Tomzn DC Circuit Breakers (Yellow vs Blue)

Just learning here...Anyone shed some light on any of the differences between these two aside from the voltage rating or is that it?

Yellow= 600V

Blue= 440V

My follow up question is when comparing to brands like MidNite Solar (150V) and Eaton 48V single pole / 96v 2 pole, can one really trust the voltage ratings of the Tomzn? My application is low voltage but I was curious because it feels more like a AC rating, but its a DC breaker.

EATON

Another observation is the Eaton when wired in series increases the voltage. The Tomzn has clearly marked +/- symbols, was this intended for fusing both sides of the source, or to be wired in series to increase rated voltage?

I ordered a handful of different beakers from AliExpress... my intention was to test on video various fault conditions. Looking to test this the right away, and to learn in the process.

Any tips would be appreciated.

I use Tomzn breakers on my system. They seem to be better quality than the typical cheap Chinese things. I have the yellow PV-rated on the PV side of my charge controllers and use the heavy duty 80A blue version on the battery side of the charge controller. They work fantastic for disconnects, but truth be told, I have never tried testing the over-current scenarios, nor do I know what the difference is other than the voltage ratings.

Both the blue/yellow Tomzn are polarity specific. The Eaton breaker is UL-listed and there are new NEC requirements with DC breakers that require them to be non-polarity specific - which is why that one isn't marked +/-.

Sorry I don't have an actual answer to the "what are the differences" question, but if price is not a concern, always go the UL-listed route whenever possible

I had a bit of an oversight on the intended application of the yellow/PV because I bought those for use with my batteries. I wonder if they would still be suitable for use with battery.

I have about 10 breakers on the way, but both 2 pole options are yellow.

Do you have any 2 pole tomzen breakers and how have you wired them?

CrimpDaddy said:

I had a bit of an oversight on the intended application of the yellow/PV because I bought those for use with my batteries. I wonder if they would still be suitable for use with battery.

I have about 10 breakers on the way, but both 2 pole options are yellow.

Do you have any 2 pole tomzen breakers and how have you wired them?

Click to expand...

I use the two-pole yellow on my combiner box. Power flows in the top and out the bottom. They are not bi-directional.




I use the two-pole blue between each charge controller and the battery bank. Power flows in the top and out the bottom. They are not bi-directional either.




This was my understanding of how to wire them after asking around a few times. Neither breaker can be used anywhere where current could flow both ways.

I replaced my TOMZN breakers with Schurter ones. I don't trust them and they are aren't listed in the US.

There's also the Noarc brand which are non-polarised

where is it possible to buy the NOARC Breakers?
prefered in EU

Hello Out There

Max Voltage : Refers to the gap of the contacts will break the arc of current flow , DC current has a larger arc than AC

I would want the Bi directional ones because a short can happen on either side of the breaker , Because of the storage
batteries and source of charging . AC only on capacitor circuits mostly.

Jim Jr

In EU get Schneider. They cost nothing and approved all EU kind of

mike said:

CrimpDaddy said:

I had a bit of an oversight on the intended application of the yellow/PV because I bought those for use with my batteries. I wonder if they would still be suitable for use with battery.

I have about 10 breakers on the way, but both 2 pole options are yellow.

Do you have any 2 pole tomzen breakers and how have you wired them?

Click to expand...

I use the two-pole yellow on my combiner box. Power flows in the top and out the bottom. They are not bi-directional.




I use the two-pole blue between each charge controller and the battery bank. Power flows in the top and out the bottom. They are not bi-directional either.




This was my understanding of how to wire them after asking around a few times. Neither breaker can be used anywhere where current could flow both ways.

Click to expand...

I appreciate you taking the time to reply. I understand the direction of flow as you outlined, but please allow me to elaborate what I was trying to convey.

I have noticed some breakers wired in series... usually on two pole+ breakers. EATON and MIDNITE both have different voltage ratings depending on how its wired. EATON for example is 48v, or 96v when in series. Here are some visual examples.





I was curious of the Tomzn rating of 600VDC was when tired in series...it appears both of these would be valid ways of connecting it.




I also recently picked up an ABB Shunt Trip to use as my primary battery service breaker, mainly for the shunt trip function, but also noticed now they recommend to wire a 2 pole and 3 pole DC setup.










Either way... looking to have some fun and test these out.

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JimJr. said:

Hello Out There

Max Voltage : Refers to the gap of the contacts will break the arc of current flow , DC current has a larger arc than AC

I would want the Bi directional ones because a short can happen on either side of the breaker , Because of the storage
batteries and source of charging . AC only on capacitor circuits mostly.

Jim Jr

Click to expand...

Yes, I agree that bi-direction would be ideal, especiallyfor certain conditions where flow could be reversed, like when charging.

Because I have directional breakers, my charger would have its own breakers flowing in the right direction. As my system gets closer to production levels, I will be upgrading components to UL listed brands, primarily EATON or Schneider.

As of right now, I am still just experimenting,testing. and designingfor my own entertainment.

CrimpDaddy said:

Yes, I agree that bi-direction would be ideal, especiallyfor certain conditions where flow could be reversed, like when charging.

Click to expand...

FYI, as the breaker trips, polarity specific breakers expect the electric arc to "flow" in just one direction, and the mechanism to interrupt/extinguish the arc is designed to handle just that direction. Install that breaker the wrong way in a sufficiently high voltage/amps system, and the arc will keep going indefinitely, likely resulting in a fire. See the YouTube video for a very dramatic demonstration.

Polarised Solar DC Circuit Breakers - Reverse Polarity

Excellent video. At this stage I feel I have a good understanding of polarity and why it matters. I can certainly see the value in a bi-directional DC breaker.

