Shower Water Heater

[ding]

Are shower water heaters being grounded to earth in Thailand?

You can use a 240V GFCI which senses voltage loss on a non-grouded leg ( and assumes voltage is going where it should NOT be going ). This will trip the circuit at 5 milliamps and in 25-40 milliseconds

A.K.A. Residual-Current Circuit Breaker (RCCB) or appliance leakage current interrupter (ALCI).

Or run a ground wire to physical earth so the breaker, fuse, OCPD ( overcurrent protective device ) can referrence ground and trip. But nowhere near as fast, and at high current levels.

[Litlos]

I think you have a bit of wrong information there. The better the earth the better/quicker the GFCI will operate under fault condiions without needing to find an alternative path to earth (possibly you). The heater should include a built in GFCI.

Basically nothing to be gained by not connectting the earth and probably a large improvement in the safety of the system by having it in place.

If it was me the earth would be the first wire conectted and ensuring that the household earth was in good order as well.

Cheers

[Crossy]

Absolutely, it's that green wire at the top.

Note the label that says 'This appliance must be earthed'.

An RCD (GFCI, RCCB) should not be relied upon as the sole form of protection, it is an electromechanical device, they can and do fail. Used in conjunction with a good earth it will however provide additional protection against shock by operating in the event of a L to E fault before any current goes through you. They are usually 30mA here with 10mA for sensitive locations.

By the way, voltage operated earth leakage breakers were phased out in the middle of the last century, they were far too easy to defeat (accidentally). An RCD measures the difference in current in the L and N legs and trips when it exceeds the rated value.

You need a VERY good ground ( < 4 ohms) or a properly configured TN-C-S / MEN system to get your 30A MCB (breaker) to open in a reasonable time.

The correct way is a good ground AND an RCD.

[kdf]

Hello all,

Thanks to some Crossy info I now have an RCD and a much improved ground. I did not do the work myself and we had to get the sparks back several times when we found circuits that were not attached to ground. We are unsure how to test or check items like our hot water heaters for ground, any suggestions? Also our RCD is set at 6, as per Crossy suggestion, but we kept having the switch trip when turning on various items, usually in seemingly random combinations. We have reset the RCD to 30 and it has nearly eliminated the switch offs. How bad is it to run at 30 and any suggestions where to go from here since the respected farangs run company is no longer responding to us?

Thanks

Kdf

[Crossy]

RCD set to 30mA is fine, but if it's tripping occasionally it's worth looking for a fault, something somewhere is a bit leaky.

[TallGuyJohninBKK]

I always love these kinds of threads.... Unfortunately, among my varied talents, being an electrician isn't one of them.

Thus I have little clue about the meaning of most of the electrical terms above. And more importantly, I have NO clue of whom to turn to around BKK who can reliably advise whether our shower heaters are properly/safely configured.

And to make matters worse... I have no green wire at all.... But here's what I do have.

Even if I knew WHAT to do with it, I wouldn't know WHOM to turn to to get it done...

[Crossy]

OK John. The bad news is that you don't appear to have an earth on your heater despite the notice stating that one is required.

The good news is that it has a built in RCD so it is at least reasonably safe, a fact assisted by the casework appearing to be mostly plastic.

It's very difficult to tell where the earth is supposed to connect from the photos, I don't suppose you have the instructions that you could scan? Failing that look for a terminal marked 'E'.

When you find it you must connect it to earth. Either with a green wire back to you distribution box (assuming there is an earth there, better post a photo of that too) or to a local ground rod.

Where in BKK are you, it's a big place

[TallGuyJohninBKK]

Hi Crossy... thanks very much for the reply and info... Yes, the exterior casing of the shower water heater I posted on is entirely plastic. I do probably have the paperwork for the heater around somewhere, but looking around tonight I couldn't lay my hands on it.

I'm in lower Sukhumvit... on the second floor of a 5-story house. As best as I can tell, the main electrical panel with all the circuit breakers and such is downstairs on the first floor kind of underneath the stairwell. The bathroom where the shower heater is located is in a far corner of our 2nd floor unit. I have no clue of what the general grounding situation is for the building where I live, nor what such things would look like.

But the building where I live is owner occupied by several generations of the same Thai family. So it's easy for me to deal with them, and they're generally fine with me making needed improvements or work inside my unit.

Do you have some suggestion of how I can have someone suss things out???

BTW, can you explain, what is the little button titled ELCB checker and what is one supposed to do with it? There's also a little slider piece underneath there that can be moved up and down. Does that stuff have something to do with the power safety issues mentioned above?

