Instant Hot Water Heater Blew Up, Billowing Smoke

[onlycw]

This morning, while taking a shower, the HWH starts to burn up inside. white smoke comes out with the stench of people burning plastic.

Failure of electrical products is part of life. But this unit had been out of order. then we called the company technician who claims "nothing was wrong". (Excuse me, but we know how to turn this unit on and whether hot water is coming out after the initial delay and the following 10 seconds...).

Not sure what the guy did. but he got it going again.

Is there a government agency looking into safety issues?

The replacement unit will be one with a long warranty. As cheap can be very expensive in the long run

There should be a fuse inside or something to blow before an electrical fire starts. As this is mass production, I wonder if that technician did any of the infamous short cuts they love to do over here?

Take care,

Chris

[johna]

If it burned I guess it was not grounded. Better see to that with the replacment.

[afarang]

There has been problems with them not being Earthed.A while back a tourist was electrocuted ,due to no Earth being in place.Do Earth them .

[Soutpeel]

The small water heaters prevelant in Thailand are exceptionally dangereous, there should have been a RCB (trip) installed on the unit, which SHOULD throw the power off, which is obviously not the case here, and the units should be properly grounded.

I ditched all the water heaters out my place years ago and installed a proper, grounded water heater to feed the showers, a lot safer than having a power supplies to the heater coming into the bathrooms.

IMHO the small heaters used in Thailand are death traps, and I suprised more people in Thailand are not killed while using them

Long warranties on the units would be the least of my worries....

[dogleg]

We had a MAZUMA unit a year ago. Managed to repair it a few times by replacing extremely poor quality internal wiring and connectors, after insulation and plastic cover melted in a few places.

I looked at later models when it came to replacement time and they looked 'better' quality internally but I'd had enough of MAZUMA. They aren't cheap either!

[jaideeguy]

People do die from them here.....wife tells me of a [used to be] famous Thai actor that fried in the shower from a hot water heater that was not grounded.

[powderpuff]

Problem is not a lack of a ground. Problem is a lack of an ELCB.

Apparrentley your house is not protected by a Saf-T-Cut either. Playing with fire.

[metisdead]

Moved to Do it Yourself Housing forum.

[lopburi3]

Neither a Safe-T-Cut (RCCB) or a ground is going to protect from many plastic melts. There does not seem to have been any explosion or people burning involved. Plastic normally melts due to loose/bad connections causing local sparking/high temps and unless going to ground there will not be any imbalance for the RCCB to trip on and until the current gets high enough the circuit breaker will not trip either.

Edit: as this is the coldest season wonder if the feed wire is large enough? You are likely using the full 3.5k of heating this time of the year.

[transam]

As it's a biggish wattage user, If there is a loose connection, say a spade connector, the joint will get hot and the heat transfer will melt the wire covering which will give off white smoke and smell of burning plastic.

[steelepulse]

Problem is not a lack of a ground. Problem is a lack of an ELCB.

Apparrentley your house is not protected by a Saf-T-Cut either. Playing with fire.

A friend of mine had his son electrocuted in his shower a year ago Christmas. I asked his very good friend yesterday if they ever found out what happened, and the contractor changed the type of breaker that is necessary and that's what caused the accident.

[powderpuff]

To the OP.

Yes what you had was cheap.

btw - what is this "people burning" nonsense?. Something to do with skin?

It is no good whining about the government coming in to save you. By now you know there is close to zero "code" & there are no inspectors running around behind these contractors to insure a non existant "code" was followed.

If you get electrocuted there will be nobody to sue.

So at the end of the day it is up to you to insure your house wiring is safe.

If you have to hire your own engineers - well what is a life worth?

You now live in the third world. Far far above some places like Africa. Lest ye think I am Thai bashing - I am not.

[Pib]

Remember, that although you many see a lot of "Safety First" signs in Thailand, it's just a slogan with little substance behind it, especially when it comes to construction and electrical work. Also be sure watch out for the Safety First signs in Thailand because sometimes they are misplaced causing a safety hazard.

[thatguy]

OP stench of people burning plastic

PP btw - what is this "people burning" nonsense?. Something to do with skin?

as no one else explained it:

did bring a chuckle first read, delete "people", or substitute "someone"

[trogers]

Had a Stiebel instant water heater shorted over 3 years ago. The cause, a lizard crawled into it and got fried and shorted out the internal wiring/contacts. Replaced it with a Panasonic since.

[doglover]

Had a Stiebel instant water heater shorted over 3 years ago. The cause, a lizard crawled into it and got fried and shorted out the internal wiring/contacts. Replaced it with a Panasonic since.

Geckos don't like to crawl around inside Panasonics?

