From: dh0496@windstream.net   
      
   On 1/26/20 4:09 PM, Michael Moroney wrote:   
      
   > 3ɸ should be 208V/120V.  For three phase, phase to phase voltage is √3   
   times   
   > the phase-neutral voltage.   
   >   
   > Same for 480V.  It is really 480Y/277V, but 277V single phase is rarely used   
   > except for industrial lighting.   
   >        Just to add to the knottiness.      We have  three versions of   
   three phase power for irrigation here in central Nebraska.   
       The Y configuration has 277 volts to ground on all three legs. Two   
   lines in any combination read 480.   
     The corner ground delta has two lines reading 480 volts to ground and   
   between each other.  The third line reads 0 volts to ground.   
      The center tap delta has one line that reads 415 to ground.  The   
   other two lines read 240 to ground.   The hot lines all read 480 in any   
   combination to each other.   
      One of those configurations lets the utility use two transformers to   
   supply three phase.   
      
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