> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Gary Schafer
> Sent: Thursday, October 13, 2005 10:40 PM
> To: BIRCHWAY@aol.com
> Cc: amps@contesting.com
> Subject: Re: [Amps] Dedicated 220AC Wiring for Amps..
>
>
>
>
>
> _____
>
> From: BIRCHWAY@aol.com [mailto:BIRCHWAY@aol.com]
> Sent: Thursday, October 13, 2005 9:44 PM
> To: garyschafer@comcast.net
> Subject: Re: [Amps] Dedicated 220AC Wiring for Amps..
>
>
>
> I spent 30 years as a broadcast engineer. Power companies and broadcasters
> are paranoid about lightning hits and go to great lengths to minimize
> them.
>
>
The power company is only concerned about their own equipment. They care
little about the customer's equipment.
>
>
> We had a 700 foot tower and
>
> the sections are prepainted on the ground and then erected, so they are
> effectively insulated
>
> from each other with paint. Each section had a heavy copper wire to the
> next
> one.
>
>
It is standard practice to put a strap around each tower leg joint even if
there is no paint in the joint. Joints have a high resistance compared to
the rest of the tower. Even though that joint resistance may be only a
tenth
of an ohm or less. It can have a substantial voltage drop with the high
current of lightning.
>
>
> there was a 25 square foot copper screen buried at the tower base and
> strapped to the tower.
>
>
A buried screen does little for lightning dissipation. Length is needed.
>
>
> 2 inch copper strap was buried out to each of the three guy wire bases and
> strapped. 2 inch copper strap was incorporated into the concrete of the
> building foundation and tied to strap going out to the tower. All as a
> counterpoise for lightning.
>
>
Many ground rods and a single point ground for all equipment are also
needed
for a good lightning ground.
>
>
> We still had trouble initially, as a hit would take out things like tape
> recorder motors, florescent ballasts, i.e. things with a high power
> factor.
> the final solution was to buy some old trolley wire from a junk yard which
> was rectangular heavy ribbon. This was buried about two blocks to the city
> water system and tied in.
>
>
Two blocks distance is much too long to be effective for lightning. If the
water system was tied in or not it probably would have made no difference.
>
>
> We never had any more problems with the two 25 kw amps going out either.
> Lightning will look for the " softest " ground, which could be in your
> yard
> or further down the power line. if you walk down your power line and look
> up
> at the pole, you will see that there is a jumper from the neutral down to
> a
> ground rod at each pole. If a hit happens to get into the pole pig
>
> and can't get to ground, it can boil the oil and blow the housing apart.
> The
> power company engineers are the real pros when it comes to lightning. My 2
> cents, sorry about the long post....
>
>
Lightning will go to the lowest inductance ground path.
73
Gary K4FMX
>
>
> Bob...W0PQX since 1945....
>
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