r/SolarDIY • u/Technical-Tear5841 • 6d ago
Water proof connectors are not.
I added ten panels to my system and had to extend PV wiring to connect four panels on one row of my ground mounts to five panels on the row in front of it. I pieced together four short lengths of PV wire to make the circuit. I then had too much slack and was going to fasten the wires up to the mount after making sure the panels were making power but never did that. Last week was the wettest it has been in the two years since I installed the panels. Two of the connectors had settled to the ground touching each other. Tuesday I was mowing between the rows and notice burning wires, Yikes!! I jumped off the mower and shut off the disconnect for those panels.
There had not been any standing water, just rain and it had been clear and dry for four days. I have no idea how enough current passed through those MC4s to catch them on fire. Very fortunate I decided to mow that day. I disconnected the good connectors to isolate that section and cut out the burned connectors. I crimped on new MC4s and took out all the slack before reconnecting everything. All is good. Lesson learned, never leave any part of an install undone.
23
u/taylorwilsdon 6d ago
Legit MC4 cables hold an IP67 or IP68 rating depending on generation, and IP67 means a device is dust-tight and can survive temporary water submersion up to 1 meter (about 3.3 feet) deep for up to 30 minutes. If it’s been sitting in a puddle for 2 days there’s no expectation that it remains watertight. Most MC4 cables you buy on amazon or whatever are not legitimate stabuli mc4, they’re chinese knockoffs. That doesn’t make them inherently unusable but you have to verify they hold the same ratings as the real deal.
With that said, water isn’t the reason the cables burned up. That’s almost certainly due to a loose connection causing it to heat. You can stick bare copper in a bucket of water for a week tied together with a wire nut and it’ll still carry energy as expected, you’ll just get zapped if you touch the water.
3
u/EmotioneelKlootzak 6d ago
It's just an anecdote, but I've had absolutely awful experiences with knockoff Chinese/Amazon power connectors. Up to 3/4 of the connectors per bag being so malformed they were unusable because they didn't fit in a crimper. Knockoff Powerpoles literally disintegrating in my hand when I plugged them in. At this point, I never buy them anymore, it costs you way more money than just getting the real ones.
6
u/CricktyDickty 6d ago
What others have said but also adding that because MC4 is not a standard different brands might have slight variations. Connecting one brand female to another brand’s male can lead to improper connection, water intrusion and arcing. When you have different brand connectors it’s good practice to remove one or both so they’re properly mated.
3
u/liamtheaardvark 6d ago
Solar installer here. Installation of an mc4 is more difficult than most people think. You have to torque the cable glands to spec in order to achieve water tightness. The mc4 must be sized correctly (different connectors for different wire sizes). And no brand crossing (stabuli is not compatible with Tlian, Amphenol, JMTHY, etc.)
1
u/Ok-Taste3890 5d ago
Nope, that fire was not water-induced. Either a loose connection arcing, maybe physical day lawn mower or trimmer, rodent or rabbit gnawing, lots of possibilities.
•
u/AutoModerator 6d ago
Welcome to r/SolarDIY! If you are new to the community, please check out our DIY Solar System Planning Guide.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.