[doglover]

Neither a Safe-T-Cut (RCCB) or a ground is going to protect from many plastic melts. There does not seem to have been any explosion or people burning involved. Plastic normally melts due to loose/bad connections causing local sparking/high temps and unless going to ground there will not be any imbalance for the RCCB to trip on and until the current gets high enough the circuit breaker will not trip either.

Edit: as this is the coldest season wonder if the feed wire is large enough? You are likely using the full 3.5k of heating this time of the year.

I am under the understanding that Safe-T-Cuts and the ELCB (if there is one) inside the hot water unit trip when they detect an imbalance between the hot and neutral conductor and not the hot OR neutral and earth/ground conductor. So I am thinking that if the hot or neutral was loose enough to create arcing this would provide the imbalance to trip as the heat given off is lost energy and an imbalance between what is supplied and returned.

[Crossy]

I am under the understanding that Safe-T-Cuts and the ELCB (if there is one) inside the hot water unit trip when they detect an imbalance between the hot and neutral conductor and not the hot OR neutral and earth/ground conductor. So I am thinking that if the hot or neutral was loose enough to create arcing this would provide the imbalance to trip as the heat given off is lost energy and an imbalance between what is supplied and returned.

You are nearly correct. An RCD will trip if there is a difference in the current flow in the L and N conductors, this would be caused by some of the current going via an alternative path (you) to ground.

In the case of a loose / arcing connector the current doesn't take an alternative path so an RCD won't trip.

[doglover]

Thanks for the clarification Crossy. If you get the time a response to my last post under "Need Qualified Electrician" started by the Swiss gentleman would be greatly appreciated. If I am barking up the wrong tree I would like to know as well.

[jombom]

On my shower unit, it is labelled ELB. I always check these, when staying in a new hotel etc, by pressing the Test button, and they always trip.

However, I think this test is only testing the spring, and not actually testing the Earth leak response. Is there a simple way of checking ??

[Crossy]

On my shower unit, it is labelled ELB. I always check these, when staying in a new hotel etc, by pressing the Test button, and they always trip.

However, I think this test is only testing the spring, and not actually testing the Earth leak response. Is there a simple way of checking ??

If it's a correctly designed unit, it does actually test the earth leakage detection

[Forkinhades]

Ah another shower question.

With the arrival of my little boy 15 months ago, I decided to get my house rewired with an Crabtree dual RCD distribution board, with 3 circuits on mcb's for security and alarms. However the 'electrcian' did not rewire the shower unit which was 8kw fed by 2.5mm cable. As the cable was too small arcing was present, and a small weld began to develop, and over a period of time this weld eventually went down to earth. Luckily the RCD on the new DB tripped, but not the ELCB on the shower!!! , which could have been potentially fatal. I would not trust these ELCB on the shower to work, indeed especially in the time required to prevent serious electrical injury or death. These units need to be tested with the proper equipment, by applying a fault current to make sure they trip within 400 milli seconds. Forget about pressing the button the shower unit, as they are probably just a switch and not an ELCB.

pm me if you need more details.

[Forkinhades]

Thanks for the clarification Crossy. If you get the time a response to my last post under "Need Qualified Electrician" started by the Swiss gentleman would be greatly appreciated. If I am barking up the wrong tree I would like to know as well.

could you please provide a link to the post

[Crossy]

Thanks for the clarification Crossy. If you get the time a response to my last post under "Need Qualified Electrician" started by the Swiss gentleman would be greatly appreciated. If I am barking up the wrong tree I would like to know as well.

could you please provide a link to the post

This one

Also, regarding RCDs, they can only protect circuits on the controlled side, so a problem in the cable feeding the shower will NOT trip a unit built in to the shower.

I agree with FinH, by far the best protection is provided by an RCD in your distribution panel.

[lopburi3]

Forget about pressing the button the shower unit, as they are probably just a switch and not an ELCB.

Please do not forget to test that switch occasionally. It is there for a valid reason. It will not protect from faults prior to input of shower but should protect for shower faults. I have had one fail due to soap scum buildup (old model since re-designed) that CB was physically prevented from trip. The main home Safe-T-Cut saved a life in that case.

[merijn]

Problem is not a lack of a ground. Problem is a lack of an ELCB.

Apparrentley your house is not protected by a Saf-T-Cut either. Playing with fire.

A friend of mine had his son electrocuted in his shower a year ago Christmas. I asked his very good friend yesterday if they ever found out what happened, and the contractor changed the type of breaker that is necessary and that's what caused the accident.

I think we are thinking about the same boy who died in the shower last year christmas.

I did not know that the contractor changed the breaker type.

