[TowerTalk] My situation: Is lightning protection needed?

[Jim Lux]

On 7/10/13 7:29 AM, Art Greenberg wrote:
> The discussion about protecting networked computers is of interest to me
> because I have been thinking about an application here. I thought I'd
> start a new thread about my particular situation to see what others think.
>
> I have an enclosed, air conditioned barn that I'd like to put my shack
> in. The thinking is, I'd run an Ethernet cable to the house using an
> existing buried conduit (that is now empty) and run the radio equipment
> remotely. The conduit run is about 230 feet. I figure a total run of 300
> feet or so to connect a switch in the barn to a switch in the house. Our
> Internet service comes into the house.

use 5.8 GHz WiFi with high gain antennas.  Inexpensive bridges 
available, etc.  100 meters of airgap is a lot of galvanic isolation<grin>



>
> The barn has its own electric service. There is a shunt-mode "whole
> house" surge arrestor installed in the load center. The service feeder
> to the barn and the service feeder to the house come from completely
> different directions. Both are above ground until they get close.
>
> The antenna transmission lines to the barn would all be run through an
> entrance panel with lightning arrestors, bonded to the barn's service
> ground. All of the radio equipment would be grounded to the entrance
> panel ground. The radio equipment would be very close to the load center.
>
> If I can get a reliable gigabit network running between the barn and the
> house, I could put some of my other computer equipment in the barn as well.

Gbit will be hard (impossible) with WiFi (100 Mbps is more like it), but 
you might look at some of the point-to-point microwave solutions. 
Wireless (where FO cable is "wire") is pretty nice, if you've got a 
decent line of sight without too many trees in the way. Some trees are 
ok, but dense woods will probably block the signal.

no cables to pull, no worries about the backhoe hitting the conduit, etc.



>
> I'm in Florida, near Gainesville. Lots of lighthing, particularly during
> summer.
>
> Long prologue. Now the question.
>
> I think its obvious that fiber would provide complete isolation between
> the buildings. But would a copper cable (Cat5e, Cat6) with lightning
> arrestors at each end be good enough? What strike scenarios would be
> problematic?

100 meters is a pretty long run for copper ethernet (it's at the maximum 
distance in the spec). And, by the time you buy and install all the 
protective gear you're probably at the point where fiber would have been 
cheaper and faster.

if you have overhead utilities now, what about overhead fiber?  You can 
get sunlight resistant FO cables and since they're non-conductive, you 
can string them just about anywhere you want, subject to any other 
safety (clothesline height is bad) or aesthetic (No cables across my 
backyard, thank you very much) concerns.  The stuff is really 
lightweight and strong because of that aramid strength member.