Suicide shower head teardown

[1xrtt]

Regarding the statistics: what's to say they're reliable? I doubt they're well recorded at all.

It's likely that shocks from these showers might not directly kill the person but they could cause them to slip and fall, resulting in severe injury/death.

Risks are a part of everyday life but it's crazy when they're unnecessary and can be mitigated so easily.

Considering these statistics are the only one I could find, I agree that we should read them with a bit of skepticism. If anyone can find more reliable sources, I'm all for it.
However, take them out and what we have left? Our own assumptions and anedoctal evidence. I'm even more skeptic on those.

I don't believe the design of device in itself is unsafe. Changing the shower head for a different design? There are other options, like solar heating and gas heating, but those are expensive and not practical on the vast majority of the country.
The only practical mitigation would be to do a correct installation, with proper wiring, connections and earthing. Also, consider that what most of people in this forum call "earth connection" is not a common practice in many households here. I'm not a certified electrician, but what I see most do is to attach neutral and ground together and call it a day. This is described in the Brazilian Norm NBR5410:

http://www.iar.unicamp.br/lab/luz/ld/normas%20e%20relat%F3rios/NRs/nbr_5410.pdf

Google translation of  page 15, Chapter 4.2.2.2.1:

scheme TN
The TN system has one point directly grounded the power, and the masses connected to this
point through conductive protection. Are considered variants three TN system, according to
provision of neutral conductor and protective conductor, namely:
a) S-TN scheme in which the neutral conductor and the protective conductor are distinguished (figure 1);
b) TN-C-S system, in part of which the neutral and protection functions are combined into a single
conductor (figure 2);
c) TN-C scheme, in which the neutral and protection functions are combined in a single conductor, in
entire scheme (Figure 3).

[KL27x]

You know how when you stand on set concrete in bare feet, it's a bad idea to grab a live mains wire? That's because the concrete and water earth one end of you. And electricy has nowhere else to go but through you, even though you are a terrible conductor. Well this is completely different.

In the shower, presumably your feet are not well grounded, because you are standing on ceramic or plastic tile/tub, or whatnot. And once you're wet, there is an alternate path over the surface of your skin that should be much more conductive than your body. So any shock could be more of a wakeup call than an electrocution. As is apparently the case:

With all-metal showers, we really took a violent electric shock if touched the shower or the switch in operation.

So as uncomfortable as it might make you, at first glance, there's a reason that these are so popular. And I don't think it's because if you're poor enough you would rather die than take a cold shower.

I think the worst thing you could do it to reach up and touch the device with one hand while touching a grounded knob/pipe with the other. In this case, hopefully you are really wet and lathered up, and have good reflexes. I wonder if they teach kids on how to shower in Brazilian schools?

FWIW, anyone that uses a laminator to make pcb's is taking a walk on the wild side. The metal rollers are in contact with fairly low impedance mains. And when you put the board in, it's live. Wear your shoes when doing this.

[Zero999]

Regarding the statistics: what's to say they're reliable? I doubt they're well recorded at all.

It's likely that shocks from these showers might not directly kill the person but they could cause them to slip and fall, resulting in severe injury/death....

With the older metal shower, you may receive an electric shock if the metal case was not grounded.
That's happens several times with me but I never fall or slip for this reason.
As I said, the contraction of the arm muscles don't let you in contact with the shower and current is interrupted.
With the all plastic shower, no conducting parts can be reach and there is no risk of electric shock...

Perhaps if you take a shower with salt water....

Measuring resistance between a metal case shower and water falling (tap water) :
- at 10 cm from the shower, resistance infinite. (no current at all in the body)
- at 5 cm from the shower, more or less 300K. (more or less 0.5mA current for 130Vac phase/ground)

May I ask how old are you & where do you live? You seem like quite an experienced older chap.

Were those resistance measurements taken with a normal multimeter or using a high voltage? If you watch the video, he found the resistance of water decreased a lot at mains voltages, compared to the value indicated on his multimeter.

[MagicSmoker]

...
I don't believe the design of device in itself is unsafe. Changing the shower head for a different design?
...

Oh, there is no question that the design of this thing is unsafe.

