Now I gotta go check all my connections just so I'm not worrying about it. Dang it. 🙂 I periodically check everything with the temp gun or just feel the wires when it's ramped up, but it probably wouldn't hurt a thing to put a wrench on everything. Don't burn the place down, Doc!
I was quite surprised with this failure. I do think I will be removing all the ferrules on the THWN wires. Every connection I made was tight, the factory connections not quite tight as mine. I think this failure was on the factory side.
What’s weird was the wire in the IMO looked like it was pretty hot on the line side of the PV, I have never seen a DC arcing problem like a loose connector from thermal cycling affect anything so far upstream.. very nice clean install, so many look like fire traps and this is exactly why putting wiring in metallic raceway is important… thanks for sharing..
Could be increased resistance due to the ferrule. I'l be removing the ferrules in the IMO. Thank you for the kind comment, I like things neat and orderly when it comes to electrical, properly grounded and protected.
We had the discussion on the DIY solar forum and the consensus is that with fine stranded wire use a ferrule. With something like THWN with a set screw type terminal, use a ferrule. With THWN and a clamp type terminals like the IMO has and this MPPT, do not use a ferrule due to the low number of strands. I do believe the low stranded wire will have more surface contact area with the clamp type terminals compared to using a ferrule with low stranded wire, thus less resistance and less heating effect.
Amperage is about 13A at full peak PV power, the wire is 10 AWG THWN with 105°C insulation from array. I showed the wire inside the charge controller, that was 14 AWG with 105°C insulation. Even 14 AWG would be sufficient for the current of 13A. The failure is due to resistance of the connection, my thoughts are either the factory assembled connection wasn't tight enough, the plastic for the connector cracked or the connections loosened over time due to heating cycles.
I've seen spade connections internally on the LV6548 PV terminals and have seen the same on the 6500EX.These are only carrying 12 to 13A at peak PV power, I've seen blower motors run for 30 years with 30A running thru a spade connector.
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Update to this video th-cam.com/video/3JkTFK4jJkk/w-d-xo.html
Very clean set up, in spite of the char marks. Thanks for sharing.
Came here to learn about the “Magic Smoke” and ended up learning about your IMO. Thanks for the video, Doc Zwy!
Thanks for sharing. I'm glad you didn't experience any damage to your home as a result of this as things could've gotten a lot worse.
Now I gotta go check all my connections just so I'm not worrying about it. Dang it. 🙂
I periodically check everything with the temp gun or just feel the wires when it's ramped up, but it probably wouldn't hurt a thing to put a wrench on everything.
Don't burn the place down, Doc!
I was quite surprised with this failure. I do think I will be removing all the ferrules on the THWN wires. Every connection I made was tight, the factory connections not quite tight as mine. I think this failure was on the factory side.
What’s weird was the wire in the IMO looked like it was pretty hot on the line side of the PV, I have never seen a DC arcing problem like a loose connector from thermal cycling affect anything so far upstream.. very nice clean install, so many look like fire traps and this is exactly why putting wiring in metallic raceway is important… thanks for sharing..
Could be increased resistance due to the ferrule. I'l be removing the ferrules in the IMO. Thank you for the kind comment, I like things neat and orderly when it comes to electrical, properly grounded and protected.
Definitely use ferrules
We had the discussion on the DIY solar forum and the consensus is that with fine stranded wire use a ferrule. With something like THWN with a set screw type terminal, use a ferrule. With THWN and a clamp type terminals like the IMO has and this MPPT, do not use a ferrule due to the low number of strands. I do believe the low stranded wire will have more surface contact area with the clamp type terminals compared to using a ferrule with low stranded wire, thus less resistance and less heating effect.
The wires look like they are to small for your current. How far are you running? Before and after the switch.
Amperage is about 13A at full peak PV power, the wire is 10 AWG THWN with 105°C insulation from array. I showed the wire inside the charge controller, that was 14 AWG with 105°C insulation. Even 14 AWG would be sufficient for the current of 13A. The failure is due to resistance of the connection, my thoughts are either the factory assembled connection wasn't tight enough, the plastic for the connector cracked or the connections loosened over time due to heating cycles.
Why are they using a poxy spade connector at the motherboard side, those connections are useless !!!
I've seen spade connections internally on the LV6548 PV terminals and have seen the same on the 6500EX.These are only carrying 12 to 13A at peak PV power, I've seen blower motors run for 30 years with 30A running thru a spade connector.
Ferrules are best
loose contact
If it was loose, it would have been on the factory side.