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To: "'Charles Coldwell'" <>, "'Stephen Davis'" <>
From: "Gary Schafer" <>
Date: Tue, 4 Jan 2011 16:34:06 -0500
List-post: <">>
One way to fix this problem (having power come in on one side of the house
and satellite coax on the other side) is to install a power protection
outlet box at the end of the house where the TV and satellite are located.
This box or panel would have power line protectors in it and also a coax
protector in it or bonded to the box. A heavy ground lead would tie into a
ground system immediately outside. You can then plug the power lead into any
convenient outlet to power the outlet box with the protectors in it. Power
all equipment that is connected to the satellite system ONLY from that
protected box. 
You have created a mini single point ground system for the TV and satellite.

This can be done for any other systems in the house like your ham station.
Power line protectors do not need to be only at the service entrance. If the
service entrance is a long way away from where other lines come in to the
house this is a good option. It keeps all lines at the same potential
without long interconnecting leads. Again just be sure that ALL lines
feeding the equipment go through this box/panel.

Polyphaser used to make a box like this. Maybe still do?

Gary  K4FMX

> I recently bought a house that has the main electrical panel at the
> front (grounded to a water pipe) and had (past tense) both OTA and
> satellite TV coax coming from the antenna/dish through the back of the
> house.  The 75 ohm coax runs were grounded with a rod driven into the
> back of the house, and there was a long long #6 or #4 THHN wire
> running from that grounding block at the back of the house to the
> panel at the front.
> What's wrong with this picture?  Well, that long run of #6 or #4 has
> an inductance.  That inductance becomes an impedance at high
> frequencies during a lightning strike, which means that the voltage
> potential at the panel ground and the coaxial ground could differ as
> K4FMX said, "Sometimes by many thousands of volts!"
> That voltage difference between the coaxial ground and the panel
> ground will appear across the electronics that are connected to both
> grounds: i.e. the satellite receiver and television that are both
> plugged into the wall and connected to the antennas.  Voom!
> Once again, as K4FMX said, "This means that ALL equipment and lines
> connected to that ground system must rise together to avoid damage."
> That is why, IMHO, just running a long THHN wire between grounds is
> not enough to prevent equipment damage.  Yes, it is a short circuit at
> DC, but don't let that fool you.  Lightning is an impulse with all
> kinds of high frequency components!
> Chip
> --
> Charles M. Coldwell, W1CMC
> "Turn on, log in, tune out"
> Belmont, Massachusetts, New England (FN42jj)
> GPG ID:  852E052F
> GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F
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