But simply replacing the bare resistance wire that is directly immersed in the water stream with a conventional insulated water heating element would go a long way to making this safer (both greatly reducing the potential shock hazard as well as electrolytic corrosion of the heating element).

And yes, I saw the post earlier whining about how this was tried but it didn't heat the water as efficiently... What a load of crap - just design the thing so that the water spends more time in contact with the heating element. I mean, really... This is not rocket science, people.

[Zero999]

Yes, the bear element is unsafe. If it breaks then a good earth connection is all that's protecting you from a nasty shock.

There's also no thermal fuse, so if that crappy pressure sensitive switch fails in the on position, it will catch fire when the water stops flowing.

In addition to a closed element, a thermal fuse and bi-metal strip are needed for fire protection.

Electric showers exist here in the UK but the heating element is inside a water tight enclosure, the exposed metal surfaces are properly earthed and  a thermal fuse protects against fire.

[Don Hills]

I've been around a very long time & I've never seen the "couple of close spaced plates" type ...

I used to travel to Aus a lot in the 80s, stayed in hotels and serviced apartments. I saw the plate type a couple of times. Two square plates, dome shaped with central holes, separated by ceramic spacers. 

(1) As long as the lid was down,you had no access to the water or the element-----none of the ones I saw (hundreds) would allow insertion of the power plug into the kettle body without the lid being closed.
(Of course,if the lid is broken,or removed,all bets are off,as you could then touch the connections to the element.)

Apparently removing the lid was not unknown, especially for the practice of "hotting the pot" (preheating the teapot) by placing it on the open kettle. OK for a china teapot, but I remember an anecdote in an Electronics Australia magazine, where the author was visiting an office where he heard a juicy "splat" followed by a feminine squeal. Apparently the typists were brewing the morning cuppa, and placed the aluminium teapot on top of the lidless kettle at just the wrong angle...

[vk6zgo]

I've been around a very long time & I've never seen the "couple of close spaced plates" type ...

I used to travel to Aus a lot in the 80s, stayed in hotels and serviced apartments. I saw the plate type a couple of times. Two square plates, dome shaped with central holes, separated by ceramic spacers.   

It may have been an '80s thing----that was the decade when the "everything Australian is bad---everything from Overseas is good" meme first took hold,with consequent loosening of standards.

They could have been a special job lot for the hotel chains,but were never contemporary with the kettles shown in your link,which were more of a '50s/'60s thing.
By the 1980s,insulated element kettles were starting to make inroads into the market.
I certainly never saw the dual plate units either for sale or in service.

(1) As long as the lid was down,you had no access to the water or the element-----none of the ones I saw (hundreds) would allow insertion of the power plug into the kettle body without the lid being closed.
(Of course,if the lid is broken,or removed,all bets are off,as you could then touch the connections to the element.)

Apparently removing the lid was not unknown, especially for the practice of "hotting the pot" (preheating the teapot) by placing it on the open kettle. OK for a china teapot, but I remember an anecdote in an Electronics Australia magazine, where the author was visiting an office where he heard a juicy "splat" followed by a feminine squeal. Apparently the typists were brewing the morning cuppa, and placed the aluminium teapot on top of the lidless kettle at just the wrong angle...

I remember that article----I always thought it would be hard to balance a teapot on the ones I knew,because of their shape (we used to call them "electric jugs")
"Hotting the pot" was always a silly idea,& went the way of the Dodo with the introduction of teabags,& the change by many to Coffee drinking.

Oddly,the only places I ever saw kettles without lids were in some small businesses I visited.

I never saw a lidless one in anyone's home.

[oldway]

In case of electric shock, current must be higher than 30mA to be dangerous or even lethal.

With those old metalic showers, this current was not reached because they were only 130V (130V - neutral) and there still exist a current limiting resistor made by water between phase and metalic case.

 @Hero999:

Were those resistance measurements taken with a normal multimeter or using a high voltage? If you watch the video, he found the resistance of water decreased a lot at mains voltages, compared to the value indicated on his multimeter.

Resistivity of water changing with voltage ? Never heard that water should have such behaviour !

