Suicide shower head teardown

[helius]

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

Have a look at this...  If tap water is such a poor conductor, then explain why is there a couple of amps passing through it in this video?

The electrode boiler has two large plate electrodes (~2cm wide and ~30cm long) separated by a tiny gap, about 2mm.
The law for resistivity is R=rho.L/A and ohm's law is V=IR.
240V/2A=120 R; 120R*.006m2/.002m = 360 ohm-m = rho.
360 ohm-m is a very very high resistivity (a poor conductor). It's about twenty billion times higher than copper.
This neglects capacitance, which is also a factor with closely spaced plates and AC.

[nctnico]

I haven't watched the video yet as I'm at work, and I will probably get shot for saying it... but there seems to be a bit of an exaggeration going on here...

I understand your reasoning but to many of us this design is not done for so many reasons. We have learned water and electricity don't mix well and this device just does that. Literally!
Also note the remark about people from Europe (especially the North-West part) being larger. I recall taking a shower in a (not so shabby) hotel in Taipei but I couldn't stand straight in the shower cabin!

[AlxDroidDev]

That I don't think is true in the long term, but it might be true in the short term. It already happened over here during what we call the "middle ages" (~500-1500).

In the 40's, 18yo guys from the US, most of Europe, some from Brazil, Australia, New Zealand and North of Africa, were linning up to go to war and defend their countries against whoever the enemy was in WW2.  Nowadays, 18yo are linning up to watch a justin bieber concert, or to paint their hairs purple, or go on youtube to cry like a bitch when someone offends Brittney Spears. Or youth need to "man up" like our fathers/grandfathers. Compare all forms of art (music, painting, sculpting, and so on) from 40-60 years ago and what it is now.

Have we ever had such great painters as Vermeer, Van Gogh, Rembrandt and Bruegel in the last 30 years, just to name the few from The Netherlands that I know?

Europe has had centuries of headstart in evolution over Brazil, but that's no excuse, since we're about the same age as the USA. Our problem is a historical problem that dates from early in our colonization by the Portuguese. I'd like to tell you all more about Brazil, but I don't think many are interested, and it's way offtopic. If I sound like a skeptic, that's because I am. If our current government keeps on doing what it's doing, we're doomed.

[1xrtt]

.
What about thermal solar for hot water? No dangerous electric showers. No flammable/toxic gas. Just panels with pipes in them to heat water for showering.

Thermal solar is much more efficient for heating water, than photovoltaic.

That is a more affordable alternative. Prices seems to be from USD 700 to 1200. Still, it's not widespread yet, possibly because it also demands some refitting on the water pipes, replacing the typical PVC with copper ones.
Data from our government says that Brazil currently have 5% of households using thermal solar, and the prediction is to achive 24% by 2050! Considering the precision of these estimates, I'd say many Brazilian kids from 22nd century will still shower with the same heads that horrified many in this thread.

http://www.brasil.gov.br/infraestrutura/2015/01/plano-projeta-aumento-no-uso-residencial-de-energia-solar-ate-2050

(translated)
The forecast is that by 2050, 24% of water heating of households is done using the heat of the sun, from the current 5%

[rsjsouza]

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.

That I don't think is true in the long term, but it might be true in the short term. It already happened over here during what we call the "middle ages" (~500-1500).

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.

Having regulations is no guarantee that they're always followed. Generally, they're followed, but there are a lot of examples that they were not and led to problems or accidents.
I used to work for a firm that installs and maintains electrical installations, and I heard lots of stories of the things they found wrong in installations because of ignorance.

I live in a building that still has some asbestos materials in it, some of it will be taken out soon by specialist company which will probably cost many thousands of euros. When researching asbestos, I was surprised to find that its use was prohibited no earlier than 1993! So much for regulations...

Asbestos? Lead? Pfft! Just to give you the amount of ignorance that my other fellow Brazilians are speaking of, time and again we hear stories about people that use Askarel oil stolen from distribution transformers as cooking oil. Not to mention the folks that stole Cesium 137 from an X-ray machine and used it on several places - it glowed in the dark... 

