[wxqc] Grounding of anenometer mast

[Sam Drinkard]

On Tue, 2006-03-14 at 13:14 -0500, Dennis Maier wrote:

> As soon as it's safe to climb up on my second story garage roof I intend to
> extend the height of my anemometer from about 7' to maybe 15' or more above
> the roof.
> 
> At the present time the Davis Vantage Pro anemometer is connected to their
> Wireless Anemometer Transmitter mounted on the mast just above the tripod.
> Also mounted on the same mast a couple feet below the anemometer is a large
> TV antenna used to pickup On-Air HDTV. The TV antenna coax is routed into
> the garage through the roof eaves vent down to the ground floor and into a
> metal patch panel enclosure and grounding block then into the house. The
> enclosure and a coax grounding block are grounded with #4 copper wire
> through the wall outside to a ground rod. I did it this way to preserve the
> appearance (no unsightly wires) of the newly vinyl sided house and garage.
> At this time the mast is not grounded.
> 
> Was this, routing the wires inside the building before the ground block, an
> unsafe decision from a lightning standpoint?
> 
> Because of occasional missed data packets from the Wireless Anemometer
> Transmitter when I extend the mast I will probably hardwire the anemometer
> to the Davis ISS and do away with the Wireless Transmitter. So that will be
> additional wires running from the mast to inside the home.
> 
> I live on the waters edge of Saginaw Bay off Lake Huron in the Thumb of
> Michigan. A few years ago lightning struck the electrical wires entering my
> home at the utility pole, so I know it likes my area.
> 
> What are forum members thoughts about grounding the mast? I worry that
> grounding the mast will just attract more lightning strikes.
> 
> 
> Dennis Maier
> CW4869
> 
> _______________________________________________


I'll "ditto" the comments from others, but the best information (and
code compliance) will come from the NEC and NFPA.  They are your best
bet, but if you live in a lightning prone area, there is really little
you can do except *try* to keep the strike OUT of the house.  If my
memory serves me correctly, I believe any grounding line should be
mounted on the outside of a structure and if possible, on standoff's in
as straight a run as is practical, terminating in a well low resistance
rod a minimum of 8' deep.  I'm going from memory so my wording might not
be per the NEC & NFPA but you get the idea.  One way to tell if you are
classed as a lightning prone area is to contact your homeowners
insurance company and ask them.  Those companies keep records of all
areas of the country, and I know, at one time I could not buy renters
insurance for a house I used to live in at Boiling Spring Lakes, NC as
it was rated both a lightning and fire hazard area.

Sam
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