[Jukebox-list] "Grounding" ?

[Ron Rich]

Hi All,
  Due to the discussion of "3 wire cords", I have remembered that I have no idea how this concept works!  If someone has the answers, please inform me---
  A "3 wire" 117VAC ( also called a "U ground" ) socket having a black (or red), a white, and a green wire is said to be "grounded". The black is said to be the "hot", the white is said to be "the neutral", an the green is said to be "ground" (in the USA--colors--er, colours, differ in Europe, and elsewhere).
  The fact is that the "neutral" and the "ground" are ALWAYS tied together, somewhere, either at the building's power distribution box (Now required here, along with a "grounding rod" at least six feet long, pounded into the earth, and connected to the "green" wire), or by the power company at some point. To my way of thinking, this makes the green wire, in a "plug", un-necessary, except for the fact that the ground "pin" of all 3 wire plugs is longer, and in theory, will "make" contact prior to the hot contact.  
  I become even more confused (only possible for me !), when I look at what Seeburg did from the model 100"B",  thru at least the STD model. They used non-polarized, 2 wire, line cords in the B thru the LPC-1 models. However the internal power sockets were polarized. From the LPC 480, on up, 3 wire line cords, and polarized sockets were used. However, in all cases, the power cords to the "control center(s)" were non-pols ! Some of the amplifiers in the later models, when a "line cord" was used, had polarized plugs on them??? Also, the lamp cords used in the later products, tended to be the pol type.
  So my questions are--What good does the 3 wire cord do, since the white and green wires are tied together?  And, Why did Seeburg ( and probably others) use the non-pol 2 wire line cords for components??
  Ron Rich

       
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