We recently bought a 1954 ranch house. This fall I began to pull out the old attic insulation and discovered several electrical wiring issues. The house has a mix of older wiring with a metallic jacket, newer NM wiring, and wiring run in conduit or BX. The wiring with the metallic jacket appears to be original to the house and is the source of my concerns.
I found several instances where the metallic jacket on the older wiring appears to be damaged. I also found a few instances where the older wiring was laying over the newer NM wiring, and the NM wiring has been discolored. I can't tell if the discoloration is staining from the old jacket or actually burn marks from the wiring. I've included pictures to help illustrate. Do I need to replace all of this older wiring? If I don't, am I risking an electrical fire or simply just losing current through the poor jacketing.
If I need to replace the wiring, how is this done without tearing apart the house? I assume all the wiring is tacked to the studs as it drops down the wall cavities. Can I simply replace the wiring in the attic to the point where it drops down the wall and then splice in a j-box? This eliminates half the problem but creates additional wire splices. Or is it possible to fish the wiring to each termination point?
Our home inspector walked the attic and didn't mention any concerns with the older wiring, so I assumed it was safe. Any input or advice is appreciated. Thanks.