Looking for some feedback please. I noticed an oil-like residue on some branch wires and breakers inside a panel box today, and I wondering if anyone knows what this might have been. It was actually dripping in places. Don't think it was water. Thx-Joe
JoeJoe, I have seen this before serveral times. If you are sure it didnt come from the outside, I would say it is plasticiser (DINP, DEHP etc) coming out of the PVC insulation. It's a quality problem from the wire manufacturer that makes it dissolve from the PVC.
It looks like a thin film of oil and can be so much that you see drops hanging from the wires. The inuslation will eventually harden and lose its breakdown specifications. You should perform insulation measuring on the site and think about replacing the wiring if values are bad or it looks to messy.
There are a few interesting effects. One is that the copper conductor is discoloured (oxydised) even in relatively new wire. The process is known to the manufacturers and considered harmless if the conductors are cleaned before they are terminated. I have seen affected wires from ca. 1960 that were still fine electrically and mechanically.
Only in one case the corrosion was severe enough to cause problems, the moulded trailing socket of a late-1950s extension lead actually covered the pins of an inserted plug with green slime. I never bothered to measure contact resistance but I'm convinced it would be far too high.
Yup, Plasticiser, is what that is. We had a problem over here with the earlier PVC cables installed in the 60's and 70's. My boss when I was an apprentice got some in his eye (why you'd rub your eye with that on your fingers, I have no idea, but there you go.) It's like oil, because PVC itself is made from petroleum products. I once had some pictures of this stuff (it was coloured green here, because it was corroding the bare earth wire in the cables) running out of the earth slot of a socket-outlet here and down the wall, it gets worse during the summer months when wall temperatures are higher.
I've read somewhere online that the same thing (green goo dripping out of sockets) happened in the UK as well. As I said I've had that happened with a very old extension lead (must have been one of the first designs using moulded plugs and trailing sockets). All other instances were rather harmless, the conductor surface was slightly discoloured (the typical brown of copper oxide) but cleaned up nicely and existing connections did not show any impedance issues, in spite of being over 50 years old in some instances.