Edited March 25, 2012 by TallGuyJohninBKK

[Crossy]

You press the button and the shower should switch off, push the slidey thing to reset.

[TallGuyJohninBKK]

I guess I was asking, what's the point/purpose of that button thing... to demonstrate that the power cut-off circuit is working properly??? So everything is good unless you press the button and the power doesn't go off?

And anything more broadly about how to find someone who knows what they're doing about proper wiring for such things?

[Gary A]

I have a 4,500 watt Hitachi heater. I was very surprised that it has no where to attach a ground wire. I took the copper heating element loose, put the ground wire under the steel bracket that holds it and tightened it back up. It at least has a ground whether it needs it or not.

[electau]

Less than 2 ohms from the earth electrode to any part of the electrical installation in a TN-C-S system for an MCB to operate within the required time, with a TT system an RCD should be installed.

The reasonable time on an earth fault should not exceed 0.4 secs for an MCB, an RCD will operate much faster and must operate at a current between 15 and 30mA.

　

Edited March 26, 2012 by electau

[Daffy D]

Strange there is no grounding point in the heater - never seen that before.

I notice that the incoming black wire is connected to the N - I know TIT and anything can happen but I always assumed the black to be the L wire.

And whats that smaller gray wire coming from the N to the small circuit board with the led?

[ding]

I think you have a bit of wrong information there. The better the earth the better/quicker the GFCI will operate under fault condiions without needing to find an alternative path to earth (possibly you). The heater should include a built in GFCI.

Basically nothing to be gained by not connectting the earth and probably a large improvement in the safety of the system by having it in place.

If it was me the earth would be the first wire conectted and ensuring that the household earth was in good order as well.

Cheers

Not so.

GFCI's measure the difference between non-grounding legs. Common misconception though. But yes, ground the unit for sure.

[ding]

Strange there is no grounding point in the heater - never seen that before.

I notice that the incoming black wire is connected to the N - I know TIT and anything can happen but I always assumed the black to be the L wire.

And whats that smaller gray wire coming from the N to the small circuit board with the led?

The green wire needs an earth ground coming in on the opposite side of the white terminal block. The metal harness strap on the empty side of the t-block is the indication that a branch circuit will enter there.

The MCB that electau talks about is probably a MCCB (molded case circuit breaker). They are slow and even unreliable at times. They protect the wire from overload and ground fault and are resettable. That's about it. Fuses are much safer, trip quicker, only the leg with a fault trips, and fuses protect against arc flash. Use fuses for selective coordination instead of breakers.

The internal wiring -sensing/control- isn't my deal.

[ding]

I have a 4,500 watt Hitachi heater. I was very surprised that it has no where to attach a ground wire. I took the copper heating element loose, put the ground wire under the steel bracket that holds it and tightened it back up. It at least has a ground whether it needs it or not.

Good solution. I thought of a big stainless hose clamp, like on a radiator hose of a car, around the boiler/tank. Squeeze a bare wire under it. I realize there's a dialectric issue but at least it's grounded. Get one that's grounded when it fails eventually, but live to replace it!

[ding]

I always love these kinds of threads.... Unfortunately, among my varied talents, being an electrician isn't one of them.

Thus I have little clue about the meaning of most of the electrical terms above. And more importantly, I have NO clue of whom to turn to around BKK who can reliably advise whether our shower heaters are properly/safely configured.

And to make matters worse... I have no green wire at all.... But here's what I do have.

Even if I knew WHAT to do with it, I wouldn't know WHOM to turn to to get it done...

Isn't it fun when the sticker says it must be earthed (grounded) but there's no provision to ground the unit? At least it has a sticker telling you not to modify the gizzards! LOL

[lopburi3]

I guess I was asking, what's the point/purpose of that button thing... to demonstrate that the power cut-off circuit is working properly??? So everything is good unless you press the button and the power doesn't go off?

And anything more broadly about how to find someone who knows what they're doing about proper wiring for such things?

To insure it is working and has not corroded/soap covered and locked in place (as at least one model no longer sold can). You should test every few weeks just to keep it clean. And it is what will trip if you have an actual fault/cut.

[kdf]

Hello gang,

OK I did not know I was supposed to test the elcb or whatever it is button periodically. Now what exactly is that, some sort of circuit breaker? Any suggestions on how to test how good my new ground is, at the ground rod and/or at the distribution box or other?