[rsjsouza]

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

Have a look at this...  If tap water is such a poor conductor, then explain why is there a couple of amps passing through it in this video?

The electrode boiler has two large plate electrodes (~2cm wide and ~30cm long) separated by a tiny gap, about 2mm.
The law for resistivity is R=rho.L/A and ohm's law is V=IR.
240V/2A=120 R; 120R*.006m2/.002m = 360 ohm-m = rho.
360 ohm-m is a very very high resistivity (a poor conductor). It's about twenty billion times higher than copper.
This neglects capacitance, which is also a factor with closely spaced plates and AC.

Precisely this. I have done several experiments over the years and can really attest to that - however I learned very early that saying that in public is begging to be laughed at due to the common misconception. The tap water in my home town was a very poor conductor and even the hard water I have here in Dallas is better, but nothing to call home about. That, tied to the much lower resistance path between the resistive element and the ground or between the live and neutral, guarantee that millions are not zapped every day by these chuveiros.

If water was so good of a conductor, why would you die of electrocution if your body was completely wet? Wouldn't electricity flow mostly through the water drops in your skin instead of through your heart?

[MrSlack]

I suspect most people are killed due to poor installation than the nature of the device itself.

[tszaboo]

Precisely this. I have done several experiments over the years and can really attest to that - however I learned very early that saying that in public is begging to be laughed at due to the common misconception. The tap water in my home town was a very poor conductor and even the hard water I have here in Dallas is better, but nothing to call home about. That, tied to the much lower resistance path between the resistive element and the ground or between the live and neutral, guarantee that millions are not zapped every day by these chuveiros.

If water was so good of a conductor, why would you die of electrocution if your body was completely wet? Wouldn't electricity flow mostly through the water drops in your skin instead of through your heart?

Because you are 80% water. And the water at your feet will decrease the resistance to the ground, which is the piping. Ask any electrician, they will tell you that water and electricity is a bad idea. And even if a properly installed shower might be safe most of the cases, they can look like this:

[helius]

Precisely this. I have done several experiments over the years and can really attest to that - however I learned very early that saying that in public is begging to be laughed at due to the common misconception. The tap water in my home town was a very poor conductor and even the hard water I have here in Dallas is better, but nothing to call home about. That, tied to the much lower resistance path between the resistive element and the ground or between the live and neutral, guarantee that millions are not zapped every day by these chuveiros.

Yes, this is certainly true if the device is operating as intended. There is a problem, though, if the resistance heaters were to break off or corrode: the neutral side of the element might be covered in scale and become a poor conductor, or be corroded away by impurities. If the ground wire is left disconnected (which seems common), or it too is corroded, then the only path from live to ground is the user. Even if the ground wire is connected, it doesn't do much to shield the user: it simply pokes into the stream of water. This would be mitigated almost entirely by the use of a sensitive RCD (5mA trigger), but without that it seems too hazardous.

Water quality is taken for granted, but it can be quite variable: as can its conductivity. We have no problems with our water here, but every year when the distribution system is flushed, the dissolved metals go up a lot and it turns brownish. What could seem electrically safe on some days might be dangerous on others.

If water was so good of a conductor, why would you die of electrocution if your body was completely wet? Wouldn't electricity flow mostly through the water drops in your skin instead of through your heart?

The body's contents inside the skin is a very concentrated aqueous solution of electrolytes. Ionic solutes increase water's conductivity a lot. The current that can be lethal to the heart is also very small, only a couple of mA directly. In no way does most of the current need to travel to the heart to cause death.

[rsjsouza]

Precisely this. I have done several experiments over the years and can really attest to that - however I learned very early that saying that in public is begging to be laughed at due to the common misconception. The tap water in my home town was a very poor conductor and even the hard water I have here in Dallas is better, but nothing to call home about. That, tied to the much lower resistance path between the resistive element and the ground or between the live and neutral, guarantee that millions are not zapped every day by these chuveiros.