The infinite resistance at 10cm from the shower shows that it became droplets and that there is no electric shock possible by falling water at this distance.

It has been measured between the metalic case of the shower and a metalic plate placed under the shower.

In addition to a closed element, a thermal fuse and bi-metal strip are needed for fire protection.

The automatic pressure switch is very simple and very secure as the most commun failure is rupture of the rubber pressure disk. In this case, the switch remains open. No risk of fire at all.
Even if the shower would catch fire, this is not that dangerous because there is nothing updown the shower in a badroom that could also catch fire.

[HackedFridgeMagnet]

In case of electric shock, current must be higher than 30mA to be dangerous or even lethal.

With those old metalic showers, this current was not reached because they were only 130V (130V - neutral) and there still exist a current limiting resistor made by water between phase and metalic case.

 @Hero999:

Were those resistance measurements taken with a normal multimeter or using a high voltage? If you watch the video, he found the resistance of water decreased a lot at mains voltages, compared to the value indicated on his multimeter.

Resistivity of water changing with voltage ? Never heard that water should have such behaviour !

The infinite resistance at 10cm from the shower shows that it became droplets and that there is no electric shock possible by falling water at this distance.

It has been measured between the metalic case of the shower and a metalic plate placed under the shower.

If you're so sure then just go and wee on the power line of an electric train, as long as your more than 5cm away you should be fine.   

[oldway]

If you're so sure then just go and wee on the power line of an electric train, as long as your more than 5cm away you should be fine.   

Power line of an electric train refering to ground:
France: 25KV 50Hz
Germany - Swiss: 15KV 16h2/3
Belgium - Russia: 3000V dc
Holland: 1500V dc
 

NB: need to login (+ 18a)

[tszaboo]

In case of electric shock, current must be higher than 30mA to be dangerous or even lethal.

Resistivity of water changing with voltage ? Never heard that water should have such behaviour !

The infinite resistance at 10cm from the shower shows that it became droplets and that there is no electric shock possible by falling water at this distance.

https://en.wikipedia.org/wiki/Electric_shock
No, Your resistance changes with the voltage. While with low voltages it is 3Kohm, at 220V it becomes 1.2K. Think of a bunch of triacs which start conducting at higher voltage.
It looks very dangerous.  But now I remember, I used to use something like this when I was young and capitalisms was young. God bless Comecon... not.

Usually installed in kitchens of motels and such. Now, wonder, how safe that thing is?
This is what they have inside:

And the heating element has ceramic insulation to the water. And an electronic controller. And proper grounding, and proper terminal blocks. It costs 60 EUR, now, in the EU, with all the safety requirements!
So please, shower manufacturers: Are you kidding me? Zero effort for safety?

[oldway]

Please read my post with more care...

I am speaking about water resistivity (in ac because in dc you have an electrolyse effect) , nothing to do with resistance of human body.

I did not even take in consideration the human body resistance, only the resistance of the water.

60 euros, that's what a lot of people in Brazil have to live the whole month !

Distilled water is almost an insulator and water with low ionic salts as tap water is a poor electrical conductor

[nrxnrx]

Distilled water is almost an insulator and water with low ionic salts as tap water is a poor electrical conductor

Shocks can be fatal even if you don't die right away. I think I recently saw a post on this forum of someone saying they had arrhythmia until the next day (which fixed itself just before a "manual reset" was tried). Most of my information is anecdotal, so I may be very wrong

At least this thing will never become very old. Someone will stop the water before the showerhead at some point. I wonder how long it takes for 5kW to set it on fire, though the heater may have a weak point* which would melt and keep it an electrical hazard only.

--
Mihai

* not a reliable thermal fuse by any means, but it's the kind of zero-cost addition that may help the designers sleep at night

[oldway]

Shocks can be fatal even if you don't die right away.

I only know 2 ways an electric shock kan kill you: ventricular fibrillation and burning injuries.
The first stop the blood circulation and cerebral dead occur in several minutes.
The second one depends of the extend of injuries.
In the electric chair, brain is cooked in a few seconds.

You need a current greater than 30 mA for alternating current be fatal.

