Shock from new water heater

[maximus101]

Hi 

I have built a house in Issan  and had it wired to a reasonable standard IMHO

I have a large saftey- cut breaker board and i put the earth rod in myself

Had issues with the electrician so had all connections checked by another commended electricain

had a Mex 5100 watt water heater installed on its own circuit which worked ok until its warranty expired and became faulty and now doesn't work

purchsed a new stiebel eltron 4500 watt unit from Thai Watsadu and installed it and for me was working fine

 

my wife and motherinlaw say they get electric shocks from holding the showerhead (not big shocks but they wont use it)

Contact Thai Watsadu and they send 2 guys out who after the usual claftrap of i need a seperate earth to make it work can find anything wrong

my wife goes to Thai Watsadu and makes a small fuss so they agree to give us store credit as they dont have another of this unit

ok my choices are now much more limited but i found a rinnai 4500 watt unit at makro at a good price and installed it

working ok for me but my wife says she is still getting shocked, its not a big shock as if the she uses a dry hand to hold the shower head she doesnt feel it

 

any advice I am in Issan 45 km from udon thani and happy to pay a reasonable cost for someone who can solve this ( I am still going to shower under it but need to understand what the issue is before my wife will use it

 

Cheers David

PS have one more local guy to come look at it but then dont have many options

 

[Crossy]

Did the local chaps have any test gear? This sort of thing is very hard to diagnose without and the local domestic sparkies really have no clue how anyway.

 

If you fancy a bit of DIY sleuthing and have a multimeter try the below, but only if you feel confident, we don't want you to get fried.

 

======== Take great care if following these instructions =======

 

Firstly ensure (again) the ground is correctly connected and continuous from the shower to the rod, actually measure the resistance don't just follow the wire.

 

Also verify that your supply is the correct polarity at the distribution board, the quick check is with a neon screwdriver, the breaker output should light it, the neutral bar should not.

 

Assuming all is well do you have a MEN connected system (is the neutral connected to the ground in the distribution board)? If you're not sure please post a photo of the distribution board with the lid off (care).

 

Can you measure the voltage (AC) between the electrical ground at the shower and "real" ground, a large screwdriver in the flower bed well away from your ground rod works well. If possible measure with the heater operating (great care).

 

Is the shower upstairs or downstairs?

 

I'm thinking a small (but felt by wifey) voltage between the shower floor (wet and with re-bar close to real ground) and the shower electrical ground, this can occur in a heavily loaded and poorly implemented MEN system.

 

========

 

Notwithstanding the above, there's a huge amount of plastic in modern water heaters, even the "metal" hoses don't conduct electricity particularly well, so it's possible that your good lady just "thinks" she's getting a shock, particularly if it's a mild tingle. It may be an idea to bang in a local rod anyway, it won't make things any less safe and if wifey sees you doing something she may stop feeling the "shock" (you have done what a Thai suggested). Keep the rod as close to the shower area as possible.

 

 

[Thorgal]

Earthing problem + RCD not connected.
Do you have earthing for the shower heater and did you connect an RCD in your main control board ?






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[bankruatsteve]

RCD does not trip on "tingles".  Most are set to 30 mA which would knock you on your ass.   As Crossy points out, it is most likely an earthing situation.  If the hot water pipes are conductive, make sure clamp connection to ground along with the heater.

[tutsiwarrior]

I just had a new shower water heater installed as well...a separate, dedicated earthing arrangement is not 'claptrap' and is required for all of these shower water heaters...make sure you got a little yellow earthing wire from the shower unit attached directly to ground (copper rod in the dirt)...it is not recommended to have your consumer unit (breaker box) earthing arrangement perform this function...

 

 

[Crossy]

7 minutes ago, tutsiwarrior said:

I just had a new shower water heater installed as well...a separate, dedicated earthing arrangement is not 'claptrap' and is required for all of these shower water heaters...make sure you got a little yellow earthing wire from the shower unit attached directly to ground (copper rod in the dirt)...it is not recommended to have your consumer unit (breaker box) earthing arrangement perform this function...

