Jim Katen Posted September 10, 2020 Report Share Posted September 10, 2020 I've never seen this before. The MC cable was secured to a basement wall with some very attractive metallic & velvet wallpaper sandwiched between the two. The cable sheath just dissolved into a white crust. My best guess is that this is the result of galvanic corrosion, where the metal in the wallpaper acted as a cathode to the cable sheath, which acted as an anode. Any other ideas? Quote Link to comment Share on other sites More sharing options...
Marc Posted September 10, 2020 Report Share Posted September 10, 2020 Is that cable clamp touching the panel enclosure? Energized sheathing from leakage on the load side? Quote Link to comment Share on other sites More sharing options...
BADAIR Posted September 10, 2020 Report Share Posted September 10, 2020 (edited) other factors causing the rust & staining makes me suspicious of just galvanic corrosion i've seen similar evaporating MC in commercial from rats or mice using the cable as their highways & byways their urine isn't metallic friendly Edited September 10, 2020 by BADAIR Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted September 10, 2020 Author Report Share Posted September 10, 2020 The whole area was very damp. You can see a bloom of green mold at the upper left side of the 1st picture. However, I saw nothing to suggest any other corrosive substances. I'm not sure why leakage of current would matter? Quote Link to comment Share on other sites More sharing options...
Marc Posted September 11, 2020 Report Share Posted September 11, 2020 (edited) 4 hours ago, Jim Katen said: The whole area was very damp. You can see a bloom of green mold at the upper left side of the 1st picture. However, I saw nothing to suggest any other corrosive substances. I'm not sure why leakage of current would matter? You can use a wet cell to produce electricity or you can use electricity to promote galvanic action. I know its alternating current but it can promote galvanic action half the time. Edited September 11, 2020 by Marc Quote Link to comment Share on other sites More sharing options...
John Kogel Posted September 11, 2020 Report Share Posted September 11, 2020 Maybe having a charge on the conduit would discourage the rats. I'm with Barry, piles of turds on top of the panel box, no doubt. I can smell that place from here. 🤓 Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted September 11, 2020 Author Report Share Posted September 11, 2020 Actually, the place was relatively rodent free (for Portland, which should really be called "the city of rats.") I'm certain that urine was not at play here. Quote Link to comment Share on other sites More sharing options...
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