how would you know if they failed unless you happened to notice a loose GEC flopping in the breeze.
Doesn’t have to be flopping in the breeze, just a high resistance connection from a loose connection. That rule applies to all grounding electrode conductors, not just to a ground rod. That’s why code requires it to be non-reversible because you will not know it failed until it’s too late.
what would constitute "too late"? since as a practical matter it does not really do much, even if it failed what would be the consequence? Unlike where an EGC failed there well could be a very serious consequence.
If it’s that unimportant, the why have a grounding electrode at all?
an excellent question.
how would a GEC provide any protection if a MV conductor happened to touch a service conductor?
If an MV line fell on the messenger of a service drop, the premise electrode would help the fault clear.
exactly how would that happen.
A tree blows over in a storm and, say, a 7.2KV line falls on a service drop and makes contact with the messenger. Then messenger is probably grounded at the pole side too, but lets say its not and all we have is rods at the building which is 50 ohms. Even at say 50 ohms, that line should trip out. There is a chance it wont too, depending on a variety of factors. This is likely the only valid reason given in 250.4(A)(1).
the messenger supported insulated conductors surround the bare messenger so how would the 7200 V line ever touch the messenger cable?
The two insulated wires are wrapped around the bare wire. Not surrounding it. Happens more often than not, although I’m not sure the rod has any effect.
I have a hard time seeing how the insulated conductors would keep the MV line form touching the messenger. I suppose it is possible if everything was positioned perfectly but IMO its very unlikely.
POCO service triplex is not insulated, it’s covered. A few years ago, a 12.5 kv line fell across a service drop, blew the service panel (outside) off the wall
So it didn't do any good to have the ground rod.
I don't think we can conclude anything from such limited information. It is possible the ground rod helped clear that fault and it would have taken longer to clear or done more damage, who knows. All I am saying is it is plausible to come up with a scenario where ground rods help with contact with higher voltage lines.
If I earned a nickel for every time I got called out.
