Use of terms "ground" or variations of that base word or "earth" do not help. Then we use conductors that are "grounded" or "earthed" at some point as a "return path" for fault current, which is an accurate statement - but easily misunderstood.
I think it boils down that at one point in time the CMP literally thought soil did everything for an electrical system. Truth is outside of indirect lightening it does nothing. And a direct lightning hit will make no difference.
Earth does not soaking up electrons, does not provide equal potential, does not stabilize or anything else. Statements like "earthing" via water pipe or water pipe electrode are misleading. We do not bond water lines so much because part of the pipe is in contact with soil, we bond for reasons far more important: clearing a fault and maintaining equal potential.
In fact the entire goal is to create a faraday cage within the structure, not gain access to everything that just so happens to touch soil like myths lead us to believe. Soil electrodes vs faraday cage are two very different concepts and the a latter is what protects life and property. People should view every building as sitting on a giant rubber mat and then consider earthing electrodes in the picture after everything is bonded within the structure.
What is misunderstood is that the conductor whose function is fault clearing only isn't there so much to connect to earth, as it is there to return fault current to the source - it just happens to be a conductor that is normally at "ground potential".
Exactly :thumbsup:
And I would further argue that the EGC isn't so much at ground potential but rather at the same potential as the faraday cage in the building. Further, during a fault the voltage drop across the EGC will produce a voltage potential between the faulting chassis other bonded objects like water pipes which will usually be half the normal line to neutral voltage.
The only time the statement holds some truth is in a TT earthing system. TT earthing is used exclusively in some parts of the world like France. And yes the earth is used for fault clearing, and earth wire may be a correct term for an EGC, however the soil is not absorbing electrons. Rather it is just conducting them back to the transformer. TT earthing is just using the soil an EGC, nothing more than that. And because soil is so poor at conducting electricity in order for TT earthing to work you need a low level deferential RCD breaker.
Lightning is not necessarily trying to get back to earth though many believe this is what is happening in almost all lightning events. It is simply opposite charges in two different places and once the voltage is high enough for electrons to jump the gap or the two areas finally move close enough for jumping the gap we have discharge. Lightning does sometimes jump from ground to cloud instead of from cloud to ground. Lightning also jumps from cloud to cloud instead of to ground.
Very true. Its not the earth itself, but difference of potential between cloud to ground. Many people will say "drive a ground rod for lighting protection" Well, truth is if you want lightning protection don't look at the NEC. Look at the NFPA 780. You would be surprised what lightening protection really involves.