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Old October 25th 04, 05:20 PM
Richard Harrison
 
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Jack Painter wrote:
"Here is where you are mixing apples and oranges=A0because ground loops
and lightning protection are not related."

A ground loop is a potentially detrimental condition due to two or more
points in an elewctrical system that are nominally at ground potential
being connected by a conducting path.

A ground loop may provide a common impedance which couples energy
between two or more circuits. Strength of the energy in the electrical
circuits is immaterial in a current loop so long as nothing breaks down.
Response to the excitation is the same.

A lightning strike is a huge noise injection. Techniques for noise
reduction and testing are
also applicable to lightning suppression and may be tested with weak
noise signals. I know from personal experience.

It is desirable to avoid common impedances which can couple lightning
from one circuit to another, as a "ground loop" may.

Ground connections for protected equipments can be made with individual
wires between each of the devices and a common ground point to avoid
ground loops. This is not always practical.

It is usually practical to enclose devices inside a conductive
enclosure, then to low-pass filter and surge protect every wire which
penetrates the enclosure.

A screened room can serve as both noise and lightning protection, for
example.

Best regards, Richard Harrison, KB5WZI