On Thu, 29 Jul 2004 09:39:57 -0400, Pete Smith wrote:
>Illustrative of the difficulties of doing the single-point ground thing
>properly with an old house, our telephone and cable TV connections are 180
>degrees around the house from the AC power entrance, grounded to a rod at
>that point
I have a similar problem in my 110 year old Chicago house -- telco on the
northeast
side of the house, power on the southeast.
Last I looked, code says that all grounds must be bonded together. It is NOT
legal
(nor is it safe) to have things tied to separate rods (or ground electrodes)
without
bonding those electrodes together. Ideally those bonds need to be as short as
possible and outside the building, but those two requirements can often be
conflicting. If I ran the bond outside my building, it would need to be at
least 100 ft
long and require a lot of trenching. Inside the building ( basement) adjacent
to the
grounding blocks, it could be as short as about 30 ft. At 1 MHz (the
approximate
peak of lightning energy per IEEE) there's a big difference in the inductive
reactance. What's a mother to do?
Jim Brown K9YC
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