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Topic Title: [Slightly OT] South American style shower head dissected
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Created On: 22 January 2016 09:04 PM
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 22 January 2016 09:04 PM
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TimJWatts

Posts: 390
Joined: 07 August 2013

Having taken so much from this forum, and not really being in a good position to offer much back - I thought some folks might find this interesting:

Shower head dissected

Whilst everyone's knows of this type of shower heater, the video and Clive's commentary is really interesting - it's both clever and disturbing on so many levels.

Perhaps a little perspective on AMD3

Cheers, Tim

PS - No I'm not making a habit of this type of posting!
 22 January 2016 09:21 PM
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nad

Posts: 396
Joined: 14 January 2005

Thanks Tim,

I'm trying to get my head around the earth connection to the water spray.. interesting.

-------------------------
Nad

*Regularly edited due to spell cheque misdiagnosis
 22 January 2016 10:11 PM
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TimJWatts

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Originally posted by: nad

Thanks Tim,



I'm trying to get my head around the earth connection to the water spray.. interesting.


I believe it is supposed to collect any electrical leakage... Which a few comments BigClive made are particularly interesting:

a) I think he mentioned it wasn't stripped originally so didn't do that much;

b) If you have an RCD things might get interesting;

c) Lots of places don't bother connecting the earth. I will ask my mate - he spent some time in Bolivia and will probably have seen these.
 22 January 2016 10:24 PM
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Zs

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Tim,

When I went to Honduras and Guatemala a few years' back to do some voluntary work, they had those shower heads except that the electrical connections were connector block just above the unit and in the water spray. Screwits.

I washed in the shower enclosure using a bucket of water for all the time I was there.

I cannot remember the Spanish words which they told me when I looked on in horror but they translate to English as 'Widow makers'


the one I got to use in Vanuatu, which had been installed in expectation of the 'Deity' Prince Philip incidentally, was even better I told them I drive past his house once a month or so and got upgraded to 'his' mud hut you see.

Great post.

Zs

Edited: 22 January 2016 at 10:32 PM by Zs
 22 January 2016 11:47 PM
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AncientMariner

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Back in the 1980's I fitted a 6 kW electric shower for my in-laws. (No Part P then, you simply filled in a form and the local Electricity Board would come round, inspect and connect the new switch-fuse to their meter.)

Anyway, on fitting I was a bit surprised to see that the heat exchanger was a clear acrylic(?) block with various drillings for waterways, there being both Hot and Cold taps beneath the unit as a form of mixer. With just 6 kW you did not need much cold...

Within the drillings in the acrylic block were elements. not sheathed just simple resistance wire in a 5mm coil.

Interestingly there was a sort of earth connection within the water flow where the water exited the block.

I remember not being happy with the leakage resistance - the heater block was still wet from its manufacturers test.

So when the MANWEB guy arrived I asked him what he thought. His view was that the insulation resistance would improve once the shower had been used.

I cannot remember the make, it may have been Redring, but it lasted for some years until we moved in and replaced the bathroom in 2003. The bath was cast iron and connected to earth, as were the bathrooms pipes including the lead bath and basin waste.

I never felt any tingle when I used it, nor did anyone else! Amazing!

Cheers!

Clive

-------------------------
Clive S Carver GCGI IEng MIET MITP
 23 January 2016 01:07 AM
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mapj1

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Very common design in Brazil, where despite it being regulation, it is most unusual to find a circuit CPC anywhere, so the green wires just get snipped off.
220V 60Hx in the south, 110V 60Hz in the north - but the same connectors, so take great care to fit the right model..
The saving grace is that the plumbing is almost exclusively plastic, so you and the shower tray just get livened up together and actually no great current flows . Didn't ever see an RCD in a domestic property while I was there either.
It is not as dangerous in practice as it looks, unless the top cover comes off in your hand while fiddling with the temperature switch - which is then a bit un-nerving .

16kohm cm is not especially high spec, (a megohm cm is laboratory pure ) but as he notes it is best measured with about the right voltage and AC, as you get strange polarising effects due to electrolysis with DC tests. I can imagine problems if the water system is ever flushed with any kind of de-scaler.
Given the aggro I have had with trying to deliberately earth the water on laser cooling systems, I'd prefer to see the water pass via a short length of earthed metal pipe - the cm or so of wire end does not really look like enough to me, but as its never connected up anyway its academic.. (On the lasers we dropped about 500V of rectified 3 phase across a few feet of plastic half inch hose, but until we got it right, we were pouring noticeably live cooling water down the drain.)

-------------------------
regards Mike
 23 January 2016 10:26 AM
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nad

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Was thinking about the earthed water spray and wondering if UK electric showers do the same. I've installed a few of them and never seen such a connection (could be internal though I thought).

Was then wondering what would happen if showering whilst there being the dreaded PME lost neutral fault on the supply.

But if I follow Mike correctly a bonded copper water pipe supplying, the shower would behave similarly?

I suppose the earth to the shower also makes contact with the water through the copper internals within the shower enclosure.

