon screwdrivers can give an indication of a live connection, lighting conditions and various combinations of wiring can result in the neon glow being invisible or absent. Floating high voltages will not necessarily light a neon bulb. A far safer alternative is a non contact voltage tester. These are available for a few pounds from most DIY and trade outlets. They run off a couple of AA or AAA batteries, so always check that the voltage tester works on a live part of the circuit before checking a suspect bit is truly powered down! Fitting a couple of Lithium batteries should ensure these devices work okay for up to ten years. Alkaline and zinc carbon batteries need frequent checking to make sure they are not leaking or have run flat.

In the absence of nothing better, a neon screwdriver can give an indication that a circuit is live, but are you comfortable betting your life on it? A suitably rated multimeter is my personal choice when checking for voltages.

Had an interesting mains incoming fault the other week.
Of the infeeding 11KV 3 phases to the local substation two had shorted and gone bang.
That left one phase live - mine.
The result was "interesting"
The RMS value of the incoming supply to the house shot up from 240 volts to 281Volts before 'settling down' to 275Volts.
...and there it sat - while I got on the phone and after about an hour they wound down the tap changing transformer somewhere further back to reduce it to around 250volts while they pondered what to do next. (install a generator on a lorry outside the local substation was the answer while the cable was mended over the next few days)
I noticed it as I was in a room with an incandescent lamp which suddenly got much brighter and my computer's UPS intervened to safeguard things as the volts were way too high.
I was rushing round the house switching things off!

!In our previous house, the light switches were incorrectly fitted in the neutral lines, not the live, thus leaving every fitting live when off!

andytug

Switching the neutral wire was thought safer a long while back when switches were made of brass and ebonite and there was no earth connection in the lighting circuits. The high voltage was kept out of harms way near the ceiling. Older properties can conceal a multitude of traps for the unwary electrician or DIYer.

Even further back, electrical wiring consisted of two bare copper conductors stapled to the wall and covered with a wooden lath. I am led to believe my grandfather wired up several hundred new build houses in the Leyton area of London using this method as late as the 1920s.

I don't touch anything electrical without giving everything a going over with a multimeter. Saved me grief twice. Once when someone (a company electrician) had wired the neutral (not the active) to the main isolation switch to a machine I was working on..
After that incident they installed padlocks on the isolation switch so I had to wait hours for someone to turn up to isolate. I'd do my stuff on the machine then wait hours again for the de isolation in order to check my work. PIA! Especially when I needed multiple isolations to find and fix the fault. Lucky I was paid by the hour but talk about frustrating....

GOULI- had a similar experience in my mum's house, built in the 1950s/60s and wired with rubber insulated wiring, 50 years later had an issue with a socket in the outhouse, took the front off to find the insulation had crumbled into dust leaving two bare wires. House since rewired throughout!

I had my house (in a small country town) burn down due to an electrical fault in the power supply line in the street.
My house and adjoining workshop were supplied with 3 phase power, 4 wires on poles ran up the street; 3 single phase wires and a neutral wire.

I went to work, 80 kms away, for the day - and it was a stormy day with gusty winds in early October, but no rain.
The electrical supply wires between the poles had apparently sagged a little between the poles, with age.
In the gusty winds (70 to 80kmh), one of the phase wires between the poles flicked up and laid over the adjoining neutral wire. This then fed current into the neutral wire - around 90V - thereby boosting the current going into the house to 330V.

I had a bedside electric clock which arced up with the overvoltage, melted the plastic clock housing; and this then set fire to the adjoining window curtains.
I came home in the early evening to find my house a charred ruin, and the local fire brigade in attendance.
The firies (local volunteers) told me they'd turned the power off and pulled the fuses out of the main switchboard - but when they'd started pulling sheets of iron off the roof, they'd raised electrical sparks!

Early next morning, the local power authority inspector arrived, and checked the main switchboard. He found the neutral wire into the house still carrying 90V!
Of course, there's no fuses for neutral wires, only for the active wires.

Nothing was ever said about the power supply fiasco, and my insurance company paid out on the house damage.
Nothing could compensate for the loss of priceless photos and dozens and dozens of other personal possessions that were lost in the fire, though.

Later on in the month, the power utility ran all new wiring up the street; indicating to me that they realised they had a major problem. However in those days (1982), it wasn't legally possible to sue a power supplier for a power supply fault or resultant damage.
The Ash Wednesday bushfires (wildfires) in South Australia, only a little over 4 mths later, reset the blame game.
It was proven that numerous Ash Wednesday bushfires were started by clashing powerlines, and also started by a number of fallen power wires, which landed on vegetation that that was too close to the wires.

The victims of the Ash Wednesday bushfires commenced a class action against the power supplier, claiming negligence on their behalf - and the victims won, snaring a compensation payout of somewhere around $480M in total.

If only I could have been able to do the same, I would have been able to secure a substantial compensatory payout for my personal losses in my house fire, that was no fault whatsoever of my own.

A fascinating thread. Having lived in several countries, I've seen my share of electrical near-disasters.

The "best" one was my house in Jakarta, where the supply to the house was three-phase 240 v. Because it was a new house, I decided to check the electrical outlets. Some of them had been wired across two of the phases, instead of one phase and neutral!

The installers had also circumvented a problem with the distribution-panel box being too shallow, by cutting holes in the panel door, to allow it to close. All very well, except that live terminals of the main fuses were now sticking out of the holes!

Avitor,

You were being UK-centric in your comment about bathroom switches! You should have said:

"In the UK, one will never see a switch lower than ceiling level and with a hanging cord. Everywhere else, one will see normal switches in normal locations." ;)

When my late father first moved to Menorca in the early 1970s, electricity was still somewhat...quaint and unusual.

