From: firstname.lastname@example.org (Floyd Davidson)
Subject: Re: Static Electricity!!!!!
Date: 4 Dec 1999 18:27:46 GMT
Allied Signal Aerospace <email@example.com> wrote:
>One of our field offices is having horrible trouble
>with static electricity. They've destroyed two hubs,
>and now their Cisco 2610 is a doorstop!
>Roughly, what precautions can I take, to prevent this
>from happening again, apart from making sure the 110v.
>outlet is grounded.
>Any ESD specialists out there who can tell me how to
>ground my router, as well as the T1 outlet box (extended
>demarc) to avoid getting zapped??
There are some very good (and absolutely interesting)
videos available on this subject. I've seen what Nortel
had 15 years ago, what AT&T had 10 years ago, etc. etc.
Everyone should receive at least some minimal training or a
briefing about Electro Static Discharge. Odd things that people
would not normally expect to be a problem are deadly. Putting
circuit cards or components into non-conductive plastic bags,
attaching paper notes using tape, setting equipment on top of
paper or other insulating material... are all asking for a
static charge to build up on the equipment, which will then be
discharged when a person picks it up or installs it into a
grounded rack. The mechanism is a huge voltage difference
between where ever the charge builds up and other non-charged
places; and then, when contact is made, there in a huge current
flow as the static charge is equalized between the two places.
That current is what destroys the equipment.
The trick is to avoid anything which allows a static charge
to build up in the first place. That is done by making sure
that even very small charges will be dissipated and evenly
distributed to everything.
You must control the relative humidity in your environment
to make sure it isn't too dry.
You can make sure the flooring is right. No rugs or other
material that is a collector of charged particles. Conductive
floor tiles, or a floor with conductive mats is the best.
You can assure that all equipment and racks are properly
One common building ground,
One common ground for each floor,
One common ground for each room if appropriate,
One ground bus from the common ground to each row
of racks and a copper ground bus across the top
of the entire row of racks.
Each rack has a common ground strap to which every piece
of equipment is grounded. That strap can be the
common copper bar across the entire row (usually located
at the top of the rack, or it can be a strap or wire
that runs down the length of the rack (or both can be used).
(All of the above is relatively easier and neater with open
racks, which tend to be the norm for the telephone industry, as
opposed to enclosed racks.)
You can assure that multiple personnel grounding straps (i.e.,
wrist straps) are available at every equipment location, and
that people utilize them _before_ touching equipment. (If you
want to get _really_ serious, everyone should wear an ankle
bracelet to make a connection between them and the conductive
mat on the floor too.)
Then all equipment must be handled in appropriate ways when not
in service. Cards or equipment should only be placed in or
removed from anti-static wrap or containers while the person
handling the equipment is using a ground strap.
And... test the ground straps on a regular basis! Every six
months or a year have someone measure the resistance. If the
resistance is too low they present both a serious danger to
people wearing them and to equipment, and if it is open (too
high) the danger is for the equipment being handled.
Floyd L. Davidson firstname.lastname@example.org
Ukpeagvik (Barrow, Alaska)