I know NEC 250.122 takes you straight to a table that has had equipment grounds sized as long as I've been an engineer, but I recently came across a situation where I wanted to plot a conductor damage curve and a circuit breaker TCC curve. The conductor, an equipment ground, is #8 CU THHN and the circuit breaker is a 100A branch circuit overcurrent protective device (standard fixed trip MCCB). Now consider what 250.4 (A) (5) says (this is the key to this discussion) and a situation where a phase to ground fault has occurred at the equipment served by the 100A breaker and the #8 EG is in the return path. The attached TCC plot suggests to me that the #8 is not "...capable of safely carrying the maximum ground-fault current likely to be imposed on it..." in compliance with 250.4 (A) (5). Any thoughts?