[Towertalk] Grounding mast to tower

[K7LXC@aol.com]

In a message dated 4/2/02 7:10:11 AM Pacific Standard Time, 
k1ky@bellsouth.net writes:

> I have measured the resistance between Thrust Bearings/Rotors and their 
> mounting
>  points. It isn't a pretty picture, usually something like 10-30 ohms.  

    Interesting. Was the measurement on the bench or on the tower with 
vertical weight on it? I suspect that the weight would compress the bearing 
more and decrease the resistance slightly. 

>  This 
> could explain why the rotor is usually one of the first to go as a result 
of a 
> strike or nearby hit.
>  
    Is that right? Since it's attached to the mast, a direct strike would 
make sense. The rotator is chock full of places for the strike to arc as 
well, unlike the simpler tower and antennas.

>  I take a #4 flexible conductor and tie it to the mast and then the tower 
> below the  rotor mount. No problems to far.

    This may be more psychological than real help. If it's stranded, the 
strands will oxidize over time which increases their resistance. Any bends in 
the jumper will discourage the transient from following that path as well. 
Maybe you've been lucky.

Cheers,
Steve    K7LXC
TOWER TECH