Inside this cuttler-hammer panel in the basement of a 1904 farm house all the exposed copper wire has turned to a pale grey color. I suspect fertlizer was stored in the same room causing the discolorization. This is the 1st time a can remember seeing this, but have read about it and understand it can be caused by swiming pool chemicals, drug labs, chinese drywall, etc. Do you have any information on discolorization and if it is known to cause any problems. This is an after the fact finding missioin for me, because I'm calling for a sparky to take a look as there were a few other problems as well and my client is a relocation company. Click to Enlarge 88.04 KB Click to Enlarge 56.52 KB Click to Enlarge 90.83 KB