If water was so good of a conductor, why would you die of electrocution if your body was completely wet? Wouldn't electricity flow mostly through the water drops in your skin instead of through your heart?

Because you are 80% water. And the water at your feet will decrease the resistance to the ground, which is the piping. Ask any electrician, they will tell you that water and electricity is a bad idea. And even if a properly installed shower might be safe most of the cases, they can look like this:

That may be properly installed, but the shower itself is far from being proper...

[rsjsouza]

Precisely this. I have done several experiments over the years and can really attest to that - however I learned very early that saying that in public is begging to be laughed at due to the common misconception. The tap water in my home town was a very poor conductor and even the hard water I have here in Dallas is better, but nothing to call home about. That, tied to the much lower resistance path between the resistive element and the ground or between the live and neutral, guarantee that millions are not zapped every day by these chuveiros.

Yes, this is certainly true if the device is operating as intended. There is a problem, though, if the resistance heaters were to break off or corrode: the neutral side of the element might be covered in scale and become a poor conductor, or be corroded away by impurities. If the ground wire is left disconnected (which seems common), or it too is corroded, then the only path from live to ground is the user. Even if the ground wire is connected, it doesn't do much to shield the user: it simply pokes into the stream of water. This would be mitigated almost entirely by the use of a sensitive RCD (5mA trigger), but without that it seems too hazardous.

Water quality is taken for granted, but it can be quite variable: as can its conductivity. We have no problems with our water here, but every year when the distribution system is flushed, the dissolved metals go up a lot and it turns brownish. What could seem electrically safe on some days might be dangerous on others.

If water was so good of a conductor, why would you die of electrocution if your body was completely wet? Wouldn't electricity flow mostly through the water drops in your skin instead of through your heart?

The body's contents inside the skin is a very concentrated aqueous solution of electrolytes. Ionic solutes increase water's conductivity a lot. The current that can be lethal to the heart is also very small, only a couple of mA directly. In no way does most of the current need to travel to the heart to cause death.

Believe me, water quality varies greatly in Brazil, so much that a common misconception there is that it is not potable (people usually don't drink from the tap, but instead put some "filters" that do nothing more than block residues).

What I discuss is how efficient a "path to ground" or "path to neutral" through one's body would be instead of much lower resistance paths. The galvanized iron connections on drains haven't been used in decades now, as well as the fact that almost 100% of shower stalls are porcelain or granite, which increases the resistance to ground by an enormous extent.

I agree the body and the inner skin are very good electricity conductors, but the outer skin... Not so much. Again, which one would be a lower resistance path?

Look, I think we all understand the common chuveiros are more dangerous than a properly designed water heater, especially considering the quality of the installations around. However, at a certain point in time we must ask ourselves how a red herring this becomes, especially when facing the statistics. Alternatives also have their share of problems: in the past gas was widely used in water heaters, but they are inherently volatile and poisonous (my dad almost died of poisoning while taking a shower). Solar is initially expensive and subject to elements, which increase its cost of ownership (although some folks are reporting the electricity is becoming more expensive, favouring this solution). There is no perfect solution.

(edit: removed a silly sentence constructed)

[vinicius.jlantunes]

Look, I think we all understand the common chuveiros are more dangerous than a properly designed water heater, especially considering the quality of the installations around. However, at a certain point in time we must ask ourselves how a red herring this becomes, especially when facing the statistics. Alternatives also have their share of problems: in the past gas was widely used in water heaters, but they are inherently volatile and poisonous (my dad almost died of poisoning while taking a shower). Solar is initially expensive and subject to elements, which increase its cost of ownership (although some folks are reporting the electricity is becoming more expensive, favouring this solution). There is no perfect solution.

That has been the point I tried to make rsjsouza, but I think some people will disagree no matter what. I too understand and agree that the chuveiro can me made safer, everything can, but the question is: does it need to?

