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What good is a GROUND ROD?

5K views 60 replies 21 participants last post by  bobelectric 
#1 ·
Why do we insert a ground rod into the earth when a direct lightning strike would surely burn a #6 GEC to smitherines?
 
#7 ·
Actually, testing has shown that a ground rod's maximum dissipation capacity can be safely handled with a #6 copper conductor. This is why the Code does not require any conductor larger than a #6 when connected to made electrodes. Using anything larger is a waste of resources. :blink:
 
#8 · (Edited)
Lightning is a not-very-well understood phenom, but I think Sparky's take is pretty good science.

That said, a ground rod "locks" a local system at the potential of local "ground." I don't believe it is for lightning, although it certainly serves to help "bleed" the voltages between earth and sky so they don't reach "arc-over" levels.

Discovery Channel has an amazing show on about lightning. It is part of the "Raging Planet" series. http://dsc.discovery.com/search/results.html?query=lightning&search.x=23&search.y=9&search=search

That said, I am amazed more homes aren't hit by lightning since one might think the EGC system throughout a house would make an attractive target, but they aren't, so I guess something is working right.

At any rate, I think of the GEC and rod as a path for electrons to ebb and flow so the EGC system and local earth are generally at the same potential.
 
#9 ·
Peresonally, I believe the rod is virtually worthless. Of course if lightning wants in, there is almost nothing one can do for the "BIG ONE" to stop it. Rods probably help on small strikes to some degree . The CEE is my MO whenever possible. I installed 2 rods on a job around here and I got 98 ohms. I disconnected it and did another 3 point test on my CEE and I got 13 ohms. I wish they would enforce the CEE rule but as it is not many are doing it.
 
#10 ·
How effective a driven electrode is dependent on the soil conditions at the time of the strike, distance from the panel, how the GEC is installed (tight bends negate the the effectiveness of the GEC), magnitude and duration of the stroke, where the lightning hit the structure, and a few other factors that are a secrete of Mother Nature:blink:

I have installed some very elaborate grounding systems, 100's of 10" rods, #2 AWG tinned in a circular pattern with long legs going out in multiple directions and the seemed to help until that big mother lode hit one day during storm and everything in that facility plus 5 adjoining residences and business lost all electronics.
 
#14 · (Edited)
THIS IS A QUOTE FROM WACO: I don't believe it is for lightning, although it certainly serves to help "bleed" the voltages between earth and sky so they don't reach "arc-over" levels.




Yes, the grounding rod is for lighting!!!:donatello:holding a ground rod!!!:laughing:
 
#25 ·
Worked a job similar to this today: previous "electricians" pulled the water pipe ground from the water pipe entrance to the outside disco, some 40 feet away from the panel, which was only 5 feet away from the water pipe entrance. WTF? They also bonded the ground and N together at the sub panel, thus making my day even longer.
 
#36 ·
The original question here was what good is a ground rod? Well the answer is it used to keep me so buff doing all that hammerin, which chicks dig...
Then some wise acre back around 1980 or so tried using his concrete buster for the job, realized it was way easier, and then that spread like wildfire.... Without the daily workout, beer soon got the better of things, and the potbellies started growing on all the electricians across the land. Thats why women now go get short hair cuts and date each other, they don't like budwiser guts. It all started with jackhammers........


I put combo meter mains outside, rod outside (existing building, otherwise its an uffer for new work), and hit the closest h20 pipe coming out of the ground. I don't give a rat's ass about any 5 foot requirement cause I am not required by the nec to make my water connections withing 5 foot of anything so long as they are outside. The guys who write the code understand the concept. Many who read the code mess it all up. Its only required for interior connections.
 
#37 ·
The original question here was what good is a ground rod? Well the answer is it used to keep me so buff doing all that hammerin, which chicks dig...
Then some wise acre back around 1980 or so tried using his concrete buster for the job, realized it was way easier, and then that spread like wildfire.... Without the daily workout, beer soon got the better of things, and the potbellies started growing on all the electricians across the land. Thats why women now go get short hair cuts and date each other, they don't like budwiser guts. It all started with jackhammers........


I put combo meter mains outside, rod outside (existing building, otherwise its an uffer for new work), and hit the closest h20 pipe coming out of the ground. I don't give a rat's ass about any 5 foot requirement cause I am not required by the nec to make my water connections withing 5 foot of anything so long as they are outside. The guys who write the code understand the concept. Many who read the code mess it all up. Its only required for interior connections.
Excuse me!!!:shutup:
 
#46 · (Edited)
What good is a ground rod? At the service not much IMO thats why we have to drive 2 of them now. And if you check you may still need 2 or 3 more. But if you look at the big picture. You are creating a ground grid for the utility company.
 
#47 ·
Ground Rods

What good is a ground rod? At the service not much IMO thats why we have to drive 2 of them now and if you check you may still 2 or 3 more. But if you look at the big picture. You are creating a ground grid for the utility company.
I am not fully understanding what you are saying...but if you are saying that one ground rod may not be enough, I am in agreement. The NATIONAL ELECTRIC CODE BOOK is the BARE minimum that you HAVE to do. Is that good enough for YOUR house...and your family?
 
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