Vintage Windmill and Wind Generator Forum

I worked for a friend that was in the wind electric business in the 1930's and he inspected a big Jacobs that had been struck. He said a hole was blown through the end-bell cover that was close to the diameter of the generator! (About 12")

It is a common misconception that concrete would isolate but that is not the case. Concrete because of moisture wicking and moisture holding capabilities better than earth provides a good ground. Do a google search on Ufer ground systems. In CO, the NEC has required residential house grounding to a footing rebar for the past 15 years, no ground rods are used.

Lightning likes to take the shortest path to the best ground. All equipment grounds need to attach to one common grounding point, otherwise multiple ground points cause a difference of potential. Often well pumps are hit because there is not good direct path grounding before it. Proper grounding of equipment is the best lightning protection.

Metal towered windmills that have good tight bolted overlaps do not need to be grounded. I would guess Smax pic of lightning damage was caused from an overlap that didnt provide a good path to ground. Wood towered metal head windmills would merit being grounded.

Ron Stauffer
Montrose CO