On Sunday, January 20, 2002, at 07:29 PM, David Dudine wrote:

> To my knowledge, none of the computer brand surge suppressors use 
> anything
> except one or two little MOV's.  For networked computers, pay attention 
> to
> what the Brick Wall website says about diverting surge to ground and
> contaminating data lines.  They are referenced to the same ground plane.
>

The good computer UPS units don't let you run anything off the wall. All 
the protected outlets come straight off the internal battery, so there 
is no chance of a surge and the power is very clean. Plugging it into 
the wall just ensures that the battery stays charged. The network, 
telephone and non-powered outlets are protected by metal oxide varisters 
(MOVs) or zener diode bridges.

I've had an APS unit at home for several years and haven't had anything 
damaged by lightning since I got it. It protects the network, telephone 
and main computers. Before that, I'd have a modem or some other device 
go out every year when the boomers rolled through.

An added advantage of the APS-type units is that you can put monitoring 
software on your computer to do a graceful shutdown when the power goes 
down. My computers will stay up for five or ten minutes after a power 
failure, and then shut themselves down when they notice the UPS' battery 
has discharged too much.

You can get a pretty decent UPS for $150 or less, if you shop around.

---
Lee Larson, Mathematics Department, University of Louisville
Phone: 502-852-6826  FAX: 502-852-7132


The next meeting of the Louisville Computer Society will be January 22.
For more information, see <http://www.aye.net/~lcs>. A calendar of
activities is at <http://www.calsnet.net/macusers>.


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