[nrxnrx]

Shocks can be fatal even if you don't die right away.

I only know 2 ways an electric shock kan kill you: ventricular fibrillation and burning injuries.
The first stop the blood circulation and cerebral dead occur in several minutes.
The second one depends of the extend of injuries.

My information on this is anecdotal, but google shows me stuff like this: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC427385/

You need a current greater than 30 mA for alternating current be fatal.

Not across the heart. Wikipedia suggests less than 1mA can kill you. It's not the best source, but there's also a mythbusters episode where they (wrongly!) measured such currents which agrees with me 

I would really like more information on how I and others may die, so if anybody has some information on this, please post!

[oldway]

Wikipedia suggests less than 1mA can kill you.

That's not what Wikipedia say:
"If the current has a direct pathway to the heart (e.g., via a cardiac catheter or other kind of electrode), a much lower current of less than 1 mA (AC or DC) can cause fibrillation."

Nothing to do with electrocution by a shower !

Nb: this kind of electrical shower has been projected and studied by brazilian electrical engineers.

http://www.google.be/url?sa=t&rct=j&q=&esrc=s&source=web&cd=11&ved=0ahUKEwjSnb7txNTKAhVBVRoKHQW3CI8QFghfMAo&url=http%3A%2F%2Fwww.teses.usp.br%2Fteses%2Fdisponiveis%2F3%2F3143%2Ftde-08122006-150201%2Fpublico%2FDissertacao_Claudio_versao_revisada.pdf&usg=AFQjCNE8uPkKPfxD8LOKzbAFUj2dA21cbg&bvm=bv.113034660,d.bGg

It complies also with all brazilians regulations and standards for low voltage electric installations

NB: price of this electric shower: only 10 bucks !

[rsjsouza]

60 euros, that's what a lot of people in Brazil have to live the whole month !

Try to do that fancy heater with 12 Euros, which is what costs a similar chuveiro like this one.

[Zero999]

You need a current greater than 30 mA for alternating current be fatal.

Nonsense.

30mA can easily kill. Whether a current is lethal or not depends on a number of factors including the age, health and gender of the person, the path the current takes and how long it lasts for.

30mA was chosen as a trip point for RCDs because it's highly unlikely a short term exposure would result in any harm. It's also a balance between being safe and nuisance tripping.

Please read my post with more care...

I am speaking about water resistivity (in ac because in dc you have an electrolyse effect) , nothing to do with resistance of human body.

I did not even take in consideration the human body resistance, only the resistance of the water.

60 euros, that's what a lot of people in Brazil have to live the whole month !

Distilled water is almost an insulator and water with low ionic salts as tap water is a poor electrical conductor

Tap water is not de-ionised and its conductivity varies with voltage, as with most non-metals. This was mentioned in the video, if you care to watch.

In addition to a closed element, a thermal fuse and bi-metal strip are needed for fire protection.

The automatic pressure switch is very simple and very secure as the most commun failure is rupture of the rubber pressure disk. In this case, the switch remains open. No risk of fire at all.
Even if the shower would catch fire, this is not that dangerous because there is nothing updown the shower in a badroom that could also catch fire.

In this case, the most common failure mode may be off but switch can and do fail in the closed position and in a humid environment such as a shower head this is more likely than where it's dry.

Thermal fuses don't cost much and if the cheap arse manufacture doesn't fit them they have no respect for the user's life or property.

[amyk]

At least this thing will never become very old. Someone will stop the water before the showerhead at some point. I wonder how long it takes for 5kW to set it on fire, though the heater may have a weak point* which would melt and keep it an electrical hazard only.

If it starts smoking, just turn the water back on...

[oldway]

Nonsense.

30mA can easily kill. Whether a current is lethal or not depends on a number of factors including the age, health and gender of the person, the path the current takes and how long it lasts for.

30mA was chosen as a trip point for RCDs because it's highly unlikely a short term exposure would result in any harm. It's also a balance between being safe and nuisance tripping.

