Thanks for the additional replies!
Bjarney;
Scott — I get bogged down on the term "reactive coupling" as it applies to utility power and distribution transformers. Should it be "leakage reactance"?
Sorry about the "Clear as Mud" descriptions used!
![[Linked Image]](https://www.electrical-contractor.net/ubb/eek.gif)
I was referring to Capacitive Coupling, Inductive Coupling and Leakage Reactances / Line Charging Reactances (Relative Permittivity) per the Coefficient of Coupling technobabble.
This data will be very, very, very-very-very difficult for readers to grasp, if that person does not understand the basics.
Even more difficult if this is the first time the reader has heard of such stuff!
What I need to do is make things much easier to understand, for those readers - while keeping a proper level for the more advanced reader.
Is this possible with a topic such as the one referenced here?
nesparky;
I would question your 8 amp with the ground rod witin 5 ft of the water pipe in wet soil.
This example scenario is to describe how distance and soil characteristics effect the conductive properties of an Earth-Ground type circuit.
In most normal conditions, the rod would need to be driven within 18" of the water pipe, to achieve a current of 8 amps flowing under a pressure of 120 Volts.
This example scenario is figured to be "Isolated" from all bonding for the rods, with the water pipe bonded to the power system in some direct method (such as N-G bonding at a service). The only conductive path between the rods and the water pipe is the Earth (dirt).
I saw this type of thing happen by mistake once.
A worker got in a hurry to terminate wire in a hot panel and shorted a #4 ground wire to a 20 amp breaker.
The # 6 bare melted but no breaker tripped.
An HVAC guy told me that he saw the bare #6 turn red, then melt.
time was less than 30 sec.
( the existing panel was federal pacific)
If this Fault resulted in a fused #6 cu conductor, then the fault level must have exceeded 300 amps for 30 seconds, or 500 amps for 10 seconds (don't have current density data at hand, just shootin' from the hip!).
That level of fault would exceed the typical "No-Trip" characteristics of FPE MCCBs, but also might exceed most other MCCBs too!
Hence, no trip of the device would occur.
Likely the conductor which faulted to the 20A Breaker, was solidly bonded to the equipment + system, or was connected to solidly bonded water lines, gas lines, etc.
If this happened, and the conductor was only connected to driven rods, it would be the best ground rod application ever!
The Resistance for the rod's part of the GES, would be less than 1 Ohm! Somewhere in the area of 0.5 Ohm would be likely here!
You may have a ground loop there with most of the current not traveling to the source, thus the breaker may not see enough currrent to trip.
Just a question based on a scary experience.
This is very true! The GES does not have the ability to conduct a sufficient level of current needed to trip an OCPD - even one of 10 Amp rating.
By its self (no bonding to the AC system involved), the GES will not clear a Ground Fault - due to the high Impedance between it and the Power Source.
Proper and solid bonding techniques are important to follow, to avoid the above situations.
The currents in a closed circuit will flow from the Power Supply (source), thru one conduction path (wire), thru a given contact point / load (for instance, a metallic enclosure), thru another conduction path (wire), and finally back to the Power Supply (source).
What flows out will eventually return again.
If a heavy flow originates from a given point - like an OCPD, the device will respond accordingly.
If flow is below rated capacity for Maximum load current, the device remains closed (unless it sucks!).
If flow exceeds the device's rated capacity for an extended period of time, then a trip function will open the device and flow will cease (again, unless it sucks!).
Thanks to everyone for the replies!
Scott35
