late one : To earth, or not to earth..

Don Tillman don at till.com
Sat Jan 10 23:22:29 CET 1998


   From: LBucha5714 <LBucha5714 at aol.com>
   Date: Sat, 10 Jan 1998 13:35:12 EST

   Ok so I  just finished my power supply which IS mounted inside a
   metal chassis but I did NOT connect (to ground or anywhere else)
   the third wire (ground from 120VAC wall socket).  

[...]

   So do you feel this is something that I should just be wary of and
   proceed?  Or is this one of those "Hell Buck, I wouldn't be on the
   same stage with you and Twisted Metal Box of Doom" cases?

Why do it wrong when you can do it right?

The right thing is to have the chassis connected to the third prong of
the ac line, for shielding and safety, and have the signal ground
seperate from the chassis ground, for ground loop reasons, and have
the two connected with a low value resistor (say 10 ohms or
thereabouts) so that in the absence of any other ground connection you
won't be floating.  

Simple, easy, safe, no ground loops.

  -- Don



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