Filesystem corruption (was: wiped disk - no longer bootable)

[Gene Heskett]

On Saturday 13 July 2019 16:32:04 Ralf Mardorf via ubuntu-users wrote:

> On Sat, 13 Jul 2019 18:51:29 +0200, Volker Wysk wrote:
> >I think they are called "Schutzleiter" (protective conductor), but
> >I'm not sure.
>
> That's correct, but as a matter of principle your fingers have no
> place in the outlet sockets, even not if you just want to touch
> perfectly correct wired earth. Hands off!
>
> An interesting question, where do we connect the anti static wrist
> straps, if need to fear colour blind electricians?

To the chassis frame of what you are working on. But perhaps I've not 
emphasized that the alligator clip and wire leading to the strap has a 
very high resistance between it and the strap, something generally in 
the 3 to 6 megohm range, and not a bulk carbon but something that can 
take the local wall socket voltage virtually forever.  Spiral cut in 
carbon film generally has a high enough long term voltage withstand that 
its chance of failing short are nil.  So the chances of receiving a 
lethal shock from a wrist strap is so close to impossible that the odds 
are very very long and don't enter into most calculations.

If in doubt, and you don't have one of the pocket sniffers handy, stand 
on a dry floor, and gently touch the chassis with the back of the hand 
in a slow rubbing motion.  Thats a very sensitive area, if the rubbing 
motion is dead smooth feeling, it should be grounded, but if a vibration 
can be felt as the back of the hand is sliding with a feather touch, its 
not properly grounded, and its time to get out a meter and see just what 
the heck you do have.  In the case of an old building you may want to 
carry a 50 foot roll of wire and a short metal rod you can step into the 
ground a foot, and use that for the meters common. Throw the rod and 
wire out the nearest window, step the rod into the grass, and connect 
the wire to it.  The rod of course should not be alu because the oxide 
may take 400 volts to penetrate, copper is best but steel is ok for 
this.  Pita to setup, but at least you will KNOW what you're dealing 
with.

Cheers, Gene Heskett
-- 
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 - Louis D. Brandeis
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