If you turn to Section 250.122 in your NEC, you find information that has assisted electricians sizing equipment grounding conductors (EGC) for longer than most electricians have even been twisting wire.If you were on the job in 1968, you would have turned to Table 250.95 in your NEC for this information instead of Table 250.122, but the information was essentially the same.In 1968 you also would have found that an ungrounded (hot) branch circuit conductor protected by a 6000-amp overcurrent device required no less than a 1200 kcmil aluminum equipment grounding conductor… assuming you were using an aluminum equipment grounding conductor. That information remained unchanged for 50 years. But as the saying goes, “All good things must come to an end.”
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