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Where is Ground?

Z

zalzon

Jan 1, 1970
0
Hi,
I bought an anti-static wrist band so as not to zap the components
I'm working with. It has a 1Mohm resistor. After I've put the wrist
band on, where do i attach the alligator clip to?

I've heard I should attach it to the "neutral of an AC main" is that
true. The thought accidentally attaching myself to the wrong outlet
pin scares me.

I know that the material i attach it to should have fewer electrons so
the electrons in my body flow to that site. But ideally should the
material be an insulator like wood/plastic or a or a conductor like a
metal?

Thanks
 
A

Arthur Jernberg

Jan 1, 1970
0
Either the neutral pin of the AC mains or a cold water pipe. Or you may want
to put a ground rod outside your building and run a copper lead to your work
area assuring absolute ground potential. Normally the Neutral of the AC
mains or Cold Water (Galvanized or Copper) Pipe will suffice. .
 
L

Laycock, Christopher

Jan 1, 1970
0
You need to be connected to earth. In the UK by the earth (green and
yellow).
 
B

Bob Masta

Jan 1, 1970
0
Hi,
I bought an anti-static wrist band so as not to zap the components
I'm working with. It has a 1Mohm resistor. After I've put the wrist
band on, where do i attach the alligator clip to?

I've heard I should attach it to the "neutral of an AC main" is that
true. The thought accidentally attaching myself to the wrong outlet
pin scares me.

I know that the material i attach it to should have fewer electrons so
the electrons in my body flow to that site. But ideally should the
material be an insulator like wood/plastic or a or a conductor like a
metal?

Thanks

If you are working on something with a metal chassis, you
can just clip to that chassis. Some people use a big mat
of conductive foam on top their workbench (if the benchtop
isn't already conductive) and clip to the mat.

The idea here is not so much to get yourself to any
absolute potential, but to the ground potential of
the circuit in question. If you connect to an earth
ground and your circuit (for some strange reason)
had a high static charge, there could be destructive
current flow when you touched it. But if you are
connected to the circuit ground, that can't happen.


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
D

default

Jan 1, 1970
0
Hi,
I bought an anti-static wrist band so as not to zap the components
I'm working with. It has a 1Mohm resistor. After I've put the wrist
band on, where do i attach the alligator clip to?

I've heard I should attach it to the "neutral of an AC main" is that
true. The thought accidentally attaching myself to the wrong outlet
pin scares me.

I know that the material i attach it to should have fewer electrons so
the electrons in my body flow to that site. But ideally should the
material be an insulator like wood/plastic or a or a conductor like a
metal?

Thanks
Exactly don't trust the neutral. Neutral opens back at the panel or
along the route and you might have line at the wire leading to the one
megohm resistor (which would keep you from frying as long as you don't
touch the wire on the other side of the 1M).

First choice would be the chassis if it is metal and grounded, second
choice is still the chassis if it is say the return of the internal DC
supplies. Clip to the low voltage isolated internal supply rail
return (DC minus most times).

The object is that your potential be the same as the device you are
handling. If you are connected to the neutral and the device is at
some other potential you could still destroy it. So an unplugged
device is floating at some potential - you want to be at the same
potential. I usually just touch the chassis before plugging in a
computer card, memory, etc..
 
S

Steve Dunbar

Jan 1, 1970
0
zalzon said:
I bought an anti-static wrist band ... where do i attach the alligator
clip to? I've heard I should attach it to the "neutral of an AC
main" . ... The thought of accidentally attaching myself to the wrong
outlet pin scares me.

You should connect to the AC ground, _not_ the neutral. The ground is the
round hole below the two parallel slots on the outlet (in the U.S.) There
should be a green or bare wire connected to it.

See <http://www.esdsystems.com/whtpaper/index.asp> for more information.
 
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