It's not much of a test without verifying that it does trip at the rated current.

Testing breaker is normally not like testing a switch... you must test the trip amp too.

red is for danger live green is for safe

(1:00) Thermal circuit breakers are heated/tripped by current (P=I^2*R), system voltage does not have any effect at all on the trip current. The voltage rating of a breaker is do do with arc suppression, if you run a 12V breaker at 48v it may be unable to survive the arc upon disconnecting and blow up.

Have you shut that breaker off under load to see if it will arc over or not? Its a good test to try what happens if it trips ,arcs over and catches on fire ? My worry with most dc breakers is can they quench the arc

Did you test disconnect under fully load ?!! I think it will fireup

Steven have tested the breaker and see how long does it take to trip the breaker say like at 120% of rated current?

⚠️❌‼️ Warning! DC breakers shown (white with blue toggle) are polarized. Look closely and you can see the +&- signs. The polarization at the bottom of the breaker would of course be same as the top(straight through). They have an arc channel. To feed it backwards can cause damage or fire it you are feeding high voltage though it. They have those breakers up to 1000 volts on Amazon. DC high voltage can draw amazing arcs and can kill you. Dangerous as hell. The black rv/marine versions are only good up to 48 (56) volt systems. Use a charging resistor to load the capacitors in an inverter or charger to make them last. Use name brand of the rv type or you risk damage.

My plan was to use it as a double pole disconnect, off, on switch for solar panels, with a Anl fuse, i dont trust the marine dc breakers, unless i pay for the premium brands, im sure some doing the same, I have to test it and see if it works too

I would love to see them switch off with a current around 80A drawing. So we could see if the arc got extinguish fast enough. Also your Cables look kind of small. What mm² is this? How much can the Breaker handle? I want to use 2x25mm² in it.

Any updates 3 years later on these tomzens

Hi Steven, I have also had the same quest; to find a low cost, low voltage, high current DC circuit breaker for my solar system. I have tested the black cased breaker you started with. It looks very nice but, has huge electrical problems. They trip in less than a minute when the marked current is run through it. When applying a long term (at least 10 minutes of operation) current, they trip at 1/3 to 1/2 the marked rating. Also, resetting the breaker changes the trip current a few percent and tapping on the breaker causes it to trip at a reduced current (up to 20% reduction). On the second breaker you reviewed, I think these are a magnetic and thermal type. The 63 amp limitation I think is due to the case width, which limits the size of the internal contacts. I have yet to do any testing on these but, they look a bit more promising since there is an industry spec they are designed to meet. Thanks Steven for doing the informative video.

Thank you, sir.

I bought these on aliexpress. 2x 2P 100A DC600V TOMZN STILL WORKING 2X 2P 125A DC600V TOMZN FAULT AFTER 6 MONTH (1 tripe at 90A) 2X 4P 125A DC1000V EARU 1POLE FAULT AFTER 3 MONTH 1X 2P 150A DC240V TAIXI STILL WORKING max 58.8V 200A test

I have the exact breaker in 2P hooked with my 400ah Lithium battery running easily over 100amps.

This will definitely have someone thinking that if a circuit breaker is capable of carrying that specific amp that it is also capable of tripping on electronic anomaly.

These are for your panel wires going into the charge controller, always fuse your power cable from your battery to the inverter.

Hi, is this circuit breaker enough to protect Lifepo4 batteries or should it be combined with fuses?

I may be wrong, but I think that marine breakers are magnetic, and the solar breakers are thermal. I just had the same issue with a 50A thermal breaker (inline bullet design) falsely tripping at 24A@30Vdc. I just ordered a 50A marine breaker to replace it..... hoping that this will solve the issue. Thanks for the informative video.

Trying to built a 48v system. Can you give me some advise how should I connect my panels and batteries either series or parallel?

How has this breaker been working out for you? Good job on the video.

Also it isn’t recommended to use a fuse holder switch as a switch on a regular basis. Isn’t designed for regular switch use. Use something else for a switch. A disconnect switch that is designed for opening circuits under load. I also prefer not to mount such circuit items to wood. I use metals.

You called that testing? I was expecting the breaker to trip at +/- 125A but none.

