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Re: [OM] XP networking - it was the @$%^* router after all

Subject: Re: [OM] XP networking - it was the @$%^* router after all
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Wed, 3 Aug 2011 09:47:24 -0500
Ah, granite. How lovely.

Your electrician is absolutely correct. The well casing is great for most
grounding applications and still should be tied in. But building a proper
groundfield (which can be expensive if installed commercially for a large
current load facility like a telephone switching office), creates a relative
ground instead of an absolute ground. It is possible that you are literally
miles away from an absolute ground connection. In eastern Kentucky, for
example, there are areas which are dozen or more miles away from an absolute
ground. The power-lines in those areas include a return ground. Our
telephone networks in those areas are even more convoluted.
The well casing would provide a decent grounding for standard 60Hz powergrid
return path, but won't address lightning because a hit two miles away can
still affect you as it travels through the water table before finding an
area to neutralize the discharge.

So, depending on local code (some areas don't allow for double-bonding of
grounds), what I would do is build a ground-field. This would incorporate an
array of copper spikes driven somewhere around eight feet into the ground
and connected with large-guage braided copper.This is then brought back
inside (usually to your basement to the large sheet of plywood which all
your panels and interfaces are), and bonded/bolted to a large copper buss
bar. Each utility entrance is then grounded to this buss bar with its own
bolt. (Do not use any form of solder at the buss bar). Again, depending on
local code, you will also run a large-guage copper wire to the well casing.
These grounding wires MUST conform to minimum radius bends. The key to
survival here, is that EVERY wire, conduit, pipe or even fiber (fios cables
almost always have a metallic wire in them, btw), that comes into the house,
entrance either near the grounding buss bar, or have a substantial grounding
wire going to the buss.

Another thing to do, if your code allows for it, is to build a halo ground
in the attic. A halo ground can be internal or external if you don't have to
access inside the roof. I've seen halo grounds built under eaves. This is
also bonded to the grounding buss. If properly done, the halo ground will
protect all internal wiring within the building.

Sewer systems and septic system also need proper entrance (exit?) grounding.
In fact, this is a real problem in some areas because they can be a
tremendous source of back-fed lightning. "Yup, it came right up out of the
toilet!" Septic systems can also be a source of RFI coming back into a
building. "Honey, why is it that the local radio station plays in the
shower?" Basically, anything that comes in from the outside gets grounded to
the buss bar. No exceptions.

So, what does all this mean in the real world?

Lightning will enter a house via one utility service and exit via another.
Cable TV is very common. The lightning comes in on that cable, blows through
the television and exits the power grid. You always want a shortest path
solution for the lightning. And that shortest path should always be to the
buss bar.

Yet, there is another issue with lightning. That's static buildup. The
general rule of thumb is that if you can drain off static fast enough,
you'll never get hit. This is true with airplanes and radio masts. In fact,
with tall television/radio towers, there are static wicking arrays that can
be installed at various points on the tower. These are so successful that
when the tower does get hit, it's at the midpoint on the tower between
arrays.

The problem you are encountering is that the water-table grounding (through
water pipes or well casings) is that it is lousy for static grounding. A
ground-field, however, is excellent for static drainage. One provides an
absolute ground, the other provides a relative ground. For static grounding,
you need a relative ground.

AG
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