One more time for the slow, I have a "safety cut" which I think is something akin to the GFI's I had installed in the US, but works on all circuits run through it. I now have 2 circuit boards, unfortunately with a mix of brands of circuit breakers. One panel has everything go through the safety cut, the other not. All things should be, but I don't know, grounded. After the farang spark master declared our job done, I found several outlets left ungrounded and after getting a shock from an air con compressor unit, got them back to do the rest of the grounding they avoided after beeing paid for the job.

I remain unclear as to what the different values on the safety cut (6,10,20,30 and red) mean to our safety. We were told by the head spark to leave it set at 6, which worked with occasional tripping. Now we must set it at 20 to keep the juice flowing. Assuming I can learn how to test the quality of my ground, what levels are considered safe. I have a digital multimeter, but know how to use only a few features.

We have progressed mightily from the small shocks from metal appliances to fairly frequent safety cut and circuit breaker tripping.

Any and all suggestions are greatly appreciated.

Kdf

[lopburi3]

Yes it is the same type thing as your Safe-t-cut unit made for the shower - and it is good to have the two units as the Safe-t-cut will protect to the unit as well as in the unit itself. The setting should be high enough to prevent trips on the Safe-t-cut but not in the red (bypassed). But even the 30ma is fine. But if you are having trips at that setting you should try to find the cause as something is causing too much leakage. Often a compressor/motor but it can also be poor insulation in a wall outlet somewhere so likely to involve a lot of turn off breakers until next trip (use the 6ma setting to help with this). But if motors it may not happen until they are used/start. There is dedicated equipment for ground testing but for me (non electrician) if I see same voltage for both L/N and L/E believe it is close enough. If you are having frequent trips it sounds as if there is an overload on that/those circuits that you should check for (find out what is causing the trip - perhaps just too many high amperage units on that circuit)

[kdf]

Thanks for the info lopburi3. I will check this out when back from my Songkran escape.

kdf

[Oscar2]

I'll jump on this thread rather than start a new one...

Our Panasonic shower water heater recently developed problems and was leaking. We took it to the Panasonic Repair Center and it still had a year left on warranty. They replaced the entire heating element and thermostat, so it's like new and ready to be picked up today. It is a 3.5KW unit. I got to thinking as I was waiting one month for parts from BKK and for it to be repaired about the safety issues so I decided to investigate.

First, the ground wire goes somewhere up in the attic. It does not go to a proper ground rod. I have no idea where it goes.

Second, the 30 Amp safety beaker is a cheap piece of Chinese junk installed by an electrician here in Chiang Mai.

Third, I never saw the guy that installed it 4 years ago even pull out a meter and check the polarity of the line when he installed the water heater.

So, I went and bought a Hi Tek brand 30 Amp Earth Leakage Circuit Breaker with Short Circuit and Overload Protection for about 225 THB. Most of the breakers available in the shops where all in the 200-300 THB range. The only exception was a brand called Safe T Cut which was about 2800-3200 THB which was out of my budget.

I want to check the polarity and wire the heater properly as I believe the lugs are labeled L and N. Can one of you experts please advise me on this? I have a cheap VOM meter here. What scale or range do I use? There is a V- and a V~ range. I assume I set it to 300V. And what do I test for? I assume I use the black ground probe at the earth ground lug and the red probe to test which of the 2 conductors is "hot" or gives the higher reading. Correct?

As far as safety is concerned, I read in this or another thread that a unit with plastic case is safer than metal. Ours has a plastic case. How concerned should I be about the ground wire not going to a proper ground rod? I have been for the last 4 years checking the ELB once a month and it always functioned properly.

Thanks for your help.

[Litlos]

You should have a GFCI rather than an ELCB as this checks the current imbalance in the circuit rather than monitoring earth leakage, things like a Safe T cut work this way, a much better way of doing things with respect to the Thai supply system. The Safe T cut is probably the best local solution to this. Not sure of your budget, but pretty sure a 3000 Baht good quality breaker has got to be cheaper than the hassle of a dead relative on the premises. Sorry if this sounds flippant, but is a good basic way of thinking about it, prevention is miles better than a cure, and probably cheaper in this case (and/or the long run).

I work with industrial stuff all the time and rarely see plastic, so no real problem here concerning metal and plastic. If from a reputable manufacturer will probably be OK. Chinese are not reputable manufacturers!!!

If you are not sure how to use a VOM or how to interpret the results, honestly, put it away and rely on the test button. That is why the button is there. Not being disparaging, but horses for courses etc. Also less likely you will accidentally connect yourself to something nasty while trying to get a reading that you will probably not understand.

