DC DIN rail breaker up in smoke and now looking for replacement

[RVLiFe]

Purchased a DC breaker for between my PV array and SCC off Amazon last year. I’ve recently been noticing some intermittent power issues in my history on the Victron VRM site. Today I discovered no power at all coming in from the panels even though it was clear skies. So I open the front compartment of my RV and I could smell something that gave off the odor of melted plastic. This is what I found!

At this time of year, my system only outputs 65 V and 10.2 A. I’ll add more panels as the season gets shorter. The breaker was rated for 250V and 32A but yet it failed. Thank goodness it thermally shut itself off but what could have caused this? I always use quality ferrules on my connections and I had everything tight and solid.
Was it a cheap breaker or too much heat on the ferrules because not enough surface area contact? Any ideas as to prevent this from happening again? I’m seriously considering on cutting all my ends off and stripping the wires back and no longer use ferrules. What are your thoughts on this?

The biggest question and only one that seriously needs to be answered is which brand of mini DC DIN rail breaker do I purchase. I will only ever max this PV system out at 100V and 20.4A so I think a 32A breaker should be sufficient.

 

[Shimmy]

To me that looks like poor torque on the connection. Can you provide a picture of the wire insulation that was connected to it?

 

[RVLiFe]

Are you looking for an insulation rating or just a picture of the after effects? Ferrule and insulation looked slightly discolored from heat as well as the actual metal connection in the breaker but I have a hard time believing it was a loose connection. I just checked my connections a month ago. I will believe you if you insist it was my fault though. I’ve already cut it off and shortened the wire a little to expose good wire again. No ferrule added yet.

 

[RVLiFe]

That particular ferrule didn’t look square. It had slight indent to the sides leaving edges more pronounced. Maybe not enough surface area making contact? This is why I’m thinking of not using ferrules again. You could also see a slight rectangular look to the ferrule telling me it was being squished by the connector.

 

[Bluedog225]

I would be surprised if a quality copper ferrule caused an issue. I can’t see how it would result in less surface are of contact when compared to moderately randomly squishing the wired with a screw.

 

[400bird]

I'd second the poor connection. Maybe it was a poor internal connection that happened in manufacturing. But, the heat discoloration is all around that single connection. With screw/clamp connections connections, I always torque them the first time, then recheck them after the first test run (or a few days after the first torque)

 

[RandyP]

How did you install the ferrule on each wire. Was it crimped to the wire ? Did it result in a round or square/rectangular final assembly ? Or did you put the ferrule over the conductor strands and place it in the set screw breaker term point and then use the set screw to tighten the ferrule down on the wire ? That's why a good picture of the failed ferrule / wire end would be a great thing to post.

 

[400bird]

How did you install the ferrule on each wire. Was it crimped to the wire ? Did it result in a round or square/rectangular final assembly ? Or did you put the ferrule over the conductor strands and place it in the set screw breaker term point and then use the set screw to tighten the ferrule down on the wire ? That's why a good picture of the failed ferrule / wire end would be a great thing to post.

Crimping the ferule is better, but the screw terminal is going to do the real work. As long as the screw is tight the contact to the wire is done.

 

[RVLiFe]

I have a ferrule crimper and it makes nice square connectors with evenly pinched ribbing down the length. I will see if I can find the end I cut off and post it on here.

I could not find how tight to tighten with a torque wrench so I just go hard!

 

[RandyP]

Crimping the ferule is better, but the screw terminal is going to do the real work. As long as the screw is tight the contact to the wire is done.

I guess I don't agree. The ferrule should be properly crimped on the wire first, preferably making a cold weld joint between wire conductors, and then the assembly should be be placed under the set screw terminal of the circuit breaker, and tightened sufficiently to make a good connection. If you can wiggle the wire/ferule combo loose from the breaker term setscrew point, reinsert and tighten more. I saw the loose ferrule on wire conductors method being used in a youtube vanlife video. Did not agree with that ferrule installation method.

 

[RVLiFe]

I found the ferrule that I cut off. Still has a little red insulation on it so it’s absolutely the one I cut off. As you can see, I use a crimper and would never rely on the connector to make a crimp.

One edge has a very pronounced copper color where the tin has been removed.

 

[John Frum]

I've never seen a ferrule make a cold weld.
It may happen but I've not seen it.

 

[RandyP]

I found the ferrule that I cut off. Still has a little red insulation on it so it’s absolutely the one I cut off. As you can see, I use a crimper and would never rely on the connector to make a crimp.

One edge has a very pronounced copper color where the tin has been removed.
...

Ferrule install looks good to me. Those are tinned copper strands, right, and not aluminum strands ?

 

[RVLiFe]

I've never seen a ferrule make a cold weld.
It may happen but I've not seen it.

I believe he just means that no solder was used in the crimping process.

 

[RandyP]

I've never seen a ferrule make a cold weld.
It may happen but I've not seen it.

I kinda' suspect that does not happen either. The ferrule material I have used is too thin to hold up to such a crimp in my opinion. But it would be nice if it could happen.

 

[RVLiFe]

Temporarily, I created a small jumper with MC4 connectors on one end and ferrule on the other end and connected the panel wire directly into the Victron SCC. I’d like to get a replacement breaker as soon as possible but want a quality one this time. Any breaker brand recommendations for 100V 20.4 amp MAX going thru the 10AWG wires.

 

[RVLiFe]

I kinda' suspect that does not happen either. The ferrule material I have used is too thin to hold up to such a crimp in my opinion. But it would be nice if it could happen.

Ferrules I use are thicker than most I’ve seen on Amazon and make extremely solid connections to the wires with very little ability to be squished further.

 

[RVLiFe]

Are these any good? I’ve seen them posted on here before but don’t recall the reviews.

DC Miniature Circuit Breaker, 2 Pole 500V 25 Amp Isolator for Solar PV System, Thermal Magnetic Trip, DIN Rail Mount, Chtaixi DC Disconnect Switch C25 https://a.co/d/46nZs5P

 

[RandyP]

Ferrules I use are thicker than most I’ve seen on Amazon and make extremely solid connections to the wires with very little ability to be squished further.

I had a challenge getting ferrules that would work with the wire I chose to use, and then getting a crimper that would produce a well crimped wire/ferrule.

What ferrules did you choose to use. What crimper worked for you. Just trying to improve my game before the next ferrule install I do.

 

[400bird]

I don't see any indentation/deformation from the screw terminal getting tightened onto the ferule.

I've never seen a ferrule make a cold weld.
It may happen but I've not seen it.

I agree. The standard ferule crimpers have spring loaded jaws. That with the thin wall and low force, there's no way they form a cold weld.

I guess I don't agree.

I didn't mean to say it was the proper method, just that I wouldn't say it was the cause of a connection issue without further testing.

The ferrule should be properly crimped on the wire first, preferably making a cold weld joint between wire conductors, and then the assembly should be be placed under the set screw terminal of the circuit breaker, and tightened sufficiently to make a good connection. If you can wiggle the wire/ferule combo loose from the breaker term setscrew point, reinsert and tighten more.

Yeah, that isn't the fault of the ferule. It is the operator not torquing properly.

I saw the loose ferrule on wire conductors method being used in a youtube vanlife video. Did not agree with that ferrule installation method.

I've got a crimper and would always recommend using a crimper. I hope no one thinks I'm saying the crimp useless. But, it's not going to make an install fail.