After this accident i changed all my heaters in my house for proper quality ones.

[Pib]

Well, my Fagor 6000W water heater died tonight right when I began turning the hot water off. You could see and hear a flash/short occurring through the hard plastic case and then its power-on indicator went off...stayed off even when I turned the hot water control back on. The wife was downstairs at the time and said she heard a very brief "whine-like sound" but didn't know what it was. That sound was probably coming from the main circuit breaker box about 15 ft from where she was at, and the sound was probably caused by the breaker as the electricity surged very briefly, probably as the heating element within the heater burnout....kinda like the filament in a light bulb burning out. Have you ever noticed when an incandescent bulb burns out...many times it flashes brighter for a split second then it's dark/dead. The circuit breaker for the heater is a 32 amp as required for a 6000W heater....that's why I chose a 6000W heater since my bathroom heater wiring/circuit breaker was a 32 amp setup. Checked the breaker with my trusty multimeter and it's still good. I know some may think, "Well, the circuit breaker should have popped." Not necessarily. I had just started to turn it off when the heater died, so he heater was was still pulling normal current (around 27 amps for 6000 watts on 230 volts) and I think the heater element just burnt out very quickly like a light bulb filament and pulled a few milliseconds current spike...spike wasn't long enough to trip the circuit breaker. Even circuit breakers can't trip fast enough to keep a failure like that from occurring. But I still may change the breaker. My heater is made by Fagor (German made) and has a 3 year warranty...the heater was 2 yrs 4 months old...will be calling the Fagor Customer Service number in Bangkok on Monday morning.

[Forkinhades]

^ how did you test the MCB with a multimeter??

[Pib]

When I say test the circuit breaker, I really just meant a basic test of ensuring voltage was still getting through it when turned on and no voltage getting through when turned off.

I pulled the case off the heater this morning (real easy to do)...every thing looks fine inside...in fact, looks brand new to tell you the truth. It was wired corectly with a case/earth ground. Fortunately, my home was built/wired with 3 wires, which includes a earth/safety ground wire. I guess the flashing I saw was just the power LED. Checked to make sure 230V was getting to the unit with the CB on...and no voltage with the CB off. I expect one or both of the two 3000W heating elements opened up/burnt open and some internal fusing has shut the unit completely down. The manual mentions some fast reaction thermal fuses inside the unit....I expect one or both of these blew also...blew faster than my CB could trip. As mentioned, at this point I'm guessing one or both heater elements has burnt open/failed...basically the same thing that happens to the screw-in water heater elements for the tank water heaters like used in many western countries...on my last such tank water heater I had in the States it seems about every 3-5 years I had to change a heating element as the element inself would corrode...a few drop of water would get into the part of the element carrying power, and BAAMMM!!!, you have a shorted element that usually trips (not always) the circuit breaker in the panel, but always tripped the breaker in the tank assembly. Fairly easy to replace if not corroded...cut power...drain the tank...removed electrical connections...uncrew element...and then reinstall/reconnect wires...refill tank...flow water for a minute or two to ensure the tank is really full...and then turn power back on (including reseting the breaker in the tank which is usually a push button type)....good for X-amount more years.

But back to my current Fagor heater problem, I didn't get into ohming-out the elements...didn't want to try to pull the connection wires off so I could do a good ohm test or check a few other flow & thermal fuses in the unit....I may have ended up messing up a connection and when the warranty/repair guy comes out tomorrow he could have seen someone messed with the heater as how else could the connection got broken. No warranty void if broken seal on the case so they will never know I have peaked a looked inside already. When an item is still under repair it can make a person not do additional tests especially when you know there is nothing additional you can do to affect a quick & easy fix...plus, the warranty repair guy will arrive in a day or so. But by opening the case I did get to see how the looped heating elements are just sandwiched between the tubes carring water versus screw-in type elements in a large tank heater where the element is actually inserted into the water. Called the Fagor customer service folks around 8:35am this morning...they are suppose to call back today to confirm an appt/repair time for tomorrow. Until then, it's just a cold shower (oh, the horror this time of year!!!) or use the other bathroom shower.

[Forkinhades]

^ It sounds like you had a direct short between phase and neutral, probably on one of the elements, thats why the MCB tripped, if it was an earth fault then the in built ELCB should have operated on the shower. Sounds like they both tripped, which is good.

Just because your house has 3 wires with an earth, the earth still needs to be good quality, whether supplied by the PEA (unlikely) or an earth rod, and indeed if you have only protection by MCB's then the earth needs to be tested to make sure that reading is LOW enough, in order for the MCB's to trip in time, if you have a high value earth then under phase to earth fault conditions your MCB's will not rip in time to protect against electric shock.