DC Circuit Breaker Fires!!

[Honuz]

Is there a way to tell if a breaker is polarity sensitive or not? Some marking or label?

I'm trying to figure out if this breaker is polarity sensitive or not: https://signaturesolar.com/nader-dc-circuit-breaker-60v-200amp/

I bought several 600VDC 20A breakers to act as disconnect switches for my PV arrays and had no idea about the polarity sensitivity until I stumbled upon the one single YouTube video I could find about them. Even the local solar shop that sold them to me didn't mention it.

If there is a line and load described poles .. i would follow them.

 

[JRH]

Stay away from these. They Trip at the right Amperage maybe two or three times and then the internal mechanism starts to go bad. Also someone did a Flir image sensing on them and found one of the contacts gets very hot even during normal operation. He disassembled it and it was really poorly made.

I am simply amazed that in a country that the average new car payment is over 600 per month that we are having a discussion about buying these damn 15 dollar cheap- o Chinese breakers and switches to protect our $ 300,000 home from our $15000 dollar solar system…
What are people thinking…? these things are your only safty line if somthing happens..
I don’t get it…somthing is wrong with our logic….

 

[meetyg]

Just for reference, I found this helpful video, where he describes how to properly wire DC breakers.
Maybe he's not the most professional guy, but he does have a good explanation (you can skip to around 4:15 on the video for the explanation):

 

[OS2/Dude]

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

DC CIRCUIT BREAKER FIRES is a BADLY made video. You do NOT change wire color at the breaker. I assume the intent was to show the breaker has a HOT side and a LOAD side. The video should have labeled the wires HOT & LOAD to show what they were trying to say, NOT change the wire color. I'm sure it will cause a LOT of reverse polarity issues. [The breakers should label each end as HOT / LOAD instead of + / - ]

 

[wpns]

Slight digression: If you have RSD and can just depower the array, do you need disconnects, fuses, and/or breakers on the PV wires?

 

[timselectric]

Slight digression: If you have RSD and can just depower the array, do you need disconnects, fuses, and/or breakers on the PV wires?

Disconnects are for maintenance. Not always required, but always recommended.
OCP (Over Current Protection) is only required when there's more available current than a single solar panel is rated to handle. Usually (but not always) , this threshold is reached when 3 or more strings are put in parallel.

 

[efficientPV]

I tested a 32A PV disconnect that didn't open at 90A. I found some breakers had a better arc interrupt when connected backwards. Put a beraker outside n crappy box with wires entering top is asking for disaster.

 

[再生可能 エネルギー]

Slight digression: If you have RSD and can just depower the array, do you need disconnects, fuses, and/or breakers on the PV wires?

I might be wrong because I never used and tested RSD, but I think that the great advantage of RSD is not that:
- you can not only isolate each PV and shutdown and also turn off the Solar Charge Controlers (since they don't receive any PV input),
- but also turn off the DC/AC Inverters remoteley.

So then you can easily and safely turn off any switch or circuit breakers, on the area you need to work on, since there will be no load current.