Dean

ESD can vary between 200 volts and 2,000 volts. If the computer case is 
not grounded, there is a risk that the charge could reach some internal 
electronic computer components before dissipating into the atmosphere. 
And, once the power supply itself is turned off, there is no electricity 
reaching the internals, but the remaining connection to a grounded 
outlet provides a ground for the case. Of course working in the power 
supply itself is an exception.

See   http://www.build-your-own-cheap-computer.com/static-electricity.html

Tom Mayer


Dean Kukral wrote:
> I disagree that to ground through the case (either by touching or by using a 
> wrist strap) that you should have the power cord plugged in.
>
> Just the opposite.  Unless  you know what you are doing, you should never 
> have the power cord plugged in when you are working inside an electrical 
> device!!!
>
> The purpose of touching the case and/or using a wrist strap is to drain 
> static electricity off of yourself so as not to damage any integrated 
> circuits.  There is absolutely no need to have the case plugged in to serve 
> as a ground.  Static electricity (free electrons) will tend to spread 
> themselves out on the case and drain themselves off quickly at the corners 
> and other sharp points.
>
> Dean Kukral
>
>
> ----- Original Message ----- 
> From: "Thomas Mayer" <[log in to unmask]>
> Sent: Monday, August 14, 2006 11:56 PM
> Subject: Re: [PCBUILD] New here, need help BADLY!
>
>
> You can either get a grounding wrist strap or, follow Thomas Harold's
> suggestion to touch the case often as you are working. However, to
> ground through the case, the power cord should be plugged in, if it is a
> 3 wire grounded connection, and then turn the power switch off on the
> power supply and not just the case. Of course, no matter which method
> you use, it is always best way is to avoid touching any contact points.
>
> Tom Mayer
>
>
>
>   

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