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Re: [TowerTalk] Grounding a metal roof/Direct TV

Subject: Re: [TowerTalk] Grounding a metal roof/Direct TV
From: Jim Brown <>
Date: Tue, 27 Dec 2011 17:52:51 -0800
List-post: <">>
On 12/27/2011 3:47 PM, wrote:
> Anybody out there with some technical info on whether the grounding  is
> necessary to keep the roof at the same potential to everything  else.

Your exactly on target about keeping everything at the same potential. 
Good engineering practice says bond all metal together and to ground.  
Yes, I would definitely bond your metal roof.

> Also before I even got any towers up last summer, we got nailed  with a
> lightning hit that came through the Direct TV and took out our 60 inch  screen
> which was two days old.  Any place to get a Polyphaser for this that  won't
> break the bank?  I believe Direct uses around 1.2 gHz.

  I'd bet that the fundamental cause of your TV dying was either that 
everything was not properly bonded together, or that you had  MOVs on 
one or more of the branch circuits in your system. The shield of your 
Direct TV lead-in should be bonded to the power system ground, and the 
telco ground, and your roof antenna ground, and your ham antenna 
grounds, and all ground rods. As to MOVs -- the only safe place for an 
MOV in a power system is at the service entrance.

As to a lightning arrestor -- look at my White Paper on power and 
grounding for audio and video systems on my website for F-connector 
arrestors I found.

73, Jim Brown K9YC


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