[TowerTalk] lightning rods, splineballs, and 1 irons

[Jim Jarvis]

Recently, I consulted with the cap'n of a large charter 
sailing vessel, who had posted here concerning lightning
protection.  He was losing masthead instrument pods due
to lightning hits.  

I recommended a lightning rod which was above all of the
topside stuff.  Much as rods are used on bcdst towers to
protect the topside beacon lamps.  

They have their uses...but the sharp point tends to provide
a locus for corona to take place, and in turn lower the 
impedance of the potential strike path.  So...they 
encourage lightning, if not attract it.

On a building, lightning rods with robust ground paths will
tend to protect chimneys and roofs, and those within, by 
providing low impedance paths to ground, and discouraging
streamers.  

Will spline balls do anything more, or better?  Well, if 
they're more efficient producers of corona...they will more
likely lower the strike path impedance, and encourage lightning
hits, rather than the opposite.  

Therefore, if you use them...following good grounding practices
becomes more important than ever.  (In my humble, if only partly
informed, opinion.)  

As for me, I'm sticking with a plastic owl and a 1 iron on the
tower top.  Not only are birds offended, God has better sense than
to play golf.   

n2ea
jimjarvis at ieee.org