In his first flat, half of the flat was wired for 127V and the rest was on 230V. Which could be interesting as the sockets weren't labelled!

A friend had rather a posh hi-fi system and was concerned about Menorcan voltage stability upsetting it. So he bought himself a very expensive auto-transformer. The output voltage was monitored and a motor would move the secondary winding tap as required to maintain the correct voltage if the input value fluctuated. None of today's solid state business, it hummed away in a stout, well-insulated metal cabinet.

But after a few weeks, he found that the input voltage had stayed rock-steady at 230V throughout!

I still have my Flying Kit Odds and Sods Box, loaded into my suitcase before every flight, which contains to this day a pair of wires, bare at one end and soldered to a small crocodile clip at the other, these, with a box of old fashioned wooden matches ( remember them ) solved any foreign fitting for which I didn't have the correct adaptor. ( poke wires in socket, stuff used wooden match - or unused if one really wanted to play with fire ! ) into the same hole to secure, and carefully clip to the prongs of the plug of ones' electric razor, or "Dipstick" coffee making mini immersion coil. Providing that the arrangement didn't touch anything, i.e. remained more or less in mid-air, and one had sufficient length of cable to conduct ones' task so that the arrangement didn't move, and wasn't balanced on the edge of the washbasin - no problem. Remove before leaving the room to the mercy of the maid.

Coffee making "dipsticks". These were initially only available for purchase in the USA, and so were made for 110 volts, which meant that one had to be a bit cautious, and ready to unplug quickly if attempting to use them with a 240 volt supply. However, the F/Eng and I were perusing a bazaar in New Delhi one day, Lo ! and Behold ! we espied 240 volt "dipsticks", securing one each we hurried back to my room and proceeded to use mine by boiling water in the bathroom. Some time later, having started to swap War Stories and totally forgetting the passage of time, we saw black smoke pouring out of the bathroom door ! The glass of water had boiled dry and the gadget caught fire, setting the towel on which I had placed the glass on fire as well.

We put out the towel fire, and noticed that the some of the bathroom was covered in a sort of greasy black residue, so opening the room door and seeing a maid down the hall I beckoned her to join us and crossing her palm with an ample supply of Rupees suggested that she might clean the bathroom ? She readily agreed and also said that she would "smuggle" the burned towel out of the hotel when she went home. That earned her some more Rupee entitlement.

Do I earn a Darwin Award ?

You were on track! :}

Can't Trust Those Pesky Inspectors & Electicians
 

A couple years back, I was helping a friend settle into her brand new home. One of my tasks was replacing all of the toggle type wall switches with those "Decora" style paddle things.

Although the home had been inspected and signed off, we called the city and the electrical contractor back for some rework after I discovered loose wires on every switch I removed.

Most disturbing was that many switches in modern homes go to one section of each outlet in a room, so that you plug in floor lamps and operate them easily.

Downside is that people tend to plug other things -- like vacuum cleaners in.

In the UK, I think you're supposed to fit round pin socket outlets to use with floor and wall lights etc if you want to operate them in conjunction with a conventional wall switch (5 amp max?). These are not compatible with higher power socket outlets which in the UK are square pin so of course you can't plug them into a low power outlet under any circumstances.

... and of course after 'Two Jags' gift of Part P of the building regulations, only a qualified electrician may wire up anything unless you want to shell out 250 notes for the building inspector to come and certify your handiwork.

In the US, most circuits are 15 amp. There are some 25 amp circuits, but most of the kit you can buy which takes that kind of power will also plug into a 15 amp outlet.

It's a dog's breakfast, in other words.

Normally, everything's pretty abuse tolerant, meaning you can usually draw enough to trip a 15 amp breaker without heating the wiring up too much.

Unless, of course, you've failed to tighten the screws on the outlets and switches.

Then you build up a lot of heat.

One thing that bothers me is that it's perfectly okay to use plastic junction boxes. They supposedly won't support flame once the source of heat is removed, but I've tossed a few of those blue bastards into a fire on occasion, and they'll burn like candles as long as they're hot enough.

Like when there's a pair of arcing wires inside, creating little pulses of sun-hot copper and brass plasma.

Go figure.


I've been thinking about this, too. Some of these little power supplies -- chargers, adapters, so forth -- have a lot of leakage from the mains to, say, the shell of a USB port. This is mostly true of inexpensive replacement units.

You could fry yourself just by using one and standing on a wet surface, or touching something with a good ground. Like a faucet, or the water in your bathtub.

Be careful!

I read an article once where the thrust of the story was, a lot of American homes were wired up with electrical wiring that was aluminium.

The metal is prone to corrosion at the best of times, but with the 110V standard, American wiring carries a higher amperage for a given wattage, thus increasing the heat load on the wiring.

The article spoke of numerous house fires in America that were caused by corroded aluminium wiring at connections, aided by the larger variation in the heating and cooling cycles of the wiring, as compared to the higher voltage countries.

CarsonDunlop.com - Home inspector training - the true story behind aluminum wiring in the U.S.

This was a HUGE problem in the manufactured housing industry back in the 1960s and 1970s.

There are specific outlets and switches which must be used with Al wiring. Corrosion is one problem, coefficient of expansion is another.

Al expands and contracts more than brass or copper. It will actually stretch the terminal screws over time, loosening the connection and creating resistance.

I don't think you can do a new build with Al wire anymore, and I think if an electrician runs into it during repair work, the home owner is probably in for a spendy surprise.

But, yeah, there have been lots of fires. A friend of mine lost her daughter two years ago to a house fire caused by someone using Al wire in the attic to repair a run of old wire that had been eaten by squirrels. A hundred year old farm house, dry as tinder upstairs.

Bad stuff, that electricity, if you don't respect it.