[TowerTalk] Re: Wind pressure

[K7LXC@aol.com]

Howdy, TowerTalkians --

      Gary, K7FR, an electrical engineer for a utility company sent me the 
following:

In a message dated 04/13/2000 4:11:14 PM Pacific Daylight Time, 
GNieborsky@kec.com writes:

> In the National Electric Safety Code there is a good discussion of wind
>  pressure.  26 lbs/sq.ft. at 100mph is what we design to for transmission
>  lines.  This applies to wires as well as structures.  There are factors for
>  strength for wood and steel plus all the flat plate/round member numbers.
>  Interestingly enough these factors are for strcuture taller than 65' !  
They
>  get derated for shorter structures through loading area considerations.
>  Most of the NW is medium loading for distribution lines and most
>  transmission lines.  Almost all utilities apply the local experience factor
>  though.  Here at Kootenai we design to heavy loading because of ice and
>  wind.  Transmission lines all go heavy.  Heavy loading also includes 1" ice
>  (winter) and 100 mph wind and 212 degree conductor temp (summer).  Needless
>  to say some poles get really herky!  Believe it or not, 100 mph and 212
>  conductor temp has more loading than 1" of ice!

      Tnx, Gary!

Cheers,   Steve   K7LXC

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