Earthing for Hot Water Unit

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pal52
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Re: Earthing for Hot Water Unit

Post by pal52 » August 23, 2020, 7:26 pm

dunroaming wrote:
August 23, 2020, 2:34 pm
So other countries have their own standards of safety regulations and don't actually follow the SAA requirements, always been told it's better to be safe than sorry and the difference in price between 4mm and 6 mm is minimal. Sorry forgot to mention I'm an electrical procurement professional with 35 years experience and have never seen 4 mm used for water heaters or showers but you live and learn.
The table Bluejets quoted above is correct according to International (IEE Regulations) & UK standards.
The original question was about Earthing for hot water showers.

It totally depends on the size of the water heater/shower.
Some are 4Kw some 6Kw and even 8kw.

The earth wire only carries fault current for milli seconds if you have the correct sized Circuit Breaker installed.
The cable supplying the heater is rated for continuous current not fault current.

If you buy 4mm cable Twin & Earth the earth conductor is 2.5 mm.
If you buy 6mm twin & Earth the earth conductor is still 2.5mm .

If you want to buy 3 core cable (for 3 phase circuits). you are wasting your money
.
This is an International Standard not just Australia.



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Re: Earthing for Hot Water Unit

Post by dunroaming » August 23, 2020, 7:33 pm

Sorry doesn't just depend on kws also depends on the cable run and what's also connected and men installed but no worries I know what I would install and that's all that matters to me. My friends E&I Engineers not just sparkies along with my brother in law who happens to be an award winning architect don't agree but each to their own. I have no vested interest in this discussion but hope whatever is decided for the OPs installation works

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jackspratt
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Re: Earthing for Hot Water Unit

Post by jackspratt » August 24, 2020, 11:40 am

Thanks guys.

As the HW heater has now been fitted, commissioned, and used successfully, I will return to the thread if or when it turns up its toes.

At that point I will have a better idea if the dual earthing has been a solution to the problem with the previous 2 blowing out somewhat prematurely.

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AlexO
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Re: Earthing for Hot Water Unit

Post by AlexO » August 24, 2020, 5:23 pm

jackspratt wrote:
August 24, 2020, 11:40 am
Thanks guys.

As the HW heater has now been fitted, commissioned, and used successfully, I will return to the thread if or when it turns up its toes.

At that point I will have a better idea if the dual earthing has been a solution to the problem with the previous 2 blowing out somewhat prematurely.
Nothing to do with your earthing systems, probably just planned obsolescence. Manufacturers are not going to build something that lasts forever are they. They need to keep us consumers replacing broken stuff on a regular basis otherwise there comes a time when there is no or very little new sales. Ever wondered why most stuff breaks down just after the warranty period is over. Designed that way!!

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Khun Paul
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Re: Earthing for Hot Water Unit

Post by Khun Paul » August 25, 2020, 8:07 am

JS, in thinking about your OP and after telling what I did to earth, I realised that I too had purchased Panasonic Showers in the past both with built in pumps, both went to the scrapyard in a very short spate of time.
When I purchased this house some 16 years ago there was a Mazuma electic shower fitted, not earthed, ( although it is now ) still operating and working well. The other bathroom has Stiebel Elton shower earthed and working well.
Panasonic in my youth made Hi-fi and the like never a shower, so I drew the conclusion just because you can make a Hi-fi does not mean your good at showers. So although I note your point about earthing, I do not think it made the slightest difference to the shower. As the aforementioned Mazuma was never earthed for over 1o years and had never then nor even to this day broken down some according to the previous owner and myself, some 24 years.

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sometimewoodworker
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Re: Earthing for Hot Water Unit

Post by sometimewoodworker » August 25, 2020, 10:29 am

Matsushita Denki Sangyō Kabushiki-gaisha then Panasonikku Kabushiki-gaisha AKA National, AKA National Panasonic, AKA Panasonic has made and makes a very large variety of products though not selling all in all markets. It is not a Hi-Fi maker making other stuff but a multi product company that has a section that’s is/was the biggest Consumer electronics Producer
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Re: Earthing for Hot Water Unit

Post by bluejets » August 25, 2020, 2:34 pm

dunroaming wrote:
August 23, 2020, 7:33 pm
Sorry doesn't just depend on kws also depends on the cable run and what's also connected and men installed but no worries I know what I would install and that's all that matters to me. My friends E&I Engineers not just sparkies along with my brother in law who happens to be an award winning architect don't agree but each to their own. I have no vested interest in this discussion but hope whatever is decided for the OPs installation works
Whatever load is connected to the cable must come within the ratings of the cable.
So you are incorrect once again.
Architects fyi wouldn't know s**t from clay (to coin a phrase) when it comes to SAA requirements.
Engineers follow a close second.

