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Baltimore Francis Scott Key Bridge collapse

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NiHaoMike:


If that does indeed turn out to be the cause, that would be the most costly connector failure in history.

coppercone2:
Ah the highly regarded wago style connector.

People really hold them in high regard

floobydust:
I've spec'd and used the Wago spring clamp terminal blocks to 40A (PCB) and they are excellent. They are typically used with wire ferrules. Used on locomotives because temp cycles and vibration cause screw-type terminal blocks to loosen with age. Unpopular in North America though, compared to Europe.

If a bonehead twists the screwdriver (instead of just pushing it in) to open the clamp, or uses the wrong size screwdriver, or pry's, it can wreck the terminal block inside by deforming the spring.
I would suspect that is what happened, improper assembly.

When panels are being built, we have a "tug'n tighten" requirement that you tug on all wires after assembly. I've had a few electricians with weak hands leave screw-terminal wiring really loose (just like idiot crimp-connecting) and the wire pulls out.
If I find a few loose connections, I flip out and demand everything gets re-tightened or re-crimped.

Out in the field, I have encountered control panels full of loose wires and spent 1/2 hour redoing all, which gets rid of many problems.

Other brands of spring clamp I've tried are crap. Hear that Weidmuller lol.

coppercone2:
some people on the forum were saying that it turns out the dumb american wire nut has a kind of welding action going on akin to wire wrapping which improves its reliability compared to wago connectors if used properly. The ones with the metal spiral inside


Two wires being pushed into each other by a spring that digs into them and also compresses them actually seems pretty advanced to me, if you think about it. There is no piece of sheet metal in the circuit, like wago.


Unlike crimps, you have very high point pressure (great contact) in a structure thats not been yielded. It is in the spring region the whole time and it does not desperately want to relax. A crimp exceedes the yield pressure of the metal to form. A wago is also in the spring region but it does not have that sharp edge (possible cold weld) wrapped around the wire...

SiliconWizard:
At this point anyway, the most likely culprit looks like a maintenance issue (maintenance badly executed). Which is quite often the culprit in aviation accidents as well.

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