bphgravity
Senior Member
- Location
- Florida
I'd like to offer a thought experiment on grounding requirements in order to hopefully understand a little better what we are hoping to accomplish with an electrode system.
I have a stucture with a concrete encased electrode, metal water pipe, and structural steel. For whatever reason, two ground rods are also installed. Next door is another structure with no concrete encased electrode, no metal water pipe and no structural steel. It only has two driven rods.
At the first structure, someone accidently comes along and cuts the conductors going to all the electrodes except the ground rods. So effectively, the first building is now basically indentical to the second one. The question. IS my first building any less safe now or less protected from transients and surges?
If yes, I will conclude that it is imperative to require all present electrodes to be used when designing the electrdoe system. If no, I conclude that one or more of the electrodes could be permitted to be used if desired, however only one would be absolutely required.
Second question. Lets say the first building has approx. 11A flowing on the electrode system before the conductors were cut off to the extra electrodes. After, the current drops to .75A. Would this not be considered objectionable current and therefore the removal of the other electrodes may be acceptable?
The point that I am trying to get across, is that if a structure with only grounds rods satisfies the minimum requirement of the code, why would the code require more and more electrodes for another structure with slighty different conditions? This sounds like design to me.
I have a stucture with a concrete encased electrode, metal water pipe, and structural steel. For whatever reason, two ground rods are also installed. Next door is another structure with no concrete encased electrode, no metal water pipe and no structural steel. It only has two driven rods.
At the first structure, someone accidently comes along and cuts the conductors going to all the electrodes except the ground rods. So effectively, the first building is now basically indentical to the second one. The question. IS my first building any less safe now or less protected from transients and surges?
If yes, I will conclude that it is imperative to require all present electrodes to be used when designing the electrdoe system. If no, I conclude that one or more of the electrodes could be permitted to be used if desired, however only one would be absolutely required.
Second question. Lets say the first building has approx. 11A flowing on the electrode system before the conductors were cut off to the extra electrodes. After, the current drops to .75A. Would this not be considered objectionable current and therefore the removal of the other electrodes may be acceptable?
The point that I am trying to get across, is that if a structure with only grounds rods satisfies the minimum requirement of the code, why would the code require more and more electrodes for another structure with slighty different conditions? This sounds like design to me.
