The year 2020 provided me with the unique opportunity and the time to produce a series of videos on topics that you told me were of interest to you. I recorded them from my house, and livestreamed them over the course of several months. There were a lot of you that might not have been able to tune in, and others who did, but would enjoy the chance to see them again. We'll be sending them out monthly in a newsletter series. Enjoy and feel free to share!
 All grounding electrode conductors terminate to the service [250.24(A)(1)], at each building were supplied by a feeder [250.32(A)], and at a separately derived system [250.30(A)(1)]. Why do some grounding electrode conductors have to sized larger than others?
Where a grounding electrode conductor is required, Table 250.66 is used to size the grounding electrode conductor [250.66]. If you have a electrical system failure that results in a ground-fault, fault current would take all available paths back to the source including the grounding electrode conductor.
For example, if energized parts of the electrical system come in contact with the structural steel, then the structural steel will act as the effective ground fault current path back to the source and the GEC will be a part of that path. Another example is a scenario where you lose the equipment grounding conductor connection and electrical equipment fails causing a fault. In this case, the building structural steel will serve as the effective ground fault current path [250.4(A)(4) and 250.104(C)] back to the source so that the overcurrent device can open and clear the fault.
If you find yourself wondering why you have to use such a large conductor to building steel when you only need max 6 AWG to a ground rod and 4 AWG to a concrete-encased electrode, join Mike on this video to unveil the method behind the madness.
Click here or on the image to watch the video [54min:52sec].
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