[TowerTalk] Tower grounding

[Tom Rauch]

> I have a Megger. We used it for insulation checks on motors and cable to
> change them out before a catastrophic failure. Is there a source for using
> the Megger for earth ground checks, web or book?

Megger?

If you are reading ground resistances on a megger you are in big 
trouble!

An AC ohm meter is required, but it needs to be a fairly low scale 
meter.

Virtually all low-frequency AC readings have very limited value for 
lightning because the primary energy is in the hundreds of kilohertz 
range, not at DC or 60 Hz.

The safest approach is to install a well designed ground system, 
and not worry about trying to measure something that isn't easy to 
measure and doesn't mean much anyway even if you do manage to 
measure "something".

The NAB (National Assoc of Broadcasters) Handbook has an entire 
chapter on lightning. It is an excellent unbiased discussion, since 
they are not interested in selling anything.


73, Tom W8JI
w8ji@contesting.com

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