XPost: sci.electronics.design, sci.electronics.misc   
   From: kraken.sankey@gmail.com   
      
   On 20/07/2022 07:53, Mike Mocha wrote:   
   >   
   > Hey all,   
   >   
   > Just curious what you think about this.  The photos at the link are   
   > showing large gauge wire used on a vintage 600 VDC rail vehicle.  We're   
   > talking 1930's electric streetcar technology.  Basically 600 VDC connected   
   > to a knife switch, then to a rotating manual controller which you   
   > partially see in the photo.  The rotation of it sets up the series and   
   > parallel stages to the traction motors.   
   >   
   > We see this weird rubber beading occurring on the outside of the older   
   > wire insulation.  I'm not sure what that insulation is made of or how old   
   > it is.  This only seems to occur on the older wires.  The newer NFPA   
   > compliant wires don't have this symptom.   
   >   
   > What is it and what causes it?  Any theories?  Thanks.   
   >   
   > https://imgur.com/a/OqHQV8U   
   >   
   Bits of melted tar maybe...   
      
      
      
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