Lightning Protection Question

T

Tap@Hawkelectric

Member
Location
North Salt Lake
Occupation
Master Electrician / Owner
I have 10 communication cables run from one building to another building the buildings are 25' tall what is the distance between buildings where no lightning protection is needed.
Is there a NEC 2020 Code Reference
 
Tap@Hawkelectric said:
I have 10 communication cables run from one building to another building the buildings are 25' tall what is the distance between buildings where no lightning protection is needed.
Is there a NEC 2020 Code Reference
Click to expand...
As far as I know, NEC does not cover this. This analysis is generally done with the Rolling Sphere method. One link to explain below:

Rolling Sphere Method For Lightning Protection | East Coast Lightning Equipment

The methodology behind the placement of air terminals atop a structure is largely based on what the industry refers to as the
ecle.biz

Mark
 
FWIW...........based upon experience in Broadcasting over 45 years:

'You can never have too much lightning protection'

Corollary 1 : You will never know if you have enough, only that you did NOT have enough'

Corollary 2 : Mother Nature WILL find the weakest spot in whatever scheme you implement.

Liberal use of these or similar products may help.

 
Thanks, for the information, but i took a test on Saturday and this question stuck in my head and it the distance between buildings.
in feet the answers, was 60', 75' 100' 140'
But nowhere I found those footage. when I google that same question I had an answer of 37.5' apart I am looking into NFPA 780 but I have not found it yet.
Bad Question is what I'm thinking.
 
Tap@Hawkelectric said:
Thanks, for the information, but i took a test on Saturday and this question stuck in my head and it the distance between buildings.
in feet the answers, was 60', 75' 100' 140'
But nowhere I found those footage. when I google that same question I had an answer of 37.5' apart I am looking into NFPA 780 but I have not found it yet.
Bad Question is what I'm thinking.
Click to expand...
Interestingly, that answer is exactly half of 75. Was there some confusion regarding radius versus diameter?
 
There is no 780.

All I can see is that 805.90(A) mentions "block" which is defined in Art 800 definitions. I do remember way back that there was some verbiage about building height and maybe distance but that is long gone. Protectors are required as close to the point of entrance as possible on either end of the circuits regardless of the distance. This just makes sense from an engineering standpoint with today's equipment.

So, yeah. That was a bad question.

-Hal
 
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