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Joined: Oct 2000
Posts: 2,749
Can someone tell us why this "dirt" was turned into a solid mass after a lightning strike?

[Linked Image]

Joe Tedesco, NEC Consultant
Joined: Nov 2000
Posts: 2,148
The current flow through the resistance between the grounding electrode and the earth created enough heat to turn the earth into a form of glass. This has also been found where the lightning has struck the earth directly without a grounding electrode.

Joined: Apr 2002
Posts: 2,527
Silica, a major component of "dirt," was heated to liquefaction and cooled. Fallen overhead conductors can cause a similar condition. One term for the fused material is fulgurite.

Joined: Apr 2002
Posts: 197
Gwz Offline

Do you suppose it is radio-active ?


The glass theroy is good.

Joined: Sep 2001
Posts: 806
Should be no more radioactive than it was before the lightning hit...

Joined: Oct 2001
Posts: 597
Cool example, Joe.

Following on Bjarney's comment about fallen overhead conductors. . .I once came upon a PoCo line crew repairing a 13.8 kV 3Ø line after one phase had dropped to the sand and gravel along the edge of the alley. The line laid on the ground and "burned" and hopped around and shortened itself leaving a dashed line of fulgurite holes in the sand and gravel. One was long and large enough to stick my hand down into. It was still warm.

Think of this. . .If the ground resistance in the arc is one Ohm, and only 100 amps flows, and the voltage to ground is 8,000 volts, the area in the arc has 0.8 MegaWatts dumped into it! [Linked Image] [Linked Image]

Al Hildenbrand
Joined: Apr 2002
Posts: 2,527
Conductor movement with distribution line-to-ground contacts can be unbelievably energetic—appearing almost "cartoon-like".

Never forget that distribution- and transmission-fault voltage gradients in the form of deadly or incapacitating touch {hand-to-foot} and step {foot-to-foot} voltages can be phenomenal, and far exceed that generally expected of the insulating capability of most rubber-soled boots.

Joined: Oct 2000
Posts: 2,721
Broom Pusher and
To add on with everyone's great examples;

The Fulgerite (sp???) shown, is the typical result of a succession of current flowing through the same contact point, and performed the same action on the Silica as would be done in a normal Manufacturing process to make Glass.
Simply stated, the high TRUE POWER transfer - in continuous duration - created a high heat in the soil, which fused the Silica crystalline Molecules in the soil, and resulted in the Fulgerite structure.

Most discharge points will result in this formation - as long as they remain continuous in the same point.

When Trees or Wood Poles are involved, things may take one of two results:

[*] High Current peaks may simply shatter them - without setting fire,

[*] Succession of current peaks with continuous current will set them on fire.

Similar may be said to happen with conductors - High current short time charges passed through a rubber covered conductor can eliminate the wire, but leave the rubber covering unharmed.
Successive peaks with constant current will barbeque both the conductor and the rubber insulation.

Hollow, or flat conductors, are often crushed by high Lightning currents - owing to both the heating and magnetic effects of the discharge(s).

Many, Many, many-many-many coulombs flowing under an extremely high EMF: results = high transfer of True Power.

Just as impressive as the Fulgerites (to me) are:
* The EXTREMELY LARGE and successive Plasma created during a solid discharge,
* How the Plasma "Pumps" the surrounding air into a HIGH POWER Thunder sound (the successive increase and decrease in the Plasma's size results in the generation of the powerful thunder sound...and as Tim Taylor would say: "Oh, Ohhh, huuh Huuaah!!!"),
* How many pulsations occur during a discharge,
* How many "Aux." discharge points are involved,
* And how the entire event is constructed (includes the discharging from above the Stratosphere into the cloud, then the "Drain" from Stratosphere clouds into the Earth). Within this includes the very large Electrostatic field present in the "Zone", and how it pushes / pulls / moves charges from or to distant locations during the entire event process!

So, does this show my interest in the phenomena, or what! ???


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: Jul 2003
Posts: 394
At home, sitting on a shelf, I have something called a "sand dollar". Florida is the lightning capitol of the US, if not the world, and has lots of nice, sandy beaches. When one strikes the other, it often fuses the sand into a fairly flat, circular mass. The ones they collect and sell to the tourists are 2 to 6 or 8 inches around and have various holes near the edges. When you think about melting sand almost instantly, it helps to put the power on lightning into perspective.

Joined: Oct 2000
Posts: 2,749

I wondered about the "solid pile" of dirt for some time, and now have some very useful information that will help many to understand the phenomenon!

Thanks to all who have replied so far!

[Linked Image]

Joe Tedesco, NEC Consultant
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