Fulgurites

[Volta]

When cloud to ground lightning hits sandy areas, it will sometimes create fulgurites- glass structures formed from the rapid expansion from heating, forcing a usually vertical space in the sand, the silica melting, and then cooling and becoming solid.

If a ground rod for an electrical system carries current from a lightning hit (remote from the soil, higher on a structure), is it generally considered that:

1. It has done its job, but now likely has a higher resistance to the surrounding earth and should be supplemented with another,
2. It has done its job, and can still be considered good for future high voltages,
3. Was never that good, never will be, and they still help,
4. It is time to buy a ground rod tester, or
5. Something else I haven't yet considered?

This question is in regards to the soil in central Ohio, a little clay, not sandy, but is pertinent everywhere, I suppose. What are your thoughts?

Brett

 

[zog]

When cloud to ground lightning hits sandy areas, it will sometimes create fulgurites- glass structures formed from the rapid expansion from heating, forcing a usually vertical space in the sand, the silica melting, and then cooling and becoming solid.

If a ground rod for an electrical system carries current from a lightning hit (remote from the soil, higher on a structure), is it generally considered that:

1. It has done its job, but now likely has a higher resistance to the surrounding earth and should be supplemented with another,
2. It has done its job, and can still be considered good for future high voltages,
3. Was never that good, never will be, and they still help,
4. It is time to buy a ground rod tester, or
5. Something else I haven't yet considered?

This question is in regards to the soil in central Ohio, a little clay, not sandy, but is pertinent everywhere, I suppose. What are your thoughts?

Brett

Could be all of the above, only way to know is have it tested. I have a small fulgurite collection that I have dug out after a bad test.

 

[LarryFine]

If a ground rod for an electrical system carries current from a lightning hit (remote from the soil, higher on a structure), is it generally considered that:

1. It has done its job, but now likely has a higher resistance to the surrounding earth and should be supplemented with another,

How would one know when a lightning strike has occured? They're not always witnessed.

 

[brian john]

Zog pretty well summed it up......

 

[Volta]

How would one know when a lightning strike has occured? They're not always witnessed.

Very true. In this instance though, the fire fighters doused the resulting second floor flames.
That's a good point though, if there is any loss of conductivity from use, maybe rods' connections to soil should be checked every so often . . .
Thanks.

 

[bphgravity]

There would likely be other evidence of a direct lightning strike that has terminated into the earth via the service ground rod(s). The most common would be dead or dying vegatation / grass at and around the ground rod and perhaps extending out a few feet in jagged radials.

This could be an indication of changes in soil conditions. Unless you see other damage to the service or grounding system as a result of a direct strike, I would not worry about it one second and leave it as be. Normal climate conditions and rain patterns will likely restore the normal or average earth resistance of the electrode.

 

[zog]

Very true. In this instance though, the fire fighters doused the resulting second floor flames.
That's a good point though, if there is any loss of conductivity from use, maybe rods' connections to soil should be checked every so often . . .
Thanks.

Cant find my 70B right now (Where did I leave that?) but I think it says every 3 years (Brian?)

 

[LarryFine]

In this instance though, the fire fighters doused the resulting second floor flames.

In my best Seinfeld voice: "Then why have a lightning rod?"

 

[stormywyo]

Lightning strikes objects of opportunity based on height. As long as the attractor rods are higher then the building, it will continue to strike the rods. The condition of the connections and conductor should be assessed if there is a known lightning strike. The resistance of the ground rods is of little importance since the lightning will follow the down lead to the ground level if it is installed properly...

 

[charlietuna]

All the lightning strike damage that i've witnessed has always been different in it's method of entry and exit--almost like it has "no set pattern"--guess thats why they call it "UNPREDICTABLE"?

 

[stormywyo]

Yup--lightning protection is our best attempt at controlling it. Ben Franklin invented it so I am surprised at some of the posts--kind of predated the telegraph...

 

[charlietuna]

NASA is or has installed three 500 foot towers around the new launch site at Cape Canaveral to protect our next generation of space rockets--the last 100 foot section is made of fiber glass???????????????????

 

[stormywyo]

They could make it from wood--it really doesn't matter.. Fiber glass would be a good media for building up a positive charge. As this is what triggers the down strike...