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

Tue Jul 21 09:56:37 EDT 2009

Since Chad mentioned my name...Here 's a few thoughts. Some duplicates 
of Chad's.

We did have a few hits and lost a couple of PC's, telephone module, etc
Also some electronics in the main power distribution panel when a bird 
fried on the pole.

Point of interest.
A static spark from your finger to a doorknob can be over 6,000volts.
It can easily destroy or damage an electronic chip, depending on contact.
Lightning can be over 300 kilovolts for a few milliseconds.

With a direct hit it probably won't matter too much what you have.
Mettler-Toledo sold many truck scale protection kits in lightning prone 
areas and still lost load cells.
(Load cells generate low voltage signals representing weight changes.)

Always keep your insurance paid up !
Make certain the coverage is correct !
Keep your inventory list up to date and handy!

M-T headquarters has a nice setup for their workstations.
Each one has it's own special surge protected.power distribution box.
Some outlets were for printers etc. Ethernet and phone lines too if I 
remember correctly.
Special outlets for the PC and monitor went straight to a battery backup 
system.
It had a BIG battery bank and an outside emergency generator.

Fiber optic cables are very nice, they won't conduct surges.
Just having an Ethernet cable close to power cables could knock out a NIC.
As Ethernet cables are usually bundled from the rack you could easily 
take out every attached NIC.
Racks can come with built in surge protection,   for a few dollars more.
APC ProtectNet can be used at the PC

M-T always specified low voltage cables to be at least a foot away from 
AC cables.
Never directly next to a power cable and only cross at right angles.

So don't tie wrap Ethernet cables with the AC power cords because it 
makes a neat bundle.
Keep the mouse, k/b, and monitor signal cable separate too.
Definitely don't tie anything to the surge protector power cable!

Have the power company insure there is lightning protection at the pole 
transformer.
Add something similar to the main power distribution panel in the building.

Don't forget to protect the T1  (or whatever) cable and the alarm system 
phone line.
Maybe even consider 2 inline protectors.
An alarm installer saved his unit this way. The first one blew off the wall.
The second died to save his system.

Especially protect power and Ethernet outlets on outside walls.
We lost a  NIC and the a single port on the switch at the other end.
And the hit was waaaayy  over there somewhere.

Bob

R. W. (Bob) Neeper     Cell: (740)-407-3572 
Community Library
44 Burrer Dr.
Sunbury, Oh 43074
Tel:  (740)-965-3901

Chad Neeper wrote:
> 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
>>   
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