[ale] Off the Wall

[Joe Steele]

Besides the other recommendations that have already been posted 
regarding this topic, I'll mention something else:

The National Electrical Code has certain requirements for the proper 
grounding of coax cables which enter a building, particularly cables 
which are exposed to lightning or accidental contact with power 
lines.

The intent is to provide a safe path to ground for current surges or 
fault currents without having the current enter the building in 
search of some more hazardous path to ground (either through you or 
your equipment).

Cable TV was installed (from overhead service) at my house many years 
ago, and the cable company never bothered to ground the cable at all.  
Every time I disconnected the cable from the TV, I could feel a 
little tingle from voltage on its exterior shield.  I eventually 
installed proper grounding myself.

Although I don't really know, I presume my case is a rarity and that 
most cable installations are in fact grounded in some way outside the 
building.  What I have heard, however, is that a common mistake made 
by installers is to connect the cable sheath to a ground rod driven 
at a convenient location near the point of cable entry to the 
building.  The ground rod is then relied on as the *sole method* of 
grounding.  In virtually all but the rarest of cases, this does not 
satisfy the NEC.

Proper grounding requires that the cable be bonded to the electrical 
power grounding system serving the building.  The cable companies can 
install a ground rod if they want, but they must still bond this 
ground rod in with the other electrical grounding, making the 
additional ground rod somewhat superfluous (other that it contributes 
to the overall efficiency of the entire grounding system).

My suggestion is that it wouldn't hurt to look around and see if you 
can tell how your cable is grounded before it enters the building, 
particularly if your cable service is overhead.  It's just one more 
thing that can help protect you and your equipment.

--Joe


-----Original Message-----
From:	scottb at pixel-group.com [SMTP:scottb at pixel-group.com]
Sent:	Tuesday, December 18, 2001 10:54 AM
To:	ale at ale.org
Subject:	[ale] Off the Wall

I am trying to protect my new tv and pc from lightning over the coax what is
the best way othere then unpluging to prevent the strikes from coming over
the cable line  

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