Fire sign on 12A breaker

[SolarMusher]

Hi,
When changing my 4 years old PV combiner for an upgrade to a 300VDC combiner, after I removed the breakers block, I've seen sign of fire at the back of one 12A breaker (Solarworld 175W mono). This system was 48VPV/48VBatt with an MX60. I hadn't noted a lower Watts output before the upgrade. Everything was working fine. I wonder what could be the origin for this sign of fire (the combiner has also the same mark).
Thanks for your help,
Erik

[mike90045]

fire sign ?    you mean a stamped logo or soot and char marks ??

[SolarMusher]

Hi Mike,
I mean char mark on the Din Rail in the combiner, behind the breakers block and one breaker which has soot mark on its back (at the same place), but I have checked all my PV series and all seems to be fine.
Erik

[boB]

Whew !   I thought you meant   Firesign Theatre !!

(www.firesigntheatre.com)

[SolarMusher]

Very helpful...
Thank boB
Erik

[Halfcrazy]

Erik
Any pictures? I can only assume it was arcing through to the din rail? I wonder if Ground Fault protection would have caught this? Or Arc Fault Protection. Maybe it was not arcing to the din rail but arcing internally?

Ryan

[SolarMusher]

Hi Ryan,
I didn't have GFP installed on this old installation, because I wanted to upgrade to 72VDC with a Classic for summer. I think this breaker had to arc internally. But why only this one? It was on a Solarworld string of two 175W mono.
Two years ago, my whisper 200 was hit by a direct strike in the night, may be it could be one the reasons.
I would like to understand what was happened and if I made a mistake where I made it. Now that I know this could happen, I will check my combiner more often even if I think that my system is more secure with a Classic . This combiner is located on a log wall and I don't want this lodge to burn . I'll send you a picture.
Thanks Ryan,
Erik

[Halfcrazy]

I bet there is a connection between the lightning strike and this? It would appear from the description that there was an arc out to the din rail. I also suspect it was not continuous or the breaker would have eventually melted down.

Ryan

[niel]

me thinks one of these may be in order.
http://www.solar-electric.com/suprde.html

[Robin]

Good idea on the SPD. I wonder if moisture can be getting into the combiner and onto the breaker? It is normal to have some condensation in the combiner in the morning, but I have never heard of arcing? Lightning may have caused it, but at this point there is no way to tell. Make sure the combiner doesn't have holes in the top where the bends happen. If you can see air through the top, add silicone in the corners.