Small fire this morning, very lucky

Oh my, those blue AC Breakers... the ones the major italian electric company used in my energy meter (without CE marking, can't mount them in Italy!), it broke after one year usage.

DC-breaker-fuses.jpeg
DC Breaker and 10x38 fuses. I got myself some gG fuses, they contain sortof sand inside which helps suppress arc quicker.

fuses-iec-269.jpg
 
Oleksii said:
ohh, I have same TOMZN breakers, DC-C63 ones and only now I've spot that they have polarity signs.
I did not mount them yet!

Is this strongly required to follow polarity for these TOMZN breakers the same way as @ajw22 shared on a YT video for other brand DC breakers?
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Yes, for DC I'd always follow polarity. I had a video on YouTube showing the bad effects of reversed polarity but I can't find it, sorry!
 
One more video for the topic
View: https://www.youtube.com/watch?v=Cup5fMGaE2g

An a nice explanation in comments section:
> If the current flow is in the wrong direction the magnets don't pull the arc into the arc suppression chamber, they deflect it into the body of the breaker.

Related videos:
View: https://www.youtube.com/watch?v=OdiB4GuuSJ8

View: https://www.youtube.com/watch?v=QYSxl-2vLfQ


Based on that, I wonder, are construction of 2 poles DC breakers is different?
I assume that magnets in each pole should be installed in reverse orientation? That's what would make polarity difference, IMO.
What do you think?

I've tried to search disassembly videos for 2 poles DC breakers, but could not find.
 
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It's possible that a double pole breaker may have 1 magnet inside with North/South facing into each space and centered between them. This could allow the arc to be pulled towards the suppression chamber of each breaker of it's respective polarity. Add a little iron plate (which is cheaper than the magnet) and the fields can be extended and strengthened to force even further into the chamber.
Guessing here, of course.
 
Now explain me this. Our batteries work in both directions. So the arc travels forwards and backwards I assume? Do you have to use two breakers in opposites so they're covering them bi-directionally?
 
not2bme said:
Now explain me this. Our batteries work in both directions. So the arc travels forwards and backwards I assume? Do you have to use two breakers in opposites so they're covering them bi-directionally?
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In short, yeah. As long as the breaker is polarized, then you'd need two of them, one for each leg. There are some prebuilt battery packs that have two breakers on the box.

There are those that are bi-directional as well. They are little more, but may be worth it.

I'm not sure, but guessing, the bipolar breakers probably have two magnets inside that push the arc to the extinguishing wick.
 
paddy72 said:
That's really very cheap for a 125 V DC, 63 A breaker! I am not sure if i would trust this chinese crap. Maybe they are good for a one time use ;-)
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one time use is enough, just to prevent your house is burning down......that one time spark....kill it
 
paddy72 said:
That's really very cheap for a 125 V DC, 63 A breaker! I am not sure if i would trust this chinese crap. Maybe they are good for a one time use ;-)
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I wouldn't consider these "crap", really. But definitely "cheap", of course. And as 100kwh-hunter states, as long as it pops to keep from starting a fire, that's all that matters. Even if it pops sooner than rated. And it's really easy to test if it will pop even at the rated current ("rated" doesn't mean it will pop at that amperage, but that it will sustain that current for a period of time, usually 20 minutes, before disconnecting)

BigCliveDotCom did a tear down of these TOMZN breakers:

View: https://youtu.be/w0ntxqTEqyM
 
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Korishan said:
I wouldn't consider these "crap", really. But definitely "cheap", of course. And as 100kwh-hunter states, as long as it pops to keep from starting a fire, that's all that matters. Even if it pops sooner than rated. And it's really easy to test if it will pop even at the rated current ("rated" doesn't mean it will pop at that amperage, but that it will sustain that current for a period of time, usually 20 minutes, before disconnecting)

BigCliveDotCom did a tear down of these TOMZN breakers:

View: https://youtu.be/w0ntxqTEqyM
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Oh very interesting video. I've been using Tomzn breakers, both AC and DC from I think at least 3 years now, never had a problem. Chose this make (and also bought quite a few Earu MCBs from China) over other makes because:
- It has a true CE marking required by law here in Italy;
- They state their products are made respecting different standards (IEC and GB);
- They also publish the standard certifications on their website (and on Aliexpress).

I did have problems with other chinese makes like Chyt (no CE marking). And yes, I'd love to buy myself some other good MCB like Siemens but 30€/pcs is reaaaally expensive!
 
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Thanks for the interesting autopsy video, @Korishan ! I didn't say they dont work, but i really have some bad experience with cheap electronics coming from china. I bought a lot of bigger Mosfets, voltage regulators, diodes, transistors and many of them were crap, not meeting their specs from the datasheet. There are also things form china that work and still for cheap, but if it gets very cheap i would be suspicous. I would have loved to see a real test of these DC-Circuit breakers and how they perform under real life conditions. 125A - DC arcs of 125 V is really a lot of power - you definetly want to make sure breakers work as expected. But its definetly better to have at least any circuit breaker than nothing ;-)
 
paddy72 said:
I would have loved to see a real test of these DC-Circuit breakers and how they perform under real life conditions.
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Yeah, I did a quick search for those videos and most of them were Asian reviews and I didn't understand a lick of what they were saying, plus the quality of the review was super DIY, meaning they just shorted out two bare wires connected through the breaker to a 12V battery :p Not very scientific, imho. But, at least they popped under 100+ Amps @ 13VDC, so that's good!
 
Test DC circuit breakers
here is something i found in my search. Not really what i wanted, but it shows what happens if you connect a (good) DC-circuit breaker in the wrong way (polarity) - it catches on fire! Would still be interesting to see the insides in action and what happens on over voltage and how often it will perform correctly.
 
My original esmart3 mppt controller also died because of a loose connection. I'm not sure if I posted it in my build when it happened but the connection from the cable to the circuit board wasn't tightened properly by the mfg. It melted the cable and caused my output to drop to the point that I noticed it. If I had not noticed this, I would have assumed that it would have heated up and melted more things and caught on fire. This seems to be common when you have high current applications where your wires do get warm. The expansion and contraction from the heat will loosen up the screws. I now periodically go in and tighten all my connections. I need to inspect it with my flir when the solar is at its peak.
 
After reading this and watch some more YT.
I got rid of the switches that i thought they where protecting.....
They where NOT bi directional. now is not so much of a problem, but in the summer....with full load and full discharge...
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I toke them out...better safe save than sorry...ignition protected....my a**s........one way.... yes
It is really worth the trouble to do some research on this subject. you would be surprised...
I put in per batt bank a 300a 80v cell becouse they where the fastest, in 4 weeks i will get the 100A 80v.
The 300a will move closer to the inverter.
Its not ac but dc we are playing with....one way traffic or load and unload...
Be save
 
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