What if you have a faulty device in your house with a short (fault) to
ground?  It is **possible** for the ground wire to be hot, isn't it?  I know
it is not likely, and even if you got shocked, it would not likely be
serious, but for the average guy who works on his computer only now and
then, I think that a wrist strap connected to the case is the better choice.
The problem is ESD.  On a case with many sharp corners and edges,
electrostatic charge is quickly dissipated.

Are there any electricians out there who can tell us if I am being anal
about this?

Dean Kukral



----- Original Message -----
From: "Ian" <[log in to unmask]>
Sent: Wednesday, December 31, 2003 5:39 PM
Subject: [PCBUILD] Adding memory - grounding yourself


One final note about grounding for the benefit of anyone who wants to set up
a simple system in their workshop.

Find a nearby electrical outlet.  This can be a wall socket, strip connector
or extension lead - the principle is the same.

Switch off the mains power and open up the socket.  In most countries, the
setup is the same - you'll have a phase line, which is the 'hot' one, a
neutral line and an earth line.  The color codes vary for these - the 'hot'
line might be red or brown, the neutral might be black or blue, but the
earth wire is usually green.

Anyway, it's the earth terminal you need to locate.  Now get yourself a
length of appropriately colored, insulated single-core wire that's long
enough to reach from the socket to your workbench.  Undo the screw on the
earth terminal and attach, or 'patch in' one end of your loose wire.

Re-tighten the screw, making sure the original earth wire is still properly
connected.  Replace the socket or plug cover, ensuring that your loose wire
protrudes from under the cover.  Obviously, there are many ways you could do
this - select a method that is primarily firm and secure and secondly, tidy
and unobtrusive.

Now, if you've done it right, you'll have a direct link to your home's earth
wire circuit.  In New Zealand, this line goes directly from the switchboard
to a metal rod which is driven 6 feet into the ground outside the house.  A
branch line is also attached to any metal plumbing pipes so that taps etc
are properly grounded in the event a faulty hot wire comes in contact with
the metalwork.

Once you've set up your earth wire, attach the other end in any way that's
convenient for you to touch.  On my workbench I have a large bulldog clip
attached to the upstand at back of the bench and the earth wire is screwed
onto that with a self-tapping screw.  Periodically, while I work, I reach
out and touch the bulldog clip for a second or so.

But it would be just as effective to touch the bared end of the wire,
perhaps twisted into a loop or knot.

Note that I suggested using a single-core wire for the earth lead.  Our
electrical dealers sell a 1mm (about 1\16 inch) single copper wire,
insulated by a green plastic sheath, which is ideal for the purpose.

One final note:  Be extremely careful to connect your wire to the EARTH and
not the HOT circuit.  And if you're in any  doubt about this procedure,
don't do it at all.

Note that if you ever have to touch a suspected hot wire, be sure to use the
BACK of your finger or hand, not with your palm towards the wire. This way,
if the wire is live, your grip will spasmodically contract away from the
wire, not towards it.


Ian Porter
Computer Guys Inc.
Arrowtown
New Zealand
[log in to unmask]

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