-------------------------
Nad

*Regularly edited due to spell cheque misdiagnosis
 23 January 2016 10:10 PM
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sparkingchip

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Aren't the issues the same as with a electrode boiler as covered by section 554.1 of BS7671?

Andy
 23 January 2016 11:02 PM
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sparkingchip

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There are photos of some better looking units as well.

Green Building
 23 January 2016 11:40 PM
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mapj1

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yep, that's not my foto, but I have several very like it, usually the side shower tail is long enough to reach the middle of the shortest user - you get the idea - but that top cover not clipped properly on top and poised to drop off when you operate the side switch is depressingly typical)
You get used to twist and tape singles hanging out the wall for any fixed appliance after a while (sometimes only tape on the live), and then you return to the UK and it all seems a bit OTT here when for some random reason you can't have an RCD protected 13A socket in the bathroom.

Because weirdly, their electrical accident figures are not massively worse than ours. The locals I met however were much more careful than we are about keeping kids away from wiring and generally turning stuff off when its not in use. It seems that behaviour compensates for safety measures to a large extent.

-------------------------
regards Mike
 24 January 2016 11:39 AM
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nad

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Originally posted by: sparkingchip

Aren't the issues the same as with a electrode boiler as covered by section 554.1 of BS7671?



Andy


Hello Andy,

Having just read that section- I'm still not sure. I must confess I didn't know what an electrode boiler was, thinking it was the same as a water heater with an immersed electric heating element, until I read 554.3.

The Regs treat these types of heater differently. As I see the electrode boiler requires a double pole linked CPD to disconnect the neutral on operation. Whereas the immersed element water heater doesn't.

There are other differences too. The regs seem much more onerous for electrode boilers. I guess by nature of current passing directly through the heated water- I wouldn't want to shower under one.

Reg 554.3.2 looks like it covers my last post.

Thanks,

-------------------------
Nad

*Regularly edited due to spell cheque misdiagnosis

Edited: 24 January 2016 at 11:46 AM by nad
 24 January 2016 12:29 PM
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perspicacious

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Andy

Shirley you must remember the aquatic marine mammal branded showers/bathrooms company who used to trade from Bromwich Rd WR2 4BD whose speciality in the 70/80s was an 8? kW uninsulated heating element immersed in water, the specific Regs are still in 554.3?
Care was taken to ensure that the N end of the element was at the outlet end. Somewhere in my collection I've got a sample see through block of the element surrounded by water. Quite a few issues with installers not running an independent cpc......

Regards

BOD
 24 January 2016 04:16 PM
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sparkingchip

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You have got me thinking now.

I have seen a number of their installations where the showers have been replaced with the circuit being reused and noted that they ran a main bonding conductor to the shower and pipework within the bathroom.

I always assumed it was just to ensure the pipework installation is earthed in general, are you now telling me it was a specific requirement for the type of shower they were installing?

Andy
 24 January 2016 04:24 PM
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perspicacious

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Yes it was only done for their (unique?) immersed uninsulated element but I believe that they stopped using this type mid 90's to make the same as the other shower manufacturers.

You can rest easy now you know what the extra cpc was for

I can remember their technical manager being a very pleasant chap who had an interest in being a pilot.

Regards

BOD
 24 January 2016 04:27 PM
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sparkingchip

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 24 January 2016 04:33 PM
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sparkingchip

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Originally posted by: perspicacious

Yes it was only done for their (unique?) immersed uninsulated element but I believe that they stopped using this type mid 90's to make the same as the other shower manufacturers.



You can rest easy now you know what the extra cpc was for



I can remember their technical manager being a very pleasant chap who had an interest in being a pilot.



Regards



BOD


Some years ago I attended the two day Triton shower installers course at their factory, it is sufficient to say they did not cover the use of showers with uninsulated heating elements!

Andy
 24 January 2016 04:45 PM
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sparkingchip

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 24 January 2016 05:00 PM
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TimJWatts

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Originally posted by: sparkingchip



There are photos of some better looking units as well.

Green Building


OMG...
 24 January 2016 05:11 PM
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sparkingchip

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It's a funny old world, I am sat on the settee half watching James Bond on a Sunday afternoon and Googled images of electrode boilers.

A image came up linked to the former head of the electrical department at the college I attended to do my City and Guilds for three years of evening classes around fifteen years ago.

I guess at some point in the three years he told me about electrode boilers, but it has slipped from my memory over the intervening years as not being relevant to any work I have undertaken.

Andy

Edited: 25 January 2016 at 06:39 PM by sparkingchip
 24 January 2016 05:57 PM
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nad

Posts: 396
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Originally posted by: sparkingchip

Yes Nad you right.



Back to Big Clive for a demonstration



Andy


Thanks, that's not something I hear very often.

Am really enjoying Big Clive's demonstrations but found this one difficult to watch- especially when he dropped the teaspoon in!

-------------------------
Nad

*Regularly edited due to spell cheque misdiagnosis
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