[OPLINTECH] Building question: isolated ground or at least separate circuits, and built-in surge protection

[Chad Neeper]

Excellent questions! With the exception of the server room and/or wiring 
closets:

Speaking from my own experience and observations, I'd suggest not paying 
particular attention to having isolated grounds or even necessarily 
isolated circuits for your general use patron and staff computers. 
Naturally, however, DO pay attention to the estimated load on each 
circuit. If it's intended to have a large number of workstation at a 
particular location (a lab, for instance), then of course you'll need to 
figure out how many computers you can have on one circuit and then have 
enough circuits run to keep your load WELL below the maximum loads. Same 
goes for anywhere that you know you are going to have devices (computer 
or otherwise) that draw power. This is an interesting read I stumbled 
upon with a quick Google search about IG systems and how they might NOT 
work as you might think. I suppose this could affect its use in a server 
room as well and worth investigating further, probably best with a 
full-blooded electrical/electronics engineer:

http://ecmweb.com/mag/electric_demystifying_isolated_grounded/index.html

Definitely food for thought, especially when you factor in the added 
costs of an IG system.

As for whole-building surge suppression, it would seem that a 
whole-building surge suppressor is a good way to go, but it would be 
wise not to rely on it completely. You should still use point-of-use 
surge suppressors to protect your more valuable items...computers, 
electronics, all the normal stuff, etc. You'll have to work with your 
general/electrical contractor to work out if you want circuit-based 
suppression or whole-building and to find out what options are available 
to you. While I don't know what commercial-grade whole-building surge 
suppressors are available, I suspect that you just might find the cost 
to be perfectly acceptable as a one-time cost insurance policy. (If 
lightning were to strike within 1/2 mile from the library, how many 
devices are plugged in 24/7 that might get fried or degraded. When the 
power goes out, or more specifically, when it comes back on again and 
"yo-yos" as it often will...how many devices are having their lifespans 
degraded and what is the cost to replace/repair those items? Think 
refrigerator, furnace control system, dishwasher, alarm 
system...anything electronic...) As for how common it is...Well, amongst 
my own library clients, not a single one currently has a whole-building 
or whole-circuit surge suppression. I can quickly name several clients 
that might have benefited from it, however!

Also consider the fact that your phone system is expensive/important and 
that power surges can travel just as readily into your library via a 
telephone line. If you protect the lines at the point they enter your 
building you just might save yourself a major expense and headache down 
the road. Again...I have several libraries that pop to mind here 
too...and, at the time, those each had only 3-4 analog phone lines that 
could easily have been protected with off-the-shelf protection just 
before they entered the multi-thousand dollar phone systems...for under 
$150 total. Those were hard-earned lessons! Actually, I think Bob Neeper 
might have been around for one of these incidents. He can attest to this 
one!

Same with network data cables...You can get surge suppressed rack-mount 
data ports to replace your "normal" rack-mount ports. But last time I 
looked, they weren't particularly cheap. Unless you have a smallish 
number of computers, you might be limited to protecting select 
computers. Seven or eight years ago Hurt/Battelle Memorial Library was 
hit with a direct lightning strike. At the time they had about 26 
six(ish)-month old computers. All but four or five had immediate damage 
to the network cards, with the mainboards failing completely shortly 
after. Having dutifully protected every computer with good surge 
suppressors, none of the power supplies failed during the period the 
computers remained in sporadic use. Thank goodness for good insurance!!!

Good luck!
Chad


-----------------------
Chad Neeper
Senior Systems Engineer

Level 9 Networks
740-548-8070 (voice)
866-214-6607 (fax)

--   Full LAN/WAN consulting services   --
-- Specialized in libraries and schools --



Phil Shirley wrote:
> Could you help me with these two questions about electrical systems for
> computer equipment?  We're planning a renovation of the main part of our
> library.
>
> 1.  Should we have electrical circuits with an isolated ground, or at
> least separate electrical circuits, for our computer equipment?  (I'm 
> talking about workstations around the library, as well as everything in 
> our server room.)  I assume the answer is yes, but early drafts of the 
> electrical plans do not have anything like this.  One of the EEs told me 
> that often, instead of having a true isolated ground setup, many places 
> will simply have separate circuits designated for computer equipment 
> (with orange outlets); supposedly, the ground noise that's caused by a 
> sweeper or something doesn't travel far enough to be of concern to a 
> computer on a separate circuit.  A little bit of searching suggests that 
> maybe a true isolated ground system is not necessary for most modern 
> computer equipment.
>
> 2.  Is it common to have surge protection built into the electrical 
> system, as opposed to plugging surge protectors into the wall and 
> plugging computers into those?  I'm told that it's possible to have 
> surge protection built into the electrical system in any of several 
> places, but I don't know if it's cost-efficient for most organizations.
>
> Phil
>   
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 3273 bytes
Desc: S/MIME Cryptographic Signature
Url : http://mail.oplin.org/pipermail/oplintech/attachments/20090720/1f9975bc/smime.bin