 

Tutsi, please explain your reasoning. Perhaps the whole of the UK, Australia and Europe is wired incorrectly.

 

[maximus101]

16 minutes ago, tutsiwarrior said:

I just had a new shower water heater installed as well...a separate, dedicated earthing arrangement is not 'claptrap' and is required for all of these shower water heaters...make sure you got a little yellow earthing wire from the shower unit attached directly to ground (copper rod in the dirt)...it is not recommended to have your consumer unit (breaker box) earthing arrangement perform this function...

 

 

I dont claim to know all but

my understanding is it is against Thai law (not that matters much) to have more than 1 earth in a domestic installation. please correct me if i am wrong

[maximus101]

Thanks for the replies

pics of installation

 

if i have to i will install a deeper bigger earth wire but i would like to avoid going down the multiple earth route as i dont think it is the right way to do it and not as safe ( I am not an expert on this but it is what i understand from my reading of thai wiring codes

 

I will get the guy who installed the air conditioner to check as he is using the same earth wire and seems to know what he is doing better than most Thais here

 

Cheers

 

 

 

[tutsiwarrior]

31 minutes ago, Crossy said:

 

Tutsi, please explain your reasoning. Perhaps the whole of the UK, Australia and Europe is wired incorrectly.

 

 

dunno...the separate earthing arrangement is indicated on the shower unit installation instructions; ground directly to copper rod, etc...you know, TiT, ghosts and all...

 

will the CU safe - t - cut still work on the shower circuit if the shower unit is earthed separately? I note that all these units have a separate integral ELCB...

 

never seen this arrangement in the UK fer sure...but folks there don't take showers, they take baths...

 

 

Edited January 14, 2017 by tutsiwarrior

[Crossy]

Yes, the RCD (Safe-T-Cut) will still work with a separate rod.

 

And I don't recall the last time I took a bath, yes, I'm a Brit :)

[maximus101]

OK electrician has been and has felt the shock so my wife is not imagining

 

checked everything and all wired correct found some corrosion where earth wire goes into ground

so i purchased a new earth rod and connected = no difference

ran a separate wire to new earth - no difference

 

conclusion from electrician he is getting 12 volt at copper jacket on heater so the machine must be faulty ( huge coincidence that the other unit is faulty as well and both reputable brands)

 

my conclusion after about 7 different electricians who have visited over the last few years none have been able to test an earth

i guess i will have to by one and do it myself 

 

will contact Makro to return and get same electrician to install his reccomended panasonic

 

hopefully we can conclude soon

 

 

Edited January 14, 2017 by maximus101

[RichCor]

I was wondering how all the different heaters could all be presenting the same shock issue.

 

Gotta wonder if there is an issue with differential voltages present on your ground system  ...with the Ground at your Consumer Unit (Breaker Box) floating higher than the actual Ground present in the wet shower. 

 

12v is a lot, but not unheard of.

[Crossy]

What was sparky measuring 12V between? Earth and ... ?

 

[RichCor]

1 hour ago, maximus101 said:

OK electrician has been and has felt the shock [...]

 

[...]

conclusion from electrician he is getting 12 volt at copper jacket on heater so the machine must be faulty ( huge coincidence that the other unit is faulty as well and both reputable brands)

 

I would recommend getting voltage measurements from the copper jacket on the heater to:

 

• Circuit Live
• Circuit Neutral
• Circuit Ground  (should be the same as the jacket if circuit wired correctly)
• Wet shower floor
• Actual wet earth ground (as short a route as possible)

 

Also, what is the size of the Ground Wire in your CU?

 

Also... I am totally confused by the wiring in your CU.  Black and Green mixed on the Neutral bar, White/Gray as Live   ...then your water heater wired in reverse?

Edited January 14, 2017 by RichCor
more specific wire color (white/gray)

[Crossy]

17 minutes ago, RichCor said:

Also... I am totally confused by the wiring in your CU.  Black and Green mixed on the Neutral bar, White as Live   ...then your water heater wired in reverse?

