RE: Lightning strikes Sears Tower (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 3 Sep 2007 15:37:34 -0700
From: Jim Mora <jmora@xxxxxxxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: Lightning strikes Sears Tower (fwd)

Hello Doc, et al,

Yes, local static control is a challenge in dry environments, PE like soles
develop up to 1" sparks into keyboards especially with plastic chair mats.
Lightning is not really off topic. Doing some fast research, Tesla holds a
patent on a non classic lightning arrester.

As far as high rises go, I'll bet a grounding buss goes straight down the
elevator shaft, hopefully well away from the data lines that now are
probably fiber.

Jim Mora

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx] 
Sent: Saturday, September 01, 2007 4:41 PM
To: tesla@xxxxxxxxxx
Subject: Re: Lightning strikes Sears Tower (fwd)


---------- Forwarded message ----------
Date: Sat, 1 Sep 2007 17:43:54 -0500
From: Dr. John W. Gudenas <comsciprof@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Lightning strikes Sears Tower (fwd)

Hi Jim
Off topic, but a unique experience.
I left Argonne Lab to join AMOCO (when it was AMOCO ) in the then new  
Standard Oil building  (now owned by an insurance company) located at  
200 East Randolph  over looking lake Michigan.
This building is essentially just as tall as the Sears Tower, albeit  
it does not have an observation deck. While the exact year escapes  
me, this was when high speed data links were problematic.

One technique used then to establish high speed data communication  
involved building your own line of sight microwave network and  
obviously if your organization built one of the tallest buildings in  
the world it made life easier.
I was part of the technical group that designed and contracted a  
point to point  microwave data communication link from Chicago to Des  
Moines. This operation took me to the top of the building until all  
was installed by the contractor. Imagine standing on the top of the  
Sears Tower and having a four foot wall to lean over that separated  
you from the edge. Yow!

Anyhow, there were lightning rods all over the place with heavy cable  
that went to a central ground cable. I don't really know where  and  
what that cable was connected to but it worked. It may have been  
connected to the steel building frame or it may have run 80 stories  
direct to an earth ground. I simply don't know.

I had three floors of IBM mainframes and numerous remote terminals  
located throughout the building. There were frequent strikes to the  
building during thunder storms and nothing would be disturbed by them.
Quite frankly,  static sparks from "static free" carpeting caused  
more problems for remote terminals then. I grew bored with managing  
projects and went back and picked up my Ph.D. Research and teaching  
is a lot more fun!
John


John W. Gudenas, Ph.D.
Professor of Computer Science


On Sep 1, 2007, at 2:20 PM, Tesla list wrote:

>
> ---------- Forwarded message ----------
> Date: Fri, 31 Aug 2007 23:40:28 -0700
> From: Jim Mora <jmora@xxxxxxxxxxx>
> To: 'Tesla list' <tesla@xxxxxxxxxx>
> Subject: RE: Lightning strikes Sears Tower (fwd)
>
> Hello List,
>
> I have often wondered: what sort of grounding systems are used for  
> these
> bolts - particular Positive Lightning? Has anyone had experience  
> with high
> rise grounding systems? It's hard to imagine all the computers  
> running in
> Sear's Tower without a twitch after such events. The instantaneous  
> magnetic
> field must be enormous.
>
> Regards,
> Jim Mora
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Tuesday, August 28, 2007 5:45 AM
> To: tesla@xxxxxxxxxx
> Subject: Lightning strikes Sears Tower (fwd)
>
>
> ---------- Forwarded message ----------
> Date: Mon, 27 Aug 2007 23:18:20 -0800
> From: Greg Leyh <lod@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Lightning strikes Sears Tower
>
> http://www.liveleak.com/view?i=27a_1187998916
>
> Of particular interest is the horizontal strike that passes completely
> through the view area.   GL
>
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