Parallell connect 2 breakers double the amp volts remain the same

You need to test if it actually breaks at 120+ A Without catching on fire...

What's the capacity of your Battery pack? are those 18650 cells?

Watts is what heats the internal bimetal strip, but it's I*I/Rstrip, not I*Vsystem

When you say AC is running. Is it s 3-4 ton unit.

Abb s202 its good for battery ?? With 48 v

China makes some high reliability ultra slow blow breakers. Just a wire and a switch inside.

maybe test it actually breaking the circuit?

Your 12V breaker is having contact issues, not because of the current, but because it's a 12V DC breaker! It's about the current *and* voltage in DC breakers, you can't just match the watts using any voltage/current combination. That breaker was rated at 12V because of the arc it will produce when it trips. At 30V the arc is going to be a lot more difficult to terminate. The extra time it takes to extinguish produces more heat on the contacts and has left permanent damage on them. The voltage must be under the rated amount at all times to prevent arcing when it trips.

Are you in the US? I ask because Fahrenheit.

Is it a quality product then?

I have some tomzn products, not all of them work. be careful

Its good? TOMZN ?

what a waste of time... didn't even test over 125A to see if it trips..

No no no... Don't be impressed with those . They are just switches NOT breakers without any safety . Open one of them up and you will see.

That is not a good test

Wait a second. Are all your cabling and components also rated for 120A then??? If not, *you are creating an extremely dangerous situation and fire hazard here!* A breaker/MCB like that is there to protect your cabling and components for over-current, nothing more. It is also not there to protect you/human from electricity or life-threatening currents, that's what RCDs are for, which are completely different than MCBs. So, if your cabling and equipment is also not rated for 125A, then this breaker is useless (well, maybe to protect for just a short circuit, but still... since the MCBs are rated much higher, they might even not break in time, or worse, react at all). So, *you should be using breakers which are rated for the maximum current your system equipment and cabling can handle*, NOTHING MORE! Any higher rated breaker is useless to protect it and in fact dangerous. If you pull more than 63A, you should also upgrade _ALL_ your cabling and equipment so they can handle 125A or more. (note 80A and 100A should also exist and much better suited for your setup as far as I can tell from your video here) A breaker is also not a switch (I got the impression in the video you said you used it to quickly turn off everything?). An MCB should never be used as a switch. It has a limited lifetime and constant switching it off/on yourself will damage the contacts of the unit and shorten it's lifespan and safe working ability considerably. And a note about quality/price/Chinese products: As much as I love Chinese products, electronics, gadgets and stuff, and as much as I buy them all the time, especially from AliExpress, be very careful trusting your home and life with those Chinese MCBs/RCDs products! I have seen quite a lot of catastrophic failures of those on many occasions. Also, you said "from the manufacturer store"...note that those stores on AliExpress are not always the original manufacturer!! On the contrary, quite a lot of those stores are nothing more than resellers who have copied the name of the manufacturer to look genuine, but are not linked to the manufacterer at all. And as long as nobody bothers to check or report, AliExpress does not remove or block those (re)sellers; there are a lot of 'stores' selling counterfet and even pirated and illegal stuff on AliExpress. Secondly, there are also many Chinese manufactures which produce low quality products. Even labelling them with holograms, CE or QC marks, etc. They are not necessarily counterfet per say, but such labels and marks also will not guarantee high quality standards either. The only way to check is of they have an ISO-standard and if those do apply to the sold product (which is extremely difficult to check as a buyer). So, I'd be VERY careful with such stuff, especially if your house, or worse, your life, depends on it!!! *You really get what you pay for in this case!* There is a reason why MCBs/RCDs are not that cheap (well, ok, besides capitalism, but still) If it seems too good to be true, it probably is in this case. Again I can't stress enough how dangerous many of those MCB/RCDs from China often actually are! Note: I can't find any link to that "official store" on AliExpress at all from their official homepage though. They do link to Alibaba from their official homepage. Also no links to their home page from that "official store" on AliExpress. Most real official stores do have links to their home pages and vice versa. Not saying that seller isn't the "official store"... but yeah, some bad indicator flags are raised though.

South african oke using pounds and fahrenheit... you hella confused bra..lol

What you are saying makes no sense at all. Only the current trough the breaker matters: P = I^2 R