schneider wiring failure

flpilgrim · Feb 3, 2024

Well f&ck me running. Is this my fault? I had everything torqued properly and it was my understanding i could wire thhn directly into my battery terminal blocks. Southwire said 1/0 cable but 1 gauge was all i could fit in the block and the manual says to just follow local code for wire sizing.

Conext MPPT 100/600 to my xwpro. Noticed a burning smell this morning after pushing only about 3.4kw through for two hours or so. systems been up and running for a month with no problems; not even a whiff of anything wrong till this morning. No events on the mppt log. Around 6kw/90a had been my max output during peak hours.

Godd@mmit. I assume this isn't fixable.

Anything I should know to help avoid this in the future? My ego's bruised thinking i did something wrong but be brutal anyway please, i need to make sure this doesn't happen again.

TIA.

Quattrohead · Feb 3, 2024

I am going to say that you did not re-torque the screws and the multi-strand cable eventually worked loose and started to burn up.
You have to go back after a few days or a week or two and retighten the terminals, you will always be able to tighten them more. Ferules mostly negate this problem.

flpilgrim · Feb 3, 2024

Well fooey. i read that manual sixty times and must've missed that part. is this just common knowledge?

robbob2112 · Feb 3, 2024

Did you use a ferrule on your cable end? Or is the connection the type with the where the screw presses a plate down when you tighten it so you can put stranded wire in it?

AW560030 - 0 & 1/0 AWG Insulated Ferrule - 30mm Olive Green

A Wire Ferrule is a connector used to terminate stranded wires (sometimes referred to as a cord end terminal or bootlace ferrule). Traditionally a wire ferrule is crimped to a stranded wire using a crimping tool (compression, ratchet, or pneumatic mechanism), thus turning the stranded wire into...

www.ferrulesdirect.com

NOTE: it is pretty easy to get the screw terminal connector and replace it on the board. The PITA part is you have to remove the board to solder the new one on. And chances are the orginal solder was flowed on so you have to use a bunch of rosin core added to get it to melt so you can remove it.

400bird · Feb 3, 2024

flpilgrim said:
Well fooey. i read that manual sixty times and must've missed that part. is this just common knowledge?

Either common knowledge or hard earned lessons. I'm not sure it's in the manual. I got lucky and failed an inspection and found out before anything burned up.

I'll bet it is fixable if you source a replacement terminal block and solder it in place of that one.

flpilgrim · Feb 3, 2024

robbob2112 said:
Did you use a ferrule on your cable end? Or is the connection the type with the where the screw presses a plate down when you tighten it so you can put stranded wire in it?

AW560030 - 0 & 1/0 AWG Insulated Ferrule - 30mm Olive Green

A Wire Ferrule is a connector used to terminate stranded wires (sometimes referred to as a cord end terminal or bootlace ferrule). Traditionally a wire ferrule is crimped to a stranded wire using a crimping tool (compression, ratchet, or pneumatic mechanism), thus turning the stranded wire into...

www.ferrulesdirect.com

NOTE: it is pretty easy to get the screw terminal connector and replace it on the board. The PITA part is you have to remove the board to solder the new one on. And chances are the orginal solder was flowed on so you have to use a bunch of rosin core added to get it to melt so you can remove it.

thanks, i did not, its a stranded wire type pinch plate...if i had known i would have and ill do the next one differently.

Supervstech · Feb 3, 2024

Most manuals will require fine strand conductors.
Thhn is what7 or 16 strnd?ya need like 120 strand.

flpilgrim · Feb 3, 2024

400bird said:
Either common knowledge or hard earned lessons. I'm not sure it's in the manual. I got lucky and failed an inspection and found out before anything burned up.

I'll bet it is fixable if you source a replacement terminal block and solder it in place of that one.

thanks for sharing, i feel slightly less stupid now. it's definitely not in the manual.

flpilgrim · Feb 3, 2024

Supervstech said:
Most manuals will require fine strand conductors.
Thhn is what7 or 16 strnd?ya need like 120 strand.

it was my understanding that the opposite is true.

sollap · Feb 3, 2024

That connector looks like a Phoenix Contact 1932588.
You could take some measurements to be sure. Here's the datasheet: https://www.phoenixcontact.com/en-u...ard-terminal-mkdsp-25-2-1500-1932588?type=pdf
Mouser has them in stock: https://www.mouser.com/ProductDetai...=sGAEpiMZZMvPvGwLNS6711xdDG8CWmRFvv7fu4H6Srk=

dougbert · Feb 3, 2024

Quattrohead said:
I am going to say that you did not re-torque the screws and the multi-strand cable eventually worked loose and started to burn up.
You have to go back after a few days or a week or two and retighten the terminals, you will always be able to tighten them more. Ferules mostly negate this problem.

I learned (from YT https://www.youtube.com/@ElectricProAcademy)

torque once
loosen
move conductor back and forth
torque again

do that 3 times

it allows strands to fill voids

and yes, ferrule on fine strands all the time

scrubjaysnest · Feb 3, 2024

Even the county inspector recommended to retighten the connections.

robbob2112 · Feb 3, 2024

General rule of thumb is use a ferrule on fine stranded wire and for stuff like thhn you can just use the pinch plate. Fine stranded tends to spread a lot and work part of the strands to the edges where they are loose.

400bird · Feb 3, 2024

sollap said:
That connector looks like a Phoenix Contact 1932588.
You could take some measurements to be sure. Here's the datasheet: https://www.phoenixcontact.com/en-u...ard-terminal-mkdsp-25-2-1500-1932588?type=pdf
Mouser has them in stock: https://www.mouser.com/ProductDetail/Phoenix-Contact/1932588?qs=sGAEpiMZZMvPvGwLNS6711xdDG8CWmRFvv7fu4H6Srk=

Nice find! Coming in to save the day. A little verification and soldering from the OP and they'll be good a new.

Skypower · Feb 3, 2024

I’ve found loose terminals hundreds of times in my life and a few damaged large outlets. Pretty much, if I’m there, I’ll check them. Some terminals are just worse than others. For instance this generator inlet. The construction looks very high end. I used 6AWG thhn and orbit the wires a bit as I smoke the screws down. I checked it a few days later and I was surprised how loose they were. A few weeks later I checked again and they could snug up a bit more. It’s been a few years now so guess what’s on my to do list tomorrow?

robbob2112 · Feb 5, 2024

robbob2112 said:
General rule of thumb is use a ferrule on fine stranded wire and for stuff like thhn you can just use the pinch plate. Fine stranded tends to spread a lot and work part of the strands to the edges where they are loose.

So, reading other posts it seems the use of ferrules is sometimes hotly debated depending on the type of terminal block. I need to deep dive and learn the rules.
Most mentioned is on victron equipment where ferrules are not to be used, but they have a very different terminal block than you.

It seems tto be the rule is use ferrules in screw terminals and don't use them in spring terminals.

schneider wiring failure

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