ESD Protection (continued...)
buildup cant be completely eliminated, there are precautions
you can take to reduce the possibility of damaging components
due to electrostatic discharge. You should always ground yourself
to discharge any static buildup before touching anything inside
your computers case.
should never open the case on a power supply or monitor unless
you are qualified to do so and know exactly what youre
doing. You do not want to be grounded if youre
working inside a power supply or a monitor. There are capacitors
inside these units that store enough electricity to stop your
heart (even when unplugged). You should not open the case on
a monitor or a power supply. Please note that this is important
enough to tell you twice.
Antistatic Wrist Straps
An excellent way to prevent ESD damage to your computer is to
use an anti-static wrist strap. Its a conductive strap
that fits on your wrist as youre working. It has a wire
attached to it with an alligator clip on the end to connect
to your case or to an anti-static mat. Some can be plugged right
into the wall socket. Only the ground receptacle makes contact.
But make sure the cord is long enough, unless you have a receptacle
right at table level. If youre working inside a computers
case, the most important tool you should have is an anti-static
Note: A piece
of wire wrapped around your wrist and attached to the case does
not work the same. Anti-static wrist straps have a resistor
inside and are designed to slowly and safely bleed charges away.
At the very least, you should
use an anti-static wrist strap
connected to the bare, unpainted metal of your cases frame.
There are two schools of thought on this subject:
One is to leave your computer plugged in.
Any static buildup is discharged along your wrist strap to the
computer's case, then through the power cord into the ground
receptacle of your electrical outlet.
The second is to unplug your computer. With
the wrist strap attached, this should put you and your computer
at the same potential charge and no transfer of electrons should
This becomes a decision you have to make
for yourself. A lot of books will suggest that the computer
remain plugged in, and in fact, the A+ Certification exam considers
this the correct choice at this time (which is probably why
these books suggest it). However, when you leave the computer
plugged in, its a little too easy to turn it on when youre
working inside; or forget its on and plug in an expansion
card or drop a screw onto the motherboard. Also, you have full
AC power going to the remote power switch on the front of your
computer. If there is a bared wire, or open contacts on the
back of the switch, you could get quite a shock. Remember too,
that todays ATX motherboards have power to them even when
the switch is off.
A very good alternative is to plug your wrist
strap right into the ground receptacle of a wall socket, or
into a grounded antistatic mat.
Antistatic mats provide a grounded surface
on which to work or place components as you remove them. They
also have a cord that can be plugged into a wall outlet to slowly
remove any static charges. Some come
with another cord and a clip that attaches to your computers
case. The computer does not necessarily have to be on the anti-static
mat when youre working on it. If the mat is plugged into
a wall socket then its grounded. Attach an alligator clip
from the mat to the case, and now the case is grounded. Attach
your wrist strap to the case, and now any static buildup can
be safely discharged from your body. As you are working, any
parts you remove or plan to install, can be safely placed on
the anti-static mat.
If you find yourself in a
situation where you dont have a grounding mat or anti-static
wrist strap, then you should keep one hand on a bare, unpainted
portion of the chassis as youre working inside the case.
This method is not that reliable and youll soon find it
to be a little awkward. The ten or twelve dollars spent on a
good wrist strap is a wise investment.
Don't work on a computer or components when
they are cold. Allow them to warm up to room temperature first.
Cold, dry conditions promote static electricity. In the winter,
when it's very dry, static can build up very quickly. Raising
the humidity in your workplace can help to dissipate this buildup.
Humidity at 50% to 60% is ideal.
Keep components and expansion cards inside
their anti-static bags until you are ready to use them. Remember
to handle them carefully, by their edges and as little as possible.
Anti-static bags are treated to be conductive so that they draw
static away from the components inside. It's always a good idea
to keep a supply of anti-static bags to put expansion cards
and components into when working on a computer.
It's better to have a tile floor in your
work area than rug or carpet, which promotes static buildup.
Also, think about what you wear. You don't want to be working
inside your computer while wearing a wool sweater or a nylon
You may not be able to take
every ESD precaution all of the time, but use your head
and do what you can. The components and hardware inside your
computer are subject to electrical fluctuations, spikes, surges,
power losses, temperature extremes and, I suppose, even physical
abuse. But, the number one cause of damage to internal components
is Elecrostatic Discharge.