OT (most likely) strange modem disconnection when using USB drives

[Tim]

Tim:
>> There's 240 Volts on the mains supply pin, the return and earth connect
>> together at the distribution box.  Plugs can only be inserted one way,
>> thanks to the angle of the blades.

Mikkel L. Ellertson:
> One thing that can be interesting is the voltage difference between
> the ground connection on two different outlets. There should not be
> any, but in practice there is always some. It when the difference is
> more then a few millivolts that you run into problem. You can also
> run into problem if the difference between the earth and return
> wires or between 2 return connections is too great.

When we've done productions in theatres, we've found several volts
across the earth wires when we've had equipment connected together that
was a couple of rooms apart.

And I've seen those light switches with little neon indicators to show
which is on glowing when power is running through a cable running
adjacent to them.  ;-)

> Now, when it comes to touching how wires, remember the old
> electrician's trick - touch with the back of your finger. The shock
> will make your mussels contract, and break the connection. This is
> especially important with DC circuits, as you may not be able to let
> go if you do it the other way.

Absolutely.  I just swished the hand past the wires, catching it against
the back of my finger.  So, (a) I was already going to be breaking
contact, (b) I would further break contact if zapped.  Don't try that at
home...

Probably the worst way is when you get a zap while screwing together
wall sockets which you thought were isolated.  You've got a firm grip on
your screwdriver, and you're holding hard against the socket.  Most of
the older insulated screwdrivers didn't insulate all the way down to the
tip.

TV servicing is another bad one, where you're reaching into the guts of
a set, and it's next to impossible to avoid touching things around you.

-- 
[tim at bigblack ~]$ uname -ipr
2.6.22.9-91.fc7 i686 i386

Using FC 4, 5, 6 & 7, plus CentOS 5.  Today, it's FC7.

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