What I still want clarification about is the comments in my last post about wiring a breaker in series. Even the breaker in the video you posted was wired in series, which would be a positive branch breaker only. It conflicts with how mike has wired his, even though that also appears correct with the load wired across the two bottom posts. While its right, it might cut the DC rating in half.

Even my ABB shunt trip has instructions to wire DC in this manner.

Personally I feel the 600VDC rating on the Tomzn only applies when wired in series, which is what I set out to try and confirm.

You wire it in series over like that to have a wider gap and tollerate higher voltages. Or atleast thats the most common. Like a breaker do 400VDC 1 turn and 600VDC 2 turns.

CrimpDaddy said:

I have noticed some breakers wired in series... usually on two pole+ breakers. EATON and MIDNITE both have different voltage ratings depending on how its wired. EATON for example is 48v, or 96v when in series. Here are some visual examples.

I was curious of the Tomzn rating of 600VDC was when tired in series...it appears both of these would be valid ways of connecting it.

Click to expand...

Provided you use double-throw breakers (ie. Left pole part and Right pole part are physically synced) and in the same electrical circuit, either wiring has the same double-strengthelectricity/arc cutting effect. It's just changing the order of the parts - it makes no difference to the electrons.

PatternA (right pic): [PV+] -> [BreakerLeftPole] -> [SolarCharger] -> [BreakerRightPole] -> [PV-]
PatternB (left pic): [PV+] ->[BreakerLeftPole] -> [BreakerRightPole] ->[SolarCharger] ->[PV-]

So in both PatternA and PatternB, BreakerLeftPole and BreakerRightPole are wired in series, just in a different order.
I think most people prefer PatternA, as this physically disconnects from both PV- and PV+, and would probably be safer should the panels have some sort of grounding fault.

I have Tomzn breakers from 3A to 125A in 1 pole to 4 pole configurations.. my conclusion so far... use the lower rated units only (upto 63A).

I have tried tripping a single pole 100A unit by plating around burning 10mm2 cable with way over 300A spikes and even once had a slight accident of a short for a second (enough to heat up a 10mm2 cable to melt the inner plastic) and the 100A breaker did not trip... that was concerning.

For higher amps use a 4 pode device (4 x 20A) to get an 80A breaker for example, rather than going for a single pole device at high amps.

Don't run them near 100% (of any breaker for that matter) as the heating effect will have a more significant effect on contact resistance (heating and cooling cycling loosening the joints) and will end up heating up more and burning out.

I have posted some images on a previous thread where I stripped some down as they do have an issue in that when they are tripped after a serious fault the contect surfaces seem to be affected quite a bit (relatively) and the units would then trip if your using them at high loading levels.

I have had some AC rated devices arc on about 160V DC continuously until they burn out, fortunetely they don't seem to set fire or at least the 4 that I have had burn out in various ways have not shown significant enought heat damage to show any flame.... that said don't mount them on a wooden board or at least have a good air gap behind them..

Random rants done.

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The DC units may have larger contact separation in addition to the tiny magnet that is installed to deflect the polarised arc..

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Lat one.... with polarised breakers and battery packs you tend to end up with a breaker at each end of the wire... to cope with fault origins at either end.

Sometimes I get impressed with how fast stuff from China actually gets here... I ordered a small assortment of breakers to play with.

LithiumSolar said:

I use the two-pole yellow on my combiner box. Power flows in the top and out the bottom. They are not bi-directional.

View attachment 13880


I use the two-pole blue between each charge controller and the battery bank. Power flows in the top and out the bottom. They are not bi-directional either.

View attachment 18565


This was my understanding of how to wire them after asking around a few times. Neither breaker can be used anywhere where current could flow both ways.

Click to expand...

I know this is an old post. I just wanna ask you if this circuit breaker's input can go from top or bottom, or just from top?
Some people says it's ok to have input from bottom.
THanks.

I would only go from Top, as if you look at the front of the breaker there are diode indicators on the breaker side, the part of the image going down (#2 on the pinout). These usually denote the wiring flow direction. I suppose if you need the wiring to go the other way, you could always flip them over so they are up-side-down instead(?)

awan2008 said:

I know this is an old post. I just wanna ask you if this circuit breaker's input can go from top or bottom, or just from top?
Some people says it's ok to have input from bottom.
THanks.

Click to expand...

Are you guys sure a breaker is one-directional? I never cared about that at an AC nor DC breaker. After all, they are just simple mechanical devices, with a bi-metal trigger. The trigger will heat up same regardless of direction of current flow. Its all about Amps. Voltage rating is all important about breaking the arc with DC. Dump any DC breaker which is light as a piece of paper as they lack thermal mass to help extinguishing the internal arc (there are several chinese brands which lack any mass. For example CS brand). Tomzn are definitly the best chinese ones. If you go for DIN rail, can look for ABB or Siemens too. Price will be 3 - 5x higher tho...

For one, an AC breaker doesn't make much of a difference. The disconnect arc well self quench due to the alternating current
With DC, this is not the case. These breakers can be designed directional. Some of the circuitry in them may be directional. If there is a +/- (meaning Line/Load) or a diode symbol (denoting direction of flow) you need to wire them in that direction. Otherwise, it is possible the breaker will not trigger when it is supposed to (either too late, or too early)

With DC breakers, some of them have a current sense coil. If the coil is energized in the wrong direction, then it will not trigger the overcurrent protection and in fact keep it from working at all.

Not all DC breakers use a bi-metallic current trip strip. This is because DC creates a nasty current arc during heavy load disconnect and the contact pads need to be moved away from each other by distance and speed to quench the arc.

Another term these are called are "Polarized" breakers.