Hello, we recently purchased a 1947 home in St Paul for our daughter. I want to update the old outlets and switches, but have come across some odd wiring. The original rubber wrapped, cloth covered wire seems fine, but several swithches have an aditional "mystery wire" the switches of concern appear to be 3 way switches, but they each are only independantly running a single light or outlet. The mystery wire is vinyl coated and looks like typical thhn wire. This wire is neither hot, common, nor ground. I have capped off the mystery wire in a few of the boxes, installed new switches (breaking the hot wire) as one would normally wire a circuit and have found no consequence to the omitted wire (I checked all other switches and receptacles on the circuit in question)
Any ideas as to the purpose or origin of the mystery wire and 3way switch use would be appreciated.

 

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