In electrical installations, there are 2 kinds of RCD's, one of 300mA in the mains input intended for protection against risk of fire by leak current, and one or more 30mA RCD's for protection against risks of electrocution.
And you say this is not safe ?
30 mA has been choosen to be a safe limit with no risk of fibrillation. It has never been choosen as a balance between safe and nuisance tripping, but only for safety.
Not every circuit most be protected with 30 mA RCD's, washing machine and dishwasher for exemple are only protected by 300 mA RCD's.

Such a current of only 30mA is also not high enough to produce lethal burn injuries.

I agree that in case of using a pacemaker, 30 mA can be dangerous, but this is an exception.

You must also be aware that very high currents greater than 500 mA does generally not induce fibrillation: that's the reason why electric chair does not always kill at once.

Tap water is not de-ionised and its conductivity varies with voltage, as with most non-metals. This was mentioned in the video, if you care to watch.

Conductivity of tap water vary with temperature, but not with voltage. Of course with dc current, you have another behaviour because you have electrolyse of water, but this does not happen with ac current.
It is a nonsense to say that conductivity of most non-metals vary with voltage. Carbon resistors for exemple does not vary of value with voltage. Only with temperature.
The guy of the video does not know what he is speaking about.

In this case, the most common failure mode may be off but switch can and do fail in the closed position and in a humid environment such as a shower head this is more likely than where it's dry.

The only ways this could happen are:
- welded contacts: this does not happen because current is limited by the resistance. There are also 2 contacts in serie for greater safety.
- broken spring: manufacturers are using inox springs to avoid corrosion failure of springs.

Thermal fuse can't be used because current is as high as 50A in a 110V shower and there is no way to place it reliabily in contact with the resistance. In normal working, this resistance is far hotter than water.
If the shower is working without water, the resistance became at once so hot that it melt and break.

[station240]

What puzzles me, is why they never considered inserting a 12V transformer and making the coil from thicker wire. Would do the same job and be far safer.
Only downside is the weight of the transformer.

Of course if they cared about safety, it would come with a decent length of cord attached for a start, instead of 10cm.

[Zero999]

Nonsense.

30mA can easily kill. Whether a current is lethal or not depends on a number of factors including the age, health and gender of the person, the path the current takes and how long it lasts for.

30mA was chosen as a trip point for RCDs because it's highly unlikely a short term exposure would result in any harm. It's also a balance between being safe and nuisance tripping.

In electrical installations, there are 2 kinds of RCD's, one of 300mA in the mains input intended for protection against risk of fire by leak current, and one or more 30mA RCD's for protection against risks of electrocution.
And you say this is not safe ?
30 mA has been choosen to be a safe limit with no risk of fibrillation. It has never been choosen as a balance between safe and nuisance tripping, but only for safety.
Not every circuit most be protected with 30 mA RCD's, washing machine and dishwasher for exemple are only protected by 300 mA RCD's.

We are talking about RCDs for protection against electric shock here, not fire. What's acceptable also depends on the local wiring regulations. For example, in the UK, all appliances in the house need to be wired to a 30mA RCD, including dishwashers, washing machines and even lighting circuits. The reason for this is because people have been electrocuted before hammering nails into the wall and an RCD provides protection against this.

Such a current of only 30mA is also not high enough to produce lethal burn injuries.

I agree that in case of using a pacemaker, 30 mA can be dangerous, but this is an exception.

But 30mA can kill even a healthy person, if they're unlucky. An RCD will disconnect the circuit before any significant injury occurs but the longer the current flows, the higher the risk. It's Russian roulette.

In the US GFCIs trip at a much lower current (5mA if I remember rightly) but they're typically built-into the sockets so there's only one per appliance, presumably to mitigate nuisance tripping.

Tap water is not de-ionised and its conductivity varies with voltage, as with most non-metals. This was mentioned in the video, if you care to watch.

Conductivity of tap water vary with temperature, but not with voltage. Of course with dc current, you have another behaviour because you have electrolyse of water, but this does not happen with ac current.
It is a nonsense to say that conductivity of most non-metals vary with voltage. Carbon resistors for exemple does not vary of value with voltage. Only with temperature.
The guy of the video does not know what he is speaking about.

