One Circuit Breaker To Rule Them All!

This is my new favorite circuit breaker for battery banks! See why I think it's such a good value in this video. I'm using it with my off grid solar system between my 48VDC Battery Bank, and my inverters.

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Disclaimer:
My videos are in no way intended to be instructional "how-to" lessons. I am simply documenting my project for informational purposes. Property damage, personal injury, or death may result, even when following manufacturer's instructions. I cannot be held liable for such damage or injury. It is YOUR OBLIGATION to ensure that you are complying with any local and federal laws as well as code and permit requirements.

David Poz, LLC

[Suicid]

As an German electrician, no news for me. The trip curves are standardized, for a faster trip time, in household circuits, trip curve b is used, c is only used for circuits with quite long lasting inrush currents, like heavy motors or such. To trip instantly, on B curve breakers you need to have 5 times the rated current, for c breakers it's 8 times the rated current.
So no wonder that it took so long till it tripped. And because of that you normally don't overrate the breakers, rather underrate them.
In your example: 5kw inverter @48V is around 104A, so you would use a 100A Breaker.

[robertmyers]

Thank you for your lessons taught on this subject! I am not an electrician, but I have gone Vocational school over 42 years ago. I am now 61 years old and I am learning a lot about setting up my on solar panel control station thanks to you and other bright men like yourself on YouTube! I am so very grateful to you and others like yourself!😎

[uhayat]

Fantastic!. Your effort to test this in a real use scenario is highly appreciated. Keep up the good work David!

[tripper]

Welcome to the DIN rail world. Outside of the USA, DIN rail MCB's have been standard for mains power in many countries.

[edc]

There is a reason that ABB one is so large, it can reliably break huge fault currents.

[AndyFletcherX]

I've been using TOMZN TOB1Z breakers for a few years. 125A ones are rated at 250VDC and 10KA breaking current - more than adequate for 48V systems assuming the battery series resistance and wiring is less than 5 milliohms (you would have to be using some huge batteries and busbars to be below this). I would be cautious putting contacts in parallel as an imbalance could lead to annoyance tripping.
One thing to watch out for with inverters is inrush current. My Victron 5KVA inverter has >40, 000uF on the input and the inrush is brutal on breaker/switch contacts - use a resistor (500ohm/5W) across the contacts of the isolator/breaker to charge up the capacitors before closing it. Less damage to everything and less stress on the inverter.

[MrRsalaza]

Thank you David this gives me a good idea on how to create a shut off switch for the batteries on my 12000 watt 48V grow watt inverter.

[sergeyblinov]

Concerning DIN-rail MCB's from well European-known brands, like Schneider, ABB, Legrand, Siemens, Moeller (under Eaton brand). General industrial MCB's ("AC version") from these brands have 80 V DC per pole rating. And these MCB's are successfully used in 48 V DC telecom power systems.
Also, the more economical and efficient way (less voltage drop across protection unit), is to use European-style "Fuse-disconnectors". These devices acts as fuseholders and disconnectors for inverter Idle currennts).

[LithiumSolar]

Very cool!! I've been eyeing these for a little while now but haven't pulled the trigger on buying yet. They look very similar (identical?) to my 80A TOMZN breakers. One thing that made me hesitant is that, interestingly enough, there are no UL markings on it despite it having the rating. Additionally UL1077 is "supplementary protector" not "circuit breaker" and am guessing that's probably why. I'm certainly not an expert here, just something I noticed last time I was looking. It was cool to see it breaking such a heavy load though!

[bentleyjarrard]

Great video, looks like a nice, compact easy to use breaker. Based on the negative comments regarding the delayed trip function, its worth mentioning that many DC breakers are available in 3 versions, short, med and long delay. It seems that the particular model you tested was of the long delay variety. If different versions of that breaker are available a follow up video comparing trip times would be excellent. Speaking of breakers, I wanted to let you know I just posted a video with a 175A Midnight Solar Remote Trip breaker and PCB controller. The idea being to eliminate the golf cart style relay that has a large, wasteful stand-by current with the RT breaker and controller PCB which is connected to the BMS relay. I also posted a video with a latching contactor and control PCB that could be used to eliminate the always-on contactor.

[retrozmachine]

@davidpoz try testing the MCB for contact stability. Pass a stable current through the MCB and measure the voltage drop across the MCB using a multimeter while wiggling the lever. Also try testing the voltage drop with open / close cycles of the contacts. To be nice don't hot switch the contacts, ie under load, as this will degrade them. I've noticed that a lot of these high amp MCBs have quite poor contact stability with contact voltage drop varying from 10 to 80mV.

[saleenmustangs]

I just installed a system and used a 150 amp MCB, they are nice!

[TheOnestoppctech]

I rather have it trip sooner. Thanks for the video!👍

[WiSeNhEiMeR-]

HOWdy D-P,
thanks for this TEST
COOP
...

[diode]

I wouldn't use these for this application. A 10kA interrupt rating is too low for the amount of battery bank you have. It would take some calculations to figure out the available fault current and then you would design your circuit protection based on that. At the battery bank I would use a UL 489 fusible disconnect that is load break capable with the appropriate SCCR and you could use a supplementary UL1077 after that if you can find one with the right SCCR. Likely your only option with a high enough SCCR would be another 489 fusible disconnect with appropriate fuses. Since DC never crosses zero, an arc fault event is particularly hard to clear, and without a high enough SCCR it may not clear at all. I don't mean to be a Debbie downer but there is a lot more that goes into circuit protection than matching the amp ratings of the conductors. If you do find a UL1077 breaker with a high enough SCCR you should probably select one that has a B trip curve.

[offgridmgtowhomestead]

I have been using the single pole versions of these for couple years now. Been very, very impressed

[stelaboys]

also 1 thing to note is in my victron setup if using dual or tripple setup you must not trip the ground on the DC side as all the units must stay connected via ground, no idea if its the same for your setup but expect its quite common.

[SkypowerwithKarl]

Please note on the breaker shown, the safety certificate is “CCC” (China) not CE (European) or UL (American certification company). Does that mean it’s any less safe, I leave that to you. I’ve purchased the same brand shown but in AC and 63 amps. I found it impossible to have it safely clamp on stranded THHN wire and pass the jiggle test without it coming out. The only success was stripping twice the normal length of insulation and fold the wire in half before insertion into the terminal. I had to also tighten the crap out of the terminal screws. This concerned me so I junked the breakers and went with Square D for the AC side. I found some rail mount breakers on Amazon for my PV system that’s rated at 1000 volts and carries the “CE” rating(legit??). Those also didn’t pass the jiggle test without folding. I did elect to use those. As for those boxes, notice the mounting rail has two screws. Those screws are small and short. When you mount multiple breakers with large wires you can put a lot of stress on those screws to the point of failure. Try to form the wires shape before mounting the breakers. I drilled the holes out and bolted through with a fender washer on the outside. I also added spacer blocks for additional mounts/bolt through when you have a long rail.

[excillisbank]

Bien, je recherchais ce test à plus de 125A, super merci David.

[billgalloway]

Good info David, thanks. I'm getting ready to build basically the same system as you. The growatt manual calls for dual 150 amp breaker/fuse protection at DC in. In my search I considered that 125 amp breaker but didn't like the over current trip curve, I really wanted to find Din mount 150 amp 10sec trip breakers. To be safe I think what I'm going to do is set up DC busbars and attach 150 amp ANL fuses running to inverter, those ANL's are huge, about 5 inches long, they atach with ring terminal.