Protection by Lightning Rod(s)

[croy]

On the top of Mt. Whitney, California, there is a stone building, about 12 ft. x 25 ft., festooned with no less than

9 lightning rods. All the rods appear to be connected together, and there are over 9 wires from the system to earth. The building has a thick wood floor.

I've read that two people have been killed, and something like 15 injured (some seriously) by lightning while taking shelter in this building during a lightning storm. Presently, there are warning signs, warning against taking shelter in the building during a storm.

How can such a seemingly well-protected building be such a death-trap?

[philo]

If someone was any where near one of the grounding wires, they'd get one hell of an inductive shock. Think of it as a 1:1 transformer.

Though it might be inefficient and lossy, considering that a lightning can be 100,000,000 volts there would be plenty left to fry someone.

[NotMe]

The key word is 'seemingly'.

The physics of installation/maintance of lightning protection is complex. A simple thing as right angle bends while they may look professional can render lightning protection worthless.

[philo]

Plenty of Google hits

here is one

[Mayayana]

| How can such a seemingly well-protected building be such a | death-trap? |

First, do we know it's actually true? You've read? Where? When?

Second, we don't know about the lightning protection job. And how are the cables grounded? They won't get much ground in rock, but that may be all that's available.

I'm not sure there's any value in speculating about something of which we have neither expertise nor details.

[gfretwell]

Were they killed before they installed the lightning protection? Maybe they were leaning against the walls instead of being in the center of the room.

I have a lightning rod on my garage and was in the driveway (with another guy) once when it was hit. It was certainly exciting but we all came out OK. We did feel the force of the hit, it was like a sudden explosive shock wave going by but no real "electrical" sensation.

[hubops]

.. that's my guess - step potential / touch potential .. ... with all the other variables - wet storm conditions - .. no safety gear ; etc Dunno. John T.

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[Paintedcow]

It's probably the tallest point on that mountain, and thats why it get struck. Anything that's tall is most likely to get struck. TV towers are regular targets because of their height.

Maybe the State or County should build some sort of underground "bunker", so people have a place to go during storms.

[Mayayana]

| > First, do we know it's actually true? You've | > read? Where? When? | > | | Plenty of Google hits | | here is one | |

|

From 25 years ago. And I don't see anything in that article about lightning protection.

[philo]

Looks like you are right

[croy]

Thanks for that link. It would sure be interesting to know if the 9 lightening rods presently seen on the hut were there when the people were injured. I would suspect that they were, since the original decision to build the hut was based on the death of a researcher because of a lightning strike.

It's also interesting about the stove-pipe, but I would think the rods, with much better grounding (maybe not *good* grounding, but certainly better that the stove and stove-pipe), would be a more likely target for lightening, but my knowledge in the area is very slim.

The real key to the story would be to know the presence of rods, and the quality of the grounding, when the folks were killed/injured.

[croy]

That's the $64 question.

One of the injured said he was leaning against the wall.

Have you inspected the rod and ground wire since the strike? I've always been curious to know what happens to a well-designed and built lightening rod system when it gets hit.

If a LR system is typically damaged by a hit, then I'd suspect the rods on the Whitney hut would have an average life-span of about 3 days.

[gfretwell]

Not a mark. The system did it's job. In fact the weather station on the same pole survived too. I just had to reboot the PC it was connected to.