That's where our observations come into play and made me (and you as well it seems) to think that no, it is not really a problem; but others will disagree because their assumptions about what is safe trumps accounts by people like you and me that have used these things for years and live (or lived) in the country where it is widely used. Reality is that there isn't thousands of people dying or getting "tingles" everyday as some people assume in this thread (no matter how tall  ), but people will believe their assumptions more than what we tell them is the reality cause it's part of the complex mechanism happening in their brains that decide what is an acceptable risk and what is not.

There could even be a slight and most probably unintentional prejudice at play, that people in a third world country are so dumb and uneducated that they would not complain about showers shocking them every day - they would learn to live with it and not say a word, or that media and etc. would not report at all if lots of people were dying or being injured as a result of shocks while showering. People keep showing pictures of crappy hostels with obviously crappy installations and seem to assume it's like that in every household, when it really isn't (sure some places it will be, but that is true of any country /system).

(edit: grammar)

[helius]

I don't think the US education system is necessarily better in this regard. Most people here don't see anything wrong with this:
and knowledge of what is and isn't safe doesn't seem to be much better among the trades.

[CatalinaWOW]

I don't think the US education system is necessarily better in this regard. Most people here don't see anything wrong with this:
and knowledge of what is and isn't safe doesn't seem to be much better among the trades.

Again, I will point out that you are only half right.  I agree that knowledge of safest practices is not universal, nor is knowledge of locally accepted definitions of safe practices.

But there is clearly no universally accepted standard for what is safe enough.  Moreover even the components of such a standard are not really available.  What is an acceptable risk of death or serious injury?  One chance in 1E4? on change in 1E6?  One chance in 1E12?  Even the US military, which has a fairly extensive and formal process for dealing with these things only has some general guidelines, and a process for kicking the decision up the command chain as the odds get worse.  And even if you had agreement on that number the data is generally very spotty on what the risks are from any particular activity.

On top of that, your photograph implies a risk which may or may not actually exist.  It might indicate either lack of knowledge about safe practices, or a deep understanding of the risks driving those practices.  For example if the user has a double insulated power tool with ungrounded power cord, but the only available extension cord has a grounding plug, the photographed installation poses no risks that are not accepted by US practice.  It may not comply with the letter of the NEC, but it would not be "unsafe".  Not connecting the adapter to the (potentially ungrounded) screw in the center of the outlet is possibly only a safety precaution to help prevent leaving the adapter in place where subsequent use might involve an unsafe practice. 

[Fungus]

Solar is initially expensive and subject to elements, which increase its cost of ownership

Really?

[rsjsouza]

Solar is initially expensive and subject to elements, which increase its cost of ownership

Really?

This is certainly more expensive than 12 Euros.

[Towger]

This is certainly more expensive than 12 Euros.

No doubt not paid for by the local home owners.

I any event there is no need to heat the water for showers in hot countries.

[Fungus]

This is certainly more expensive than 12 Euros.

Sure, but you get hot water for the whole house, not just the shower. Do Brazilians have cold water in the kitchen or is there another heater for that?

(And maybe hot water for the neighbors house, too...)

[HackedFridgeMagnet]

I have that style of solar Hot water on my roof, it is excellent but it is not cheap.

If anyone has a similar system then I have a tip.
The little vessel mounted on top is the inlet float switch, it should be moved so the inlet pipe to the main tank is not at the top but the side.
This stops the float from having mechanical stress when the tank water is boiling. I learnt this the hard way.

[Fungus]

I have that style of solar Hot water on my roof, it is excellent but it is not cheap.

In some countries they just put a simple water tank on the roof and paint it black to absorb more sun.

[vk6zgo]

This is certainly more expensive than 12 Euros.

No doubt not paid for by the local home owners.

I any event there is no need to heat the water for showers in hot countries.

Australia is (mostly) a hot country,& we certainly do need hot water for our showers.
There is such a thing as Winter.

Even in the Tropical North,a nice hot shower is very enjoyable.

Many years ago,I worked in a town where the water pipes were laid directly on the surface of the ground.
We could have "Hot" showers from the cold tap in the peak of the "Dry" season.
In between the two major seasons,the solar HWS worked well.