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Re: Earthing for Hot Water Unit

Post by dunroaming » August 25, 2020, 2:46 pm

SAA regulations mean Jack sh*t here mate we are in Thailand TIT, I have seen showers here connected with 2.5 mm wire and no earth.

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Bandung_Dero
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Re: Earthing for Hot Water Unit

Post by Bandung_Dero » August 25, 2020, 4:12 pm

dunroaming wrote:
August 25, 2020, 2:46 pm
SAA regulations mean Jack sh*t here mate we are in Thailand TIT, I have seen showers here connected with 2.5 mm wire and no earth.
Yep: True statement.

2006 - Next door neighbor building a new two story "upmarket" home on their property for their daughter and Irish husband (both living in Ireland). I was asked to just keep an eye on proceedings, had seen the two HWS installations = NO earth, anywhere and no RCD in the distribution box.

Passed my concerns onto the olde man then to the Irish man. Was ordered to keep my nose out of it by the Thai family - The penny dropped = they and the builder were skimming the funds with sub standard building shortcuts, blatantly obvious by the so called finished home and to this day is a pile of shlte. Disgusted with that and other things the Irish man finished up blowing his nose on it, divorcing then moving to other Asian shores.

2 years later they killed a 9 month old baby grand daughter, in the "new" house, who managed to get her little fingers into one of the VERY sub standard GPO's.

I could go on and on, just about the number killed in our village over the years but flogging a dead horse! [-X
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AlexO
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Re: Earthing for Hot Water Unit

Post by AlexO » August 25, 2020, 7:22 pm

Khun Paul wrote:
August 25, 2020, 8:07 am
JS, in thinking about your OP and after telling what I did to earth, I realised that I too had purchased Panasonic Showers in the past both with built in pumps, both went to the scrapyard in a very short spate of time.
When I purchased this house some 16 years ago there was a Mazuma electic shower fitted, not earthed, ( although it is now ) still operating and working well. The other bathroom has Stiebel Elton shower earthed and working well.
Panasonic in my youth made Hi-fi and the like never a shower, so I drew the conclusion just because you can make a Hi-fi does not mean your good at showers. So although I note your point about earthing, I do not think it made the slightest difference to the shower. As the aforementioned Mazuma was never earthed for over 1o years and had never then nor even to this day broken down some according to the previous owner and myself, some 24 years.
Stick an RCD in line KP I will bet you that the thing will trip after about 20 seconds as the insulation of the heating element breaks down. that fault current is what you are risking your life with. All it needs is for you to make the path then crispy KP.

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Re: Earthing for Hot Water Unit

Post by Khun Paul » August 26, 2020, 6:43 am

All noted however, my system trips in about 1 second from ANY fault in the entire system, in the house and the same in separate circuit in the kitchen block . So I feel secure from becoming crispy , thanks for your concern

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AlexO
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Re: Earthing for Hot Water Unit

Post by AlexO » August 26, 2020, 7:28 am

Khun Paul wrote:
August 26, 2020, 6:43 am
All noted however, my system trips in about 1 second from ANY fault in the entire system, in the house and the same in separate circuit in the kitchen block . So I feel secure from becoming crispy , thanks for your concern
No it does not KP, heating elements are notorious for breaking down through time with the outer sheath expanding and any cracks widening as the element heats up. This can take some time from cold but happens, I suppose your time as a cop and English teacher made you an expert on "any" fault on your electrical system. Stay safe don't get crispy. :-"

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Re: Earthing for Hot Water Unit

Post by glalt » August 26, 2020, 12:11 pm

Much of the wiring in my house is two wire. I'm not a sparky but I know when I get a shock off an appliance. I have five ground stakes around the house. Most of them are for only one appliance. It works for me.

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Barney
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Re: Earthing for Hot Water Unit

Post by Barney » August 26, 2020, 12:48 pm

when I get a shock off an appliance.

glalt
Can you clarify that statement?
Do you physically get a shock or dies your protective CB trip?


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sometimewoodworker
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Re: Earthing for Hot Water Unit

Post by sometimewoodworker » August 26, 2020, 12:52 pm

Khun Paul wrote:
August 26, 2020, 6:43 am
All noted however, my system trips in about 1 second from ANY fault in the entire system, in the house and the same in separate circuit in the kitchen block . So I feel secure from becoming crispy , thanks for your concern
There are different kinds of faults that can occur with electrical installations, some will trip a breaker quickly, some slowly, some will not trip a breaker at all but only a RCCB. 1 second at 80 milliamperes or more can/will stop your heart if passing across your chest (hand to hand) (so many experienced sparkies work with one hand in their pocket.) that is why the trip current on RCCBs is set for between 5 and about 30 milliamperes and is a virtual instant trip (40 ms maximum)
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Re: Earthing for Hot Water Unit

Post by glalt » August 26, 2020, 2:19 pm

Barney wrote:
August 26, 2020, 12:48 pm
when I get a shock off an appliance.

glalt
Can you clarify that statement?
Do you physically get a shock or dies your protective CB trip?


