2/12/2007- QOD - Electrical

[Paul W. Abernathy]

Here...check out this site to better explain lightning systems
http://wvlightning.com/protection.shtml

Note: If you want a PERSONAL opinion....I would require the lightning systems GE to be minium 15' from all house electrodes and not connected to the system......but thats me......the NEC requires they are connected together because in their vision the ENTIRE system acts better for the lightning system & that it will reduce voltage potentials and possible flash arcs because of metal object proximity......personally I am not a THEORY lightning expert...my knowledge comes from learning theories from experts in that field and coveying them .

Here is why they would like the GES and LPS to be bonded together.....guess I can agree with this

Where a lightning protection system is installed, it must be bonded to the building or structure grounding electrode system as per 250.106. In addition, the grounding electrode for the lightning protection system cannot be used for the building or structure grounding electrode [250.60].
Note: The bonding of the lightning protection system to the buildings or structures electrical system, via the grounding electrode system, is intended to prevent lightning "side flash" or arcing between metal parts, which can result in a fire by minimizing the difference of potential between the lightning protection system and the electrical system.
See NFPA 780, Standard for the Installation of Lightning Protection Systems for additional details on grounding and bonding requirements for lightning protection.

[jkogel]

Thanks, Paul. Now let me see if I got the ground rod question figured out. Any stray charge leaking out of say a power tool w/ 3-prong cord would travel back to the service panel via the grounded conductor. There, it can flow down to the ground rod OR take the neutral path back to the source. So it follows the path of least R, which is the neutral.
OK, by that logic, it should be alright to jumper the ground plug right to the neutral in the outlet box, since it's going to flow that way anyway?

[Paul W. Abernathy]

No the voltage takes ALL paths of resistance....it is proportinally greater on the least resistive path but in fact it takes all paths.

You are confusing logic....you are saying....Paul since the Grounding Electrode Conductor is attached in the panel anyway....and the Grounded conductor is the path back...why need the EGC.....is that not what you are beating around the BUSH to really ask?

The earth is a weak..very weak conductor at best........are you going against conventional logic as to why the fault current would travel back on the grounded conductor to clear a fault versus on the earth....this can be done simply via OHMS law.

The EGC lets say in that " POWER" took will take any voltage from Line to Ground and remove it via a low impedance path back to the source....allowing the OCPD to fullfill its function......the earth could not provide this function...do the math on a 25 OHM ground rod...

120V into 25 OHMS = 4.8A...do you think this would clear the fault?

The connection to ground helps to give zero potential but not to clear any faults.....the ground rod in itselfs function is for lightning, Transiant voltage and surge voltage.