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BANGKOK 25 April 2019 19:25
ozbanglamung

Fried Circuit Breakers.... Help

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Can somebody please advise me on what may have caused this (seer attached pics).. It was attached to a HW Heater.  I have another with the same issue but I am not sure what it was attached too, I think probably the other water heater. There are three that have been destroyed, one of them was burned by the one that  burned out below it. Its a bloody miracle the house didn't burn down. Now the circuit breakers are a mix of Shneider as you can see in the panel pic. I am not  sure what the difference is between C16, C20 and C32 and what should be attached to what, but I assumed that C32 was the strongest so I had a spare and attached the HW heater to it and tested it. I let the hot water run for ten minutes then pulled the breaker out. It was warm to the touch but onlu just warm,  but by no mean   anywhere near what would be required to melt it. So I am at loss to know what caused it. I was just about to go down and buy a couple more when i noticed these different numbers so I thought I should better ask. Thanks for your help in advance.  

 

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I just remembered something I should probably add, The house was hit (literally and it frightened the crap out of me)  twice by lightning during a storm about six months ago. Some strange things happened to the circuit breakers then, Nothing was tripped but I lost power to all the power points in the master bedroom. The next day I had a look at the breakers and there was a spare with nothing attached to it and it had this red light on it. So being the electrician that I am, (not) I went and bought a new one and plugged it in then the bedroom was ok. Now remember this breaker had nothing attached to it so the short answer is NFI what happened there but I guess the strikes could have been the beginning of the end for the two water heater breakers and they took a while to burn out because they only cook up when somebody has a shower. Anyway, back to the main program 

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Posted (edited)
1 hour ago, Crossy said:

That looks like it was a loose connection that's been fizzing for a while. You should be able to replace with the same type with no issues.

 

Check all the other connections are tight (power off of course).

 

Agree with Crossy; also..............what size are the water heaters, in watts? These breakers MAY be a little light if the heaters are hefty buggers!!

Edited by xylophone
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Just now, xylophone said:

Also..............what size are the water heaters, in watts? These breakers MAY be a little light if the heaters are hefty buggers!!

 

Indeed, but as STWW notes, the breakers are there to protect the cable, so a bigger cable may also be on the cards. 

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13 minutes ago, Crossy said:

 

Indeed, but as STWW notes, the breakers are there to protect the cable, so a bigger cable may also be on the cards. 

Could be the case, but from what I could see on the pic the cable size for that breaker looked bigger than 2.5mm and was poss 4mm, so whilst the cable could be ok, the breaker could be 'light" for a high rated heater???

 

Whereas the cable could stand operating near its capacity for short durations, quite easily?

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Thanks for the replies guys. The water heaters are 6000W. The cables for the water heaters are the fatest black ones. now the fact is i could well be responsible for this cock up as I did  not know that the number protects the cable. In fact until i looked at that pic today I did not know there was more than one number and I could well have moved a water heater to the twenty when it may well have been attached to the 32 few months ago when I replaced a whole bunch of light switches.  Today i made sure both water heaters were on 32's because I thought bigger is better ( I know i'm a dumb ass) and then tested it for ten minutes as stated !!! Simply amazing I am still alive to be honest. It all seems to be ok now although one of the air conditioners would not turn off either with the remote or by pressing the power button on the unit, I had to turn the breaker off to shut it down but that is probably another issue and muddying the waters. So the 32's would be for water heaters and aircons ? I have a shit load of stuff going through that board, my bill averages 8000 baht a month and no that is not a mis type !!

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If cable is rated for the current, as another poster said, good idea to check connections.

Breakers should not melt.

They should break before they melt if it's been a matter of high current demands. 

Lightning strikes can blow things apart but seems like poor dirty connections is the culprit this time or a bodgy breaker or 3.

Try a different brand of breaker for replacements.

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thanks stud 🙂 well i managed to burn pretty big holes in two of them. and as far as poo/dirty connections goes the idiot that wired my house has used red, white, black and blue wires wherever he felt like it and there is not an earth wire within miles of any powerpoint in this house. I will pull all the breakers off and have a good look at them. One of the pics of the board in close up shows they are in pretty poor condition i think, and the house is only three years old

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8 minutes ago, ozbanglamung said:

thanks stud 🙂 well i managed to burn pretty big holes in two of them. and as far as poo/dirty connections goes the idiot that wired my house has used red, white, black and blue wires wherever he felt like it and there is not an earth wire within miles of any powerpoint in this house. I will pull all the breakers off and have a good look at them. One of the pics of the board in close up shows they are in pretty poor condition i think, and the house is only three years old

Take it slow. Make sure you are not playing with live wires. Be certain and work with a friend along side who is not distracting you but enforcing safety.

Should be a main breaker and check with a multimeter for voltage to make sure Meter is working and then without voltage to show 0 reading. 

I hate the higher voltage stuff cause my brain is like a zombie these days.

B safe.

 

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Posted (edited)
10 hours ago, ozbanglamung said:

Thanks for the replies guys. The water heaters are 6000W. The cables for the water heaters are the fatest black ones. now the fact is i could well be responsible for this cock up as I did  not know that the number protects the cable. In fact until i looked at that pic today I did not know there was more than one number and I could well have moved a water heater to the twenty when it may well have been attached to the 32 few months ago when I replaced a whole bunch of light switches.  Today i made sure both water heaters were on 32's because I thought bigger is better ( I know i'm a dumb ass) and then tested it for ten minutes as stated !!! Simply amazing I am still alive to be honest. It all seems to be ok now although one of the air conditioners would not turn off either with the remote or by pressing the power button on the unit, I had to turn the breaker off to shut it down but that is probably another issue and muddying the waters. So the 32's would be for water heaters and aircons ? I have a shit load of stuff going through that board, my bill averages 8000 baht a month and no that is not a mis type !!

There is a page that is helpful in understanding which size breakers go with which size cables here Simple guide

A single 6000W water heater (6000w/220v = 27A) should be on a dedicated circuit that is on 4mm or greater cable and a C20 or C25 (not commonly used) or C32 breaker. The reason that 4mm cable and a C20A breaker is OK is that they virtually never use the maximum power they are rated for and even if they do the breaker is not going to trip with a 30% overload that will be for a short (20 minutes) period.

 

You will easily be able to confirm which circuits are used by which appliances just by switching off the breaker and seeing what doesn't work. 

Then it's quite easy to see if the wire and breaker is the correct size by adding up all the Wattages of the items that are on that circuit and dividing that by 220  that will give you the Maximum Amps (breaker size) that can be used by that circuit. 

 

If you get very high numbers for a single circuit then you need professional advice.

 

As you are using over 1,800 kWh a month you are probably going to have a high total.

 

Also the bottom left hand C32 breaker looks as if the cable running to it is 2.5mm so the breaker is definitely in the wrong place

 

it also looks as if you have 4 connections to the breaker above that one while you have space on the right. That probably isn't a good idea either.

Edited by sometimewoodworker
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Posted (edited)

I don't think anyone has caught on that the breaker shouldn't be a C32 it should be a B32 and be sure the cable connected is rated for 6 kw =4mm minimum. C breakers are for motors and take a lot more amps to blow . Also the voltage if low will cause higher amps so factor that so may need 10mm cable 

Edited by Stevey

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