Dspark,
Welcome to the group!!
What Don is getting at in his message is to have the Utility company's secondary point of ground bonding to the grounded conductor be the one and only point where the grounded conductor is bonded to the earth.
The equipment ground bonding conductor that would run parallel with the service feeders is bonded to the X0 terminal [center tap on 1 phase 3 wire, or common for 3 phase 4 wire, or 1 phase for 3 phase 3 wire], which is also the grounding point and output of the grounded conductor. From there, the EGC would be the conductor which would be bonded to each service / grounding electrode system per customer. Kind of like how a separately derived system would be grounded - except there's not multiple Grounding Electrode Systems and services. Same consept, though.
This method would create one grounding point, but not have the problem of carrying L-N currents [unless some joker hooks up a load to the ground bonded equipment or conductor].
As for Lightning, each discharge will have such a large electrostatic field built up in a somewhat circular fashion around the central point where the main discharge will occur. This field will be bringing in and pushing away charges from all around - at times upto 2 miles. During the discharge event, the stroke leaders that did not make a solid connection will still be active throughout the duration of pulses and build up / drain of the potential energy between the cloud mass and the earth at point of contact - plus field areas. The main stroke[s] are the few stroke leaders which make solid contact, then create the brightest / largest plasmas and have the largest current flows [1"-1.5" diameter area of charge flow].
All throughout the discharge field area, there's thousands of branch discharges - some barely visiable, most not. They flow on any possible conduction paths around.
These are the ones that range 1KA to 5KA, whereas the main stroke would have a level of 50KA or higher.
The main stroke when it [and the branches] begins to conduct, would have the highest voltage [pressure] between the cloud and earth. After the Plasma is created, the voltage drops to very low values [from 250KV per meter to less than 1KV per meter], while the current level rises rapidly [from 500 amps to 50KA].
Anyhow, eliminating numerous ground bonding points that are common to overhead power lines and to underground piping, would assist in lowering TVSS and Lightning potentials.
Having the equipment ground bonding conductor grounded at the transformer and at each service would drive the EGC to ground level at that point of service.
Feel free to throw flames!!!
I'm just mentioning the Lightning stuff for FYI and discussion reasons only. Feel free to debate any part that seems odd.
Scott SET
