Yes, but it would not be an ungrounded system. The connection to a grounding electrode is incidental. The purpose of the EGC is to provide a path for ground fault current to flow that is not dependent on current flowing through earth and the grounding electrode. Ground current will flow through the EGC whether or not it is connected to ground. Ground current does not have to flow through the earth.
That's right.
If there is a ground fault on the incoming 4160V, then if the 4160V source is remote, a portion of the fault current will return through the earth. Current flowing through the earth will raise the voltage of the grid with respect to the remote source ground point. The ground grid makes the substation surface voltage fairly uniform and close to the voltage of the grid, reducing the voltage that would exist between a person's feet (step-voltage) and between his feet and hand while touching a grounded structure or equipment (touch-voltage).
Okay, so I don't have to respond.
The current has to get back to its source, not the earth. The will carry some of the current back to the source if it is a grounded system, but it will rarely carry enough to open the OCPD. It also does not do a good job of providing an equal potential. In areas where you need equal potential, like substations and the like, there is a bonding grid that provides the equal potential.
The physical determination of a grounded system is the fact that one of the circuit conductors of a grounded system is connected to the grounding electrode(s) via a grounding electrode conductor. The equipment grounding conductors connect the metal parts of the equipment to the system grounded conductor via the main bonding jumper and to the earth via the grounding electrode conductor. The fault clearing work is done by the equipment grounding conductor and not by the grounding electrode conductor.
If there is no system conductor connected to a grounding electrode then the system is not a grounded system.
If we are talking about system of 600 volts or less, then it is not likely that the earth will carry enough current to open the OCPD. If you are talking about medium or high voltage systems, then it is likely that the earth will flow enough current to open the OCPD. It is ohms law at work...the higher the voltage the more current that will flow though a given resistance.
There is no electrical or safety reason to provide a grounding electrode at that cabinet. The only thing that will remove the hazard is to clear the fault by tripping the OCPD...the only thing that will do this is an effective EGC.OK as I am researching this more I am begining to understand this subject a little better. Grouding is a difficult subject to grasp
Let me give another example:
Lets say I have a metal enclosed cabinet in the field with electrical equipment insisde and a 480V power supply to this cabinet. Lets say that this cabinet is grounded by taking a ground conductor from the frame of the cabinet to a ground rod in the earth.
Now if there is a L-G fault on this cabinet I now understand that because the earth is such a high resistance, the grounded connection to earth will not clear this fault. Lets suppose for some reason there is not an EGC to this cabinet an therefore the fault does not clear.
So without this fault clearing even though the cabinet is grounded through earth there will still be a dangerous voltage on the cabinet surface which will be 277V or close to it depeding on the resistance of the fault point and little current flowing through earth.
So if someone were now to walk up and touch this cabinet lets say from standing 3ft away would they be exposed to this 277V and be shocked. If the answer is yes then what is the point of even having a grounded earth connection at this cabinet.
I understand that this cabinet should have an EGC and this would hopefully clear the fault and eliminate this voltage on the cabinet. But why ground this cabinet to earth if this ground connection will not do anything to eliminate the dangerous voltage potential? Am I understanding this right?