Lightning Arrestor in Action

[SunEagle]

The best lightning avoidance device I have seen is the spike on a very tall tower which creates a "cone" of protection almost like an invisible Faraday cage.

The other type is used by POCO's where they string the ground wire above the HV wires of a transmission line. The ground wire is supposed to be hit by lightning before any of the phase wires below it gets struck. Still with the power of lightning there is no way to totally protect something from being hit or damaged.

[Sunking]

Yep as a Power Protection Engineer, I keep trying to tell folks that (sigh). They can help with nearby strikes and minor utility faults if properly sized, located, and installed Problem is most consumer units are Junk, and not even many sparkies (Electricians & Installers) know how to properly install them. Even if you get it right, will not do squat on a direct hit.

So why are they sold? . Because there is a Market for them and people buy them.

FWIW the best consumer units you lease from the POCO. They are what is called Meter Collar SPD. They come out and inspect your Service Disconnect (meter box) to make sure you have the proper Ground Electrode and code compliant wiring inside your Main Breaker Panel. Once you satisfy their requirements are met, they unplug your meter, Plug in the SPD Collar, then plug your meter into the SPD Collar. They charge you a monthly fee of a few bucks which is actually supplemental insurance in the event you take a direct strike with damages. It will cover what your HO insurance does not pay like deductibles and depreciation. They are simple 3-Mode SPD and each mode is rated 40 to 100 Kva for 800 usec per mode depending on the size of your service.

[bcroe]

Lightning arrestors have limited capability, but can help in lower energy situations. Bruce Roe

[citabria]

One of our Towns Booster Station took a direct hit from lightning on the weatherhead power drop. Attached are pictures I took for the insurance claim:

The lightning travelled through the bottom bearings of one electric motor and turned the bearing into slag. The only thing prevented the building from burning was the local rancher happened to be nearby to put out the fire, and the walls of the booster station are cinder blocks.

The main circuit breaker was exploded through the NEMA box bending the exterior weather door.

So, the lightning arrestor doesn't really do much other than become a projectile, and a potential fire source.


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