[ale] Off the Wall

[Joe Steele]

Geoffrey wrote:

> When I first got cable in Cherokee county (about 10 years ago), they
> attached a wire, probably about 8 gauge, stripped about 6 inches off the
> end and stuck it in the ground.  When I happened to notice it, I called
> them and they told me there were doing more then they were required as
> they were not regulated...

A pitiful excuse,  but not surprising.  

Of course, they are full of B.S.  Cities and counties have codes, 
regulations, and franchise agreements which specifically govern cable 
TV operations.  I would bet that those codes almost always require 
adherence to the NEC in one way or another.  They certainly do in 
Roswell where I live.

>
> I'd expect that if your cable is hit by lightening, regardless of the
> ground you've got, you're going to lose something.
>

No argument there.  Assured protection from a direct lightning hit is 
probably impossible.  The real issue is surge protection, and proper 
grounding can help in that regard (as can surge protectors).

Current surges can result from switching operations on power systems.  
Surges can also be caused by induced voltages from lightning which 
doesn't hit power and CATV systems directly, but which is merely in 
the vicinity.  If the grounded conductors and parts of the power and 
CATV systems are not bonded by a low-resistance path, surges 
traveling on one of the systems can raise the potential difference 
between the two systems to many thousands of volts which can lead to 
arcing between them -- not a good thing when your expensive large 
screen HDTV is connected to the both of them.  

By bonding the power system ground together with the CATV (as 
required by the NEC), the likelihood that the potential difference 
between the two systems will reach dangerous levels whenever a 
current surge enters a building is significantly reduced.

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