[GreenKeys] Color Codes??

[Roy Morgan]

At 05:23 PM 8/23/2004 -0700, Jim Walls wrote:
>Very common in 48VDC plant
>Black = return
>Red = supply
>
>Since 48V station battery plant (TelCo central offices, etc) are positive 
>ground, the red is positive and the black is negative.


Jim,

I was reading "the Green Book" recently, or perhaps an Army manual on 
teletype installations, and noticed that positive ground standard. I wonder 
if it was established like that to prevent corrosion in the battery room, 
or for some reason connected with telegraph open lines with earth returns.

Roy



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