 

We need better photos of the CU.

 

I'm not sure how the supply is routed (is it TT or MEN) and there does seem to be random mixing of N and E 

 

Did the man do a polarity check on the incoming supply?

 

The heater also has a not insignificant lump of plastic between the copper boiler and the hose connection.

[RichCor]

13 minutes ago, Crossy said:

Did the man do a polarity check on the incoming supply?

 

That's another good question.

 

Just got through adding an additional circuit to a friends shop house, where the CU had the incomers wired in reverse so the neutral bar was Live ...and the breakers switching the neutral.

Edited January 14, 2017 by RichCor

[maximus101]

Thanks all good questions and as I dont do work on breaker boxes  (CU) i cant answer and my thai isnt good enough so i have to have my wife translate

Makro has refunded the money (and said they have had a lot of returns of that unit) and we have a local shop installing a Hitachi with 1 year onsite warranty and we dont pay until we are satisfied all is working

 

The electrician? just had a test probe that looked like a digital thermometer no multimeter 

 

will update

 

anyone recommend a testing unit or multi meter i should get so i can test whats happening (I consider myself intelligent enough that i dont know enough to go into Cu except to look)

 

 

 

an hour later

 

New Unit installed and everyone is happy mo shocks

 

The <deleted> installing it pit a a new shower head mount in the wrong place while i was 5 metres away but TiT

 

[RichCor]

There still may be a safety issue with your CU.

Can you take another photo, one as sharp as you can get it?

 

While electricity itself is color-blind, electricians will normally follow a color code so someone else working on your electrical system can do so with better certainty of correctly isolating and terminating the LIVE portion of a given circuit. 

 

The wiring in your CU doesn't seem to be following the established color code, and the circuits may actually be miswired.  A sharper photo of the CU may help us determine if there is a possible critical safety issue that needs to be followed up on.

[tutsiwarrior]

I note from the OP photos that the heater outlet is a metal flex...presumably attached to a metal shower head? what does this say about conductive capability when compared to an all plastic arrangement?

 

does the new heater without problems have all plastic materials on the outlet side?

 

 

Edited January 14, 2017 by tutsiwarrior

[maximus101]

On 1/14/2017 at 10:04 PM, tutsiwarrior said:

I note from the OP photos that the heater outlet is a metal flex...presumably attached to a metal shower head? what does this say about conductive capability when compared to an all plastic arrangement?

 

does the new heater without problems have all plastic materials on the outlet side?

 

 

Yes but it cant be just that as there is no circuit to the chrome casing only path is the water surely

 

I did try and test this earlier but the reply was the wernt using anyway

[tutsiwarrior]

20 minutes ago, maximus101 said:

Yes but it cant be just that as there is no circuit to the chrome casing only path is the water surely

 

I did try and test this earlier but the reply was the wernt using anyway

 

were the metal outlet fittings a modification to the original 'as supplied' arrangement, ie, was the original outlet equipment all plastic?

[maximus101]

22 minutes ago, tutsiwarrior said:

 

were the metal outlet fittings a modification to the original 'as supplied' arrangement, ie, was the original outlet equipment all plastic?

The original shower head and hose were used until the rinnai (2nd replacement) where i used the supplied chrome head and hose, Then the last installer replaced with the supplied plastic one

 

I could put the original back but i dont want to open that can of fish right now

 

I think i have a solution as i have a frriend who is away working as master electrician on a fishing boat will be back in a few weeks i will ask him to have a look

trying to upload a few photos for those who have asked but my internet can be very flakey 

 

Cheers

 

[xylophone]

On 1/14/2017 at 2:30 PM, RichCor said:

Also... I am totally confused by the wiring in your CU.  Black and Green mixed on the Neutral bar, White/Gray as Live  

 

Jeez, have to agree with you RC because that consumer unit looks like an absolute mess and I would bet my bottom dollar that there are a few switched neutrals in that house!