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A physical shock. My computer was very bad for that if I touched a metal part. I pounded in a ground stake beside the house foundation and grounded the computer chassis to it. Problem gone.

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Re: Earthing for Hot Water Unit

Post by bluejets » August 27, 2020, 6:49 am

sometimewoodworker wrote:
August 26, 2020, 12:52 pm
(hand to hand) (so many experienced sparkies work with one hand in their pocket.)
(40 ms maximum)
Electric shock does not need to go hand to hand to put ones heart into fibrillation.
One hand in the pocket is a load of cobblers.
I remember reading an American electrical theory directive once (from the 1950"s)which said the way to test if live is to use the back of the hand.
Nope, also in the cobblers list.

Maximum allowable time for an ELCB trip is 400ms although we will normally chuck them out if over 50ms.
Most will trip between 15 and 40ms with 30mA leakage(standard domestic), 10mA in hospital bedrooms and monitored leakage in operating rooms.

Connection of gear to an extra ground rod may give equipotential but only for leakage currents and what's the point.
If a large fault current arrives, no protection.
Most leckys would consider an electrical tingle as a warning sign and take immediate repair/modification action.
Only last week in Aus, a lecky chose to ignore a similar warning sign because it was not part of his current job.
Sadly he found out the hard way that it actually was his responsibility regardless.

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Khun Paul
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Re: Earthing for Hot Water Unit

Post by Khun Paul » August 27, 2020, 7:38 am

sometimewoodworker wrote:
August 26, 2020, 12:52 pm
Khun Paul wrote:
August 26, 2020, 6:43 am
All noted however, my system trips in about 1 second from ANY fault in the entire system, in the house and the same in separate circuit in the kitchen block . So I feel secure from becoming crispy , thanks for your concern
There are different kinds of faults that can occur with electrical installations, some will trip a breaker quickly, some slowly, some will not trip a breaker at all but only a RCCB. 1 second at 80 milliamperes or more can/will stop your heart if passing across your chest (hand to hand) (so many experienced sparkies work with one hand in their pocket.) that is why the trip current on RCCBs is set for between 5 and about 30 milliamperes and is a virtual instant trip (40 ms maximum)
I agree but the system even immediately shuts down in cases of surges coming plus I have a resetable main breaker affixed to the incoming power . 16 years never had a problem, but switch off main power when playing with wall fittings and unplug before attempting anything. Common-sense in many is in short supply, but it is free

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Re: Earthing for Hot Water Unit

Post by AlexO » August 27, 2020, 5:58 pm

Connection of gear to an extra ground rod may give equipotential but only for leakage currents and what's the point.
If a large fault current arrives, no protection.
Most leckys would consider an electrical tingle as a warning sign and take immediate repair/modification action.
Only last week in Aus, a lecky chose to ignore a similar warning sign because it was not part of his current job.
Sadly he found out the hard way that it actually was his responsibility regardless.

Agree with all your points especially the nonsense about experienced sparkies working with one hand in the pocket.
I might be wrong but sure in earlier days PC,s used the metal frame as a return path for some of the internal electronic circuits. If your system was properly earthed then the small voltage and currents dissipated to earth and no one was any the wiser. However if your system was not earthed (grounded) then 'you' had the chance to become the path to earth, not a full 220/240v shock or in any way fatal but enough to give you a tingle. That's why the additional rod has done the trick. As an experienced spark/engineer of too many years to remember I would highly recommend to all that any electrical circuit that uses electrical heating elements and involves water use a 30mA rated ELCB/ RCD/RCCB/ (same thing just different terminology) as your primary form of life protection.

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Re: Earthing for Hot Water Unit

Post by glalt » August 28, 2020, 10:38 am

Over the past 15 years, I have gone through a number of hot water showers of various brands. When the Hitachi in the house died, I replaced it with a Mazuma. Unfortunately I didn't seal it properly and a jing jok committed suicide. It got in the unit and fried itself along with the circuit board it went under. Since the unit was only about a month old I contacted Mazuma and priced a new circuit board. They replied with a price but told me that if I sent them the heater they would check it out and install a new circuit board for the same price. They repaired the unit promptly and it is now in my game room bathroom and properly sealed. I had replaced the Mazuma in the house with a Panasonic. The Panasonic in my condo is 15 years old and still working so I felt comfortable buying the Panasonic. Both the Mazuma and Panasonic are ELB protected and both are grounded to their own grounding stake. Both are 4,500 watt. I think the Panasonic is better designed because it will heat very cold water hotter than the Mazuma.

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