Some years ago I saw a study that proved that rigid aluminum conduit was the most effective equipment grounding conductor through impedance measurement, skin effect and fault current carrying ability testing.
I'm pretty certain it also proved GRC, IMC and even EMT - when properly installed - to all be superior to a "skinny" copper conductor sized per then 250.95, now 250.122 for "typical" pipe and wire sizes for branch circuits and feeders. I don't recall now if EMT data included different fitting types or if they just used steel compression or steel set-screw or die-cast etc.
I may be wrong about the various steel pipes vs. copper wire but am certain that rigid aluminum was the best. I think the study went so far as to mention any loose couplings in steel raceways being welded together under a fault but I also may be wrong about that.
Is anyone familiar with such a study and if so know where to find it on the net?
I'm pretty certain it also proved GRC, IMC and even EMT - when properly installed - to all be superior to a "skinny" copper conductor sized per then 250.95, now 250.122 for "typical" pipe and wire sizes for branch circuits and feeders. I don't recall now if EMT data included different fitting types or if they just used steel compression or steel set-screw or die-cast etc.
I may be wrong about the various steel pipes vs. copper wire but am certain that rigid aluminum was the best. I think the study went so far as to mention any loose couplings in steel raceways being welded together under a fault but I also may be wrong about that.
Is anyone familiar with such a study and if so know where to find it on the net?
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