From: moroney@world.std.spaamtrap.com   
      
   There is a long HVDC power line from northern Quebec Canada to Ayer,   
   Massachusetts USA. It operates at either +/- 375 kV or +/- 450 kV   
   depending on source.  As I understand it, it is grounded at exactly one   
   point, near Saint-Claude, Quebec. You can see it on this Google   
   satellite view: https://goo.gl/maps/bnsYcbv9Q3ewmkG49  where the power   
   line ROW runs diagonally on the right side, and the actual grounding   
   point is the weird circular shape at the upper right.  Additionally,   
   multiple conductors (6) run from the ROW to the circle.  The street   
   view at https://goo.gl/maps/K94ZceiRfUL2ePaU7 shows the huge towers   
   as well as 4 grounding leads, two at the top of the towers and two   
   others on wooden poles.  They are on rather substantial insulators.   
      
   Does anyone know any details for this rather odd setup? Why multiple   
   grounding conductors, and any details of the circular structure?   
   Do the grounding conductors carry current during normal operation,   
   perhaps with the line at half power with one side out of service and   
   the grounding (neutral?) carrying the return current?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)