Cheers

[Crossy]

Oscar almost certainly has a current operated RCD / GFCI rather than a voltage operated ELCB which I've not seen for many years (my connection is too slow to load your picture right now).

Get yourself a neon screwdriver, you put one finger on the metal cap and it lights up when you touch the other end to the live wire, reasonably safe (don't drop it in water) and foolproof.

If you must use your meter you should set it to 300V ~ (AC), place one probe on the ground bar (it doesn't matter which), the live wire will read about 220V the neutral 0-10V when touched with the other probe. With a cheap meter I try to avoid holding both probes at the same time, wedge the probe on the ground bar and let go of it, we don't want iffy Chinese insulation failing and connecting you across the mains.

You should check where your ground wire goes, it is a vital first line of defence against shock, the RCD provides additional protection but should not be relied upon as the sole means of protection.

[Oscar2]

Thanks for the replies. I'm sure I can figure out the meter. I was used to seeing "ACV" and "DCV" on other meters but see that V~ is AC Volts - as Crossy said.

I am guessing that the only thing the electrician could have used to connect the ground wire in the attic is the metal frame of the roof. So indeed that is something to consider having properly done ASAP.

Are you saying that the breaker I bought is a redundancy of the ELCB already in the Panasonic water heater? That makes sense what you say about the GFCI. I did not see a GFCI at any of the places I went; Home Pro, Home Mall, Home Expert, etc.

[Crossy]

It's all terminology, different countries call them different things, RCD, RCCB, GFCI, ELCB (old term still used), Safe-T-Cut (actually a brand, and they make other things) are all the same thing.

The roof steel is usually not a bad ground, Google 'Ufer ground' but you really should have a rod too.

I'd rather have the RCD at the board, we have them in addition to the ones in the heaters. The reasoning is simple, an RCD can only protect it's downstream side so the one in the heater will protect against faults actually in the heater, with Thailand's reputation for iffy wiring adding a second unit at the board is good insurance against a taped joint coming adrift or the local fauna making a meal of your cable insulation.

EDIT OK managed to look at your picture. The unit you have although marked 'Earth Leakage Circuit Breaker' is actually an RCBO which combines a 15mA RCD (for earth leakage protection) with a 30A MCB (for overload protection). The input L and N go in the terminals marked 'Line', the terminals marked 'Load' go to the heater.

[lopburi3]

Somehow I can not believe such a unit can be sold for under 300 baht (less than a normal breaker) and was waiting for above confirmation - indeed it does appear to be an RCBO to me also but after buying fake brand name phones in Hat Yai that looked real I would not be betting my life on it. Google was no help on model number or manufacture.

[Oscar2]

It's all terminology, different countries call them different things, RCD, RCCB, GFCI, ELCB (old term still used), Safe-T-Cut (actually a brand, and they make other things) are all the same thing.

The roof steel is usually not a bad ground, Google 'Ufer ground' but you really should have a rod too.

I'd rather have the RCD at the board, we have them in addition to the ones in the heaters. The reasoning is simple, an RCD can only protect it's downstream side so the one in the heater will protect against faults actually in the heater, with Thailand's reputation for iffy wiring adding a second unit at the board is good insurance against a taped joint coming adrift or the local fauna making a meal of your cable insulation.

EDIT OK managed to look at your picture. The unit you have although marked 'Earth Leakage Circuit Breaker' is actually an RCBO which combines a 15mA RCD (for earth leakage protection) with a 30A MCB (for overload protection). The input L and N go in the terminals marked 'Line', the terminals marked 'Load' go to the heater.

O.K. thank you very much. So, just to be clear -- the breaker I bought should be fine? I do not need to go out and search all over for one labeled GFCI??

Hi lopburi3, yes it was 225 Baht at Home Mall in Chiang Mai. I'm pretty sure it is not fake. They have all the name brand items there. Perhaps the pricing was wrong?

Here is the company http://www.thaielect...s/?ID=ID0000006

Here is the product http://www.thaielectrics.com/product/detail.asp?Product_ID=PID0000363

Mine may be a newer model as it looks a little different than the one in the photo. It looks to be good quality craftsmanship.

Edited August 11, 2012 by Oscar2

[Crossy]

It's fine

[lopburi3]

Short circuit and overload protection as mentioned on that photo at above link would indicate to me that it will cut with a dead short (like any breaker should) rather than imbalance between lines. Still looks like a CB with a shorting button.

Perhaps modified to detect a dead short at 15ma rather than requiring the full 30 amps to trip?