DC Circuit Breaker Fires!!

[Rbertalotto]

I recently installed a new MPPT solar controller in my RV. While I was researching new SCC I stumbled upon a couple web sites talking about the proper way to switch solar panels on and off using a DC circuit breaker. So I ordered this one from AMAZON:

https://www.amazon.com/gp/product/B096315TSJ/ref=ppx_yo_dt_b_asin_title_o07_s01?ie=UTF8&th=1

DC Miniature Circuit Breaker, 2 Pole 1000V 63 Amp Isolator for Solar PV System, Thermal Magnetic Trip, DIN Rail Mount, Chtaixi DC Disconnect Switch C63"​

I'm seeing where some DC circuit breakers have the leads switched on bottom and top....+ on the left on top and + on the right on bottom, and opposite for -.

This circuit breaker only calls out +/- on one end......There are no markings on the other end.

If you look at the attached link, there is some type of schematic on the front calling out 1,2,3,4....I'm not sure what this means.

I have it connected + to + and - to - running straight through the breaker..... Is this correct or am I going to burn my RV to the ground?

Three 140w / 12V panels in parallel.....with 4g wire of 25' to SCC

 

[Rbertalotto]

BTW, this is the youtube video that got me concerned....

 

[Texas-Mark]

I have it connected + to + and - to - running straight through the breaker..... Is this correct or am I going to burn my RV to the ground?

Yes. Correct.

 

[Rbertalotto]

Thank you! As you can see in the above video, he has his breaker connected that way and it set on fire! So this was my concern.

 

[rmaddy]

Which positive wire is connected to the + terminal on the top of the breaker? The wire from the panels or the wire from the SCC?

 

[Rbertalotto]

Wire from the panels.......Goes into the breaker marked +/-

 

[GLC]

I just used these on mine. Just need to break one connection.

Amazon.com

 

[rmaddy]

I just used these on mine. Just need to break one connection.

Amazon.com

While that is a high quality breaker it is only good to 48V. What is the total Voc of your panels? Panels in series can easily get much higher than 48V.

 

[Rbertalotto]

GLC....This fellow says NEVER use that type of disconnect. He is quite adamant about it......I was using those CHINA breakers in a few other projects and I found about 70% either did not trip or tripped all the time......I stopped using them and only use ANL fuses now for protection in single wire architecture. But my understanding is that solar panels need both + and - protected per NEC Code....

Go to 5:16 minutes on the video for his reasons

 

[GLC]

While that is a high quality breaker it is only good to 48V. What is the total Voc of your panels? Panels in series can easily get much higher than 48V.

Hmmm, good catch. I am actually at 74 volts and 16 amps.

 

[GLC]

GLC....This fellow says NEVER use that type of disconnect. He is quite adamant about it......I was using those CHINA breakers in a few other projects and I found about 70% either did not trip or tripped all the time......I stopped using them and only use ANL fuses now for protection in single wire architecture. But my understanding is that solar panels need both + and - protected per NEC Code....

Go to 5:16 minutes on the video for his reasons

If you check Will's solar builds, these are the breakers he used.

 

[Rbertalotto]

If you check Will's solar builds, these are the breakers he used.

Is it possible Will is missing something here?

 

[rmaddy]

GLC....This fellow says NEVER use that type of disconnect. He is quite adamant about it......I was using those CHINA breakers in a few other projects and I found about 70% either did not trip or tripped all the time.

I'm confused by this reply. The breaker posted by @GLC is not a cheap Chinese breaker. Bussman is high quality and recommended. Perhaps not for the PV disconnect, but certainly for other parts of your system.

@Rbertalotto the breaker you linked to is a cheap Chinese breaker I wouldn't go anywhere near.

 

[Short_Shot]

Not gonna lie, in about a decade of messing with controls I have never seen a breaker flip the + and - from one end to the other. The reason being they are a sort of almost modular design and each side is usually isolated from one another, aside from a common trip mechanism.

 

[Short_Shot]

Also I bought literally this same breaker.

I have yet to actually test its trip limit, but I have a fuse on that circuit anyways and am using it solely as a disconnect.

 

[Rbertalotto]

and am using it solely as a disconnect.

I believe that is what the fellow in the video I posted is saying. Just use it for a disconnect. The panels should be fused at the panels end of the wire.

 

[Rbertalotto]

Another comment on the Bussman fuse used for solar panel applications:

"
Question:
I thought code requirements require both the positive and negative be disconnected at the same time for solar panels. will my insurance cover this?
Answer:
For Solar you need to have both disconnected as Power wire cares current to the device and the natural line cares a current back at a lesser amount, but can still hurt someone. That is why they have a ground wire that takes it back to ground.
That is my understanding of it.
By Benjean Moses on August 31, 2021
This device is engineered for automotive usage only. It is not intended to be used for photovoltaic systems.
By Lee Allen on August 31, 2021"

 

[Rbertalotto]

The breaker posted by @GLC is not a cheap Chinese breaker. Bussman is high quality and recommended. Perhaps not for the PV disconnect, but certainly for other parts of your system.

Agreed, Bussman is a high quality product.

I used the CHINA breaker I did because it isn't protecting anything. It is simply a disconnect in my system.....

 

[GLC]

My panels are fused and use this breaker as a disconnect. I believe that code is for high voltage solar feed not low voltage feed. I would not use this breaker on a high voltage feed. Currently there is no code in Texas as far as low voltage disconnect breakers.
Just FYI, I also answer questions on Amazon, it does not make me an expert.

 

[Kdkool]

Not gonna lie, in about a decade of messing with controls I have never seen a breaker flip the + and - from one end to the other. The reason being they are a sort of almost modular design and each side is usually isolated from one another, aside from a common trip mechanism.

Probably why they failed catastrophically at those potential. The flipping of the terminals means that the traces are crossed internally and if the two traces are close enough to one another at the crossing, poof!