Busbar Colour Turn to Black

Did the bar experience a short-circuit that became the black-out, perhaps?

no overload or over current, black out was a planned. black out because we change a power suppy from ship to shore supply

Particles of combustion?

What material is the bar made of?

Soooo....it was all shiny and new before the power shift and then after it was all black and powdery?

I would put 2 and 2 together on this one. Sounds like someone crossed some busses somewheres and you got lucky that this was the only result!

Look for missing or vaporized connection lugs. Also look for evidence of shrunken or melted back insulation on cables attached to the bus bar.

The color and powder indicate something was vaporized. Any dead or fried critters (such as a rat) nearby? There was obviously something that caused a big arc.

Copper does have a black oxide too. (cupric) If the atmosphere was corrosive enough and/or the temp got high enough and providing it's a copper alloy, it's a possibility. And ther's always the carbon story version. But where the heck would you get carbon from? S.M.

Yes, extreme heating will cause copper to react with air to form this oxide. We have some of this in our panels but it comes after years of operation.

Has anyone seen this happen very quickly in any of their equipment?

Secondary to the vaporized component idea is one of corrosion, however it is not often something that happens quickly. So do you absolutely know for a fact that it was quick, or had nobody looked in that panel for a long time and only noticed it after the blackout?

So back to corrosion theory. Hydrogen sulfide (H₂S) in the atmosphere perhaps? Actually almost any kind of sulfide can cause a copper sulfide layer to form on bare copper bus bar and it is black and grainy. So anything that can out-gas sulfur can create sulfates and then sulfides. Even lowly little anaerobic bacteria can do that, but that would not explain it happening after a blackout (unless they took the opportunity to reproduce rapidly in the dark!). Much more likely would be outgassing of batteries that were on-line during the transition. Something like that.

But you didn't say if the bus bar was bare or plated. If it was silver plated, the things that turn silver black are different from the things that turn copper black.

that ship using copper type busbar

oxydation in copper is usually in green colour...when your bus bars turned into black....just meant your bus bars undergone a shorted bus...or sometimes caused by flashing arcs...

Oxidation of copper is green. I didn't say copper oxide, I said copper sulfide.

Click picture for source website and explanation.

sulfides, oxides, and what else???..the point here was to convey to the inquirer about that black colorization of their bus bar...meaning...its way too out of the topic...

Cupric...(a copper oxide)...is black.

"You dirty busbar! You killed my rat!!"

since the rat is dead shall we start a wild goose chase now? or look for the black cat in the dark room after it has gone away?

now lets get in the question mode . . .

the problem was first observed after you changed from ship supply to shore supply? ie was the problem there already earlier on?

or did it really happen during or after the changeover?

is the "black" some kinda amorphous dust that you can swipe off with a finger or piece of paper? if so then does swiping off leave a clean and original color surface? or a stained surface? is there evidence of heat in the form of rainbow like discoloration beneath or around the black?

since you mention change from ship to shore supply, was the ship supply without a grounded neutral? and the shore supply with a grounded neutral?

were any of the loads connected ie switched ON before connecting shore supply?

did any fuses or cbs operate? at what point in the circuit if they did?

these are for electrical engineers . . . other questions may be asked in a material science forum . . .