In the "Wet" season,the sky could be covered with huge black clouds for days,whilst it poured with rain.
My Employer decided that an Electric booster to the solar HWS wasn't necessary,so I had the great experience of coming  home saturated & covered with red mud,to a cold shower!

[mikerj]

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

Have a look at this...  If tap water is such a poor conductor, then explain why is there a couple of amps passing through it in this video?

The electrode boiler has two large plate electrodes (~2cm wide and ~30cm long) separated by a tiny gap, about 2mm.
The law for resistivity is R=rho.L/A and ohm's law is V=IR.
240V/2A=120 R; 120R*.006m2/.002m = 360 ohm-m = rho.
360 ohm-m is a very very high resistivity (a poor conductor). It's about twenty billion times higher than copper.
This neglects capacitance, which is also a factor with closely spaced plates and AC.

Capacitance will be a negligible effect at 50Hz compared to the conductivity of the water.

You have significantly exaggerated the length of the electrodes in this case.  Unless BigClive has miniscule hands or a enormous pint glass, then the heater electrodes can be no more than about 15cm and probably somewhat less than this.  The electrodes are completely covered, so I don't know how you got the width at 2cm?

360 Ohm.m is a lot higher than copper, but this is completely irrelevant as it is still sufficient to allow a lethal current to flow if the separation is small.  Do you honestly believe this is a safe design?

[Zero999]

Where I live, even light switches in the bathroom need to be pull-cords, so this style of shower wouldn't be allowed, irrespective of whether the element is insulated or not. People must've been killed or severely injured in the past, which is why the wiring regulations exist.

I thought I'd do some resistance measurements on tap water. I compared the resistance indicated by my meter and that obtained by connecting it to the mains, via an isolating transformer and measuring the current. Generally I found my meter was giving double the resistance. The probe spacing made little difference. I tried different meters, a crappy Mastech and a meterman (now Amprobe)  and the results were the same.

The water in my area is fairly hard. Using gold plated banana plugs, about 3cm apart, the meter read 1.25k but the current at 238V was 390mA, giving a resistance of just 611R.

I'm aware this isn't a fully scientific experiment. The lesson is don't trust resistance measurements made with your meter. There's a reason why insulation tests are conducted at higher voltages (120V to 8kV depending on the situation) than normal Ohm meters use.

[vinicius.jlantunes]

People must've been killed or severely injured in the past, which is why the wiring regulations exist.

Ideally the regulations were put in place even before deaths / injuries occurred; I believe that socioeconomic conditions allowing, regulations regarding safety should be tightened as much as possible prior to any deaths occurring. Unfortunately it isn't realistic around here 

[ivan747]

Another country, another way of life and also others rules and regulations.

Safety ? Most of my brazilians friends are dead...in less than 10 years.

How did they died?

shot dead
road accident
poor care in hospital

Only one died of natural death.

There are other priorities in Brazil than safety of showers.

As I measured, at 10 cm from the shower, there is no conduction of water anymore because it became droplets isolated one from the others.

But there is something far more dangerous: the electric water tap.
That's the same as the shower, but there is no isolation more by the droplets principle.

Jeez, that's ugly. Wow. I'd rather have cold water, seriously.

On regards to deaths: even though there are far more apparently important things, details still mater. These details together form a culture. If there is no safety culture:
*Road accidents happen
*Someone gets a bacterial infection on the hospital for ignoring something ridiculously simple, like latex gloves
*Some shoots himself for not using the lock on the gun

You get the idea. Also lacking, in my Dominican experience is: safety, quality of the technical work (this is both the client and the technician's fault), signaling and labeling, and well defined standards and codes (both in law and in practice). Notice I chose aspects related to the topic we're talking about: electric installations and plumbing.

It's a culture that's simply not there. And this sort of culture, in my opinion starts on the details and is one of the things that differentiate undeveloped countries from developed ones. It's not just Gross Domestic Product and export volumes.