Thread: discolored bus bar

I have attached two photos from the same panel. The first photo shows the left lug and service wire. The bar is discolored. The second photo shows the right lug. There were no other signs of overheating but I am not sure what other than a bad connection or overheating would cause this discoloration. Thoughts?

Similar Threads:

• Discolored busbar
• Discolored water, galvanized pipe
• Discolored water
• discolored cpvc on water heater
• Discolored water

Common issue with GE panels.

Discoloration by itself is usually not a problem but the two nuts that connect the bus bars to the main breaker can be loose which cause some heat buildup in and around the main breaker so that should be checked.

More info here:

http://www.inspectionnews.net/home_i...ed-busbar.html

Originally Posted by Bruce King

Common issue with GE panels.

Discoloration by itself is usually not a problem but the two nuts that connect the bus bars to the main breaker can be loose which cause some heat buildup in and around the main breaker so that should be checked.

More info here:

http://www.inspectionnews.net/home_i...ed-busbar.html

Thanks, Bruce. I was going to point out that the anti-corrosion paste does not look like it has melted, so there's no evidence of heat, just tarnish.

Two things made me hesitate on the overheating idea. The scratches on the bar would seem to indicate the discoloration is surface only and no sign of melting on the plastic standoff.

Thanks for the thoughts. I do not have any other photos. I too am hesitant to believe it was caused by overheating. My clients need to consult an electrician anyway for other items found so I told them to have him look at this area and ensure a good connection.

Really difficult to tell but the upper left corner of the bar in pic #1 looks melted, perhaps from arching at some time. Are my eyes playing tricks on me?

Have found loose connecting rivets on buss bars. Note that the right side doesn't show signs of discoloration.
Reason would follow that the apparent overload or overheating is on one line only (left). It's possible that the conductor has been changed, otherwise we should see evidence in that regard.

I had something similar, was lightening that caused the panel I saw.
Outside extension to a backyard heat light to a dog pen hanging over a chain link fence.
Lighting hit a tree ran into the fence and the extension cord back into the panel.
Found the outlet was charred and a few electronic devices sharing that circuit inside was fried.
Looked like flash over from the main lug to the grounded panel itself.

Mike. That is an interesting idea. Here in CO we see a lot of lightning.

I too see what I believe to be melted/vaporized concern.

See also evidence of broken/melted strands to the left in the concentric bare aluminum strands, immediately to the left of the bar.

I too suspect a momentary prior arc, plasma or short event. Without better pictures and info hard to say. Stripping looks uneven and unprofessional. May be pulled tight now, and restripped/attached after prior event.

"Service Wire" so this is a service panel, no intermediate service disconnect?

I think you're misunderstanding what you are seeing.

There are two common 'causes' of such discoloration, that have nothing to do with the materials overheating in use.

The first is the manufacturing process, where the various processes used to form the metal can cause such discoloration.

The other is the result of a common light-duty corrosion protective process known as 'irridite.' This plating process results in a transparent finish that will vary in color in direct proportion to the thickness of the coating and the angle from which it is viewed. All manner of reds, blues, yellows, and purple shades can be found.

Thanks John for your insight. There is always a fine line between being over cautious and making sure all items that should be documented are. In this case I believe you are correct and knowing that these types of conditions happen through the manufacturering process will allow me to not call the item out in the future.

John S., we acknowledge your other reasons for discoloration however, I think it obvious that the right side would be of the same persuasion.

I still believe (98 %) is some sort of flashover, from lightning or other conductor came in contact with.
Overheating would seem to discolor the lug itself.
Maybe some of those extra wires on that neutral cut off before termination if not lightning ?
I have done enogh electrical work and seen other similar to this caused by lightning most of the time that look like that.