IMHO the problem here is a focus on true statements which are effectively false, and which reinforce a dangerous falsehood. Thus the pushback.
False is if it has no basis in the written standards which are based from actual experience by engineers using instrumentation to verify the laws.
The dangerous falsehood is 'ground rods will effectively dissipate excess electricity and make things safe.'
What make you say this falsehood. Grounding rods if not effectively grounded is not effective but if it is effectively grounded it helps dissipate. IEEE STD 142 Chapter 1 and Chapter 2
Many people thing that grounding electrodes are a magical cure-all for a host of problems, and will thus misuse ground rods.
Again the requirement is effectively grounded and bonded.
It is a dangerous false myth that if you connect an enclosure to a ground rod then that enclosure could not shock someone.
It helps with UNGROUNDED AND HIGH RESISTANCE GROUNDED if effectively grounded. Check IEEE Standard 142. Please show your basis. Check voltage to ground of current carrying conductor connected to ground.
For the low voltage ( <600V systems that most electricians on this site work with), a standard ground rod will not pass enough current to trip a breaker, and would only slightly decrease the touch potential at the fault.
Operation of OCPD is only one of the objective of EGC. Another objective is to reduce touch potential of a bonded grounding rod connected to earth.
EGC in ungrounded and HRG will not trip the OCPD. EGC for ungrounded and HRG will only operate ground detector but will not trip the OCPD. Clearly EGC that is grounded or connected to earth reduces the touch potential to prevent electrocution. OCPD in solidly grounded need to operate because of arc flash and arc blast caused by single line to ground fault.
Let's take a specific example, a metal lamp post with a line to enclosure fault. The source is a grounded wye system, and the lamp post base is insulated from ground. The post is not bonded to an EGC. A line to pole fault will energize the pole to full line voltage relative to 'remote earth' and present a severe shock hazard.
If the rod that is connected to earth is bonded and effectively grounded the person touching the pole even if the OCPD will not operate is protected. KEY IS EFFECTIVELY GROUNDED
Now we add a ground rod to the lamp post. With normal ground rod impedance you might see 1 to 10A of current. wo p
BONDING the ground rod to the EGC will have the connection to earth effectively grounded. The EGC will now be in parallel to the earth. The equivalent impedance of two parallel conductors EGC and EARTH is always lower than the lower impedance in parallel. Lower impedance means more effective in operating the OCPD.
The impedance of the circuit supplying the fault and the ground rod form a voltage divider which _slightly_ reduces the voltage (to remote earth) of the lamp post and significantly raises the voltage of the soil surrounding the ground rod
It will not raise the voltage if the connection to earth is effectively grounded. You have to bond the ground rod to the EGC
. Touch potential is somewhat reduced, mainly because a person standing on the soil now has their feet at elevated potential and the potential difference between the two contact points is reduced.
Sorry. If the rod is effectively grounded the resistance of the soil will be reduced because part ot the current will flow MORE to the EGC because it has lower impedance and current in the EARTH will be low. KIRCHHOF'S current law.
There is no practical safety benefit to adding this ground rod.
There is benefit specially if the OCPD did not operate. You can see the benefit in UNGROUNDED SYSTEM AND HRG SYSTEM. Single line to ground fault in UNGROUNDED AND HRG SYSTEM will not trip the OCPD. AGAIN, the ground rod should be effectively grounded
Now let's say we add a second ground rod. This second ground rod reduces the ground electrode impedance. The changed voltage divider means the voltage of the lamp post goes down slightly, and the increased extent of the grounding electrode spreads out the voltage gradient in the soil. This reduces the touch potential slightly, and thus makes the situation slightly safer, but does not in any practical way make the situation safe.
Using KIRCHOFFS CURRENT LAW. Effectively grounded system will have less step potential as the majority of the current will flow to the EGC and very small current will flow to the ground.
Mr. Ocampo is _correct_ that adding better grounding reduces the danger of shock from exposed metal. We are pushing back because in a practical sense this reduction in hazard is negligible for our purposes.
It will not only help but it is the prupose of connection to ground. If OCPD malfunction the effectively grounded rod will prevent electrocution.
But the physics is correct, and in different circumstances additional grounding does improve safety. Consider higher impedance sources and more extensive grounding.
KEY IS EFFECTIVELY GROUNDED
Mr. Ocampo brings up the example of a grounding grid at a substation. In this case the source impedance is much higher (either from the transmission line or from lightning, and the ground electrode system is very extensive). This grounding could reasonably be expected to significantly reduce touch and step potentials, and will likely trip the protective relaying.
Regardless if the PROTECTIVE RELAY OPERATES OR NOT, person inside the substation should be protected
Exact same physics applies in both cases.
And if you were to install a huge grounding grid at your lamppost it would reduce touch potential and trip the breaker. Or you could simply install the EGC
EGC bonded to the ground rod will do the trick
During fault cleaning time the circuit conductor-fault-EGC impedances form a voltage divider, and energize the pole creating a touch potential. Adding a ground rod will reduce this touch potential. Determining if this reduction in touch potential has any practical safety benefit is an engineering exercise.
Principles are in IEEE 80