The resistance of carbon resistors doesn't vary by much, up to the maximum voltage rating. As soon as this is exceeded by a significant amount, the resistance drops dramatically. Water is no different. You may measure a high resistance between two probes in a glass of water with a multimeter but connect those probes to the mains and measure the current and it will be an order of magnitude higher, than Ohm's law predicts.


If tap water has such a high resistance, than electrode boilers wouldn't exist.

In this case, the most common failure mode may be off but switch can and do fail in the closed position and in a humid environment such as a shower head this is more likely than where it's dry.

The only ways this could happen are:
- welded contacts: this does not happen because current is limited by the resistance. There are also 2 contacts in serie for greater safety.
- broken spring: manufacturers are using inox springs to avoid corrosion failure of springs.

Thermal fuse can't be used because current is as high as 50A in a 110V shower and there is no way to place it reliabily in contact with the resistance. In normal working, this resistance is far hotter than water.
If the shower is working without water, the resistance became at once so hot that it melt and break.

That's what contactors are for. Electric showers here in the UK are perfectly safe. The element is insulated with a ceramic jacket. There's thermal overload protection. The shitty shower discussed here has too many single points of failure to be considered to be safe. Of course it's safe if it's installed correctly, if the switch isn't operated whilst it's in use, if the element isn't broken and if the switch doesn't fail. Too many ifs. It's just not acceptable.

[oldway]

What puzzles me, is why they never considered inserting a 12V transformer and making the coil from thicker wire. Would do the same job and be far safer.
Only downside is the weight of the transformer.

Of course if they cared about safety, it would come with a decent length of cord attached for a start, instead of 10cm.

The most powerfull electric shower has a power of 8500W...in 12V, that's 708A...
They sell this shower for 10 US§....How much is a 10KVA transformer ?

@Hero999: You should try to live in poor countries some years to change your mind.

I took a shower every day during 20 years with this kind of electric shower and I am still alive.

You speak about things you don't know.

And you are almost wrong....I never felt any electric shock with the plastic shower. (with metalic one, yes, but it did not killed me)

Life in Brazil is risky, but not because of those showers.

And in european countries, what kill people is stupidity...It seems that to much security is no security at all.

There is a good reason for this: people think they are safe and does not care anymore with their own security.

In reality, you make your own security, knowing what you are doing and not being distracted or negligent.

How stupid is to say this shower is "suicide" when 80% of the family home in Brazil use everyday this kind of shower ?

You mean there is 180 millions of Brazilians who are suicidals ? 

[oldway]

You may measure a high resistance between two probes in a glass of water with a multimeter but connect those probes to the mains and measure the current and it will be an order of magnitude higher, than Ohm's law predicts.

Measure of resistivity of water MUST always be done in ac.
In dc, there is a polarisation effect that give a wrong value.

[AlxDroidDev]

Life in Brazil is risky, but not because of those showers.

You can say that again... and again... and again....

And in european countries, what kill people is stupidity...It seems that to much security is no security at all.
There is a good reason for this: people think they are safe and does not care anymore with their own security.

Agreed. Too much security gives people excess of confidence, and that's where Darwin's Law steps in. Add to that the fact that people are simply getting dumber - and that's all around the globe. I guess that we, humans, as a race, have already peaked in our collective intelligence, and this was 20 years ago.

How stupid is to say this shower is "suicide" when 80% of the family home in Brazil use everyday this kind of shower ?
You mean there is 180 millions of Brazilians who are suicidals ? 

I can add my 2 cents to this. Showers in Brazil are insecure, but then again, we have very poor - or mostly non existant - building codes. There are regulations (the "NR"s as another Brazilian user pointed out) but nobody follows them. It is a miracle that we don't have more deaths due to house fires, electrocutions and explosions. Nobody here is required to have a certified technician do repairs on their home (or some times of constructions). It's pretty much "anyone can do whatever they want". This entire country is an accident waiting to happen.

You'd be amazed at how many people don't care to connect the shower's earth (green) wire to a properly earth connection.

Even expensive showerheads (that go beyond the US$150 price range) don't add much more security than the basic US$15 showerheads you linked previously. They certainly look a lot better and come in a nice box, but aren't inherently safer.