It has been suggested by some of my colleagues that IEEE 1584 equations can be used to calculate the incident energy resulting from a faulted MV cable in a manhole. Am I correct in my understanding that the equations in IEEE 1584 are only applicable to a fault between conductors having an air gap? If this is correct, I don't see how the equations are applicable to finding the incident energy of a faulted medium voltage cable that won't have any air gap between phases or to the grounded shield. The only way I can trick the software to making this calculation is to insert a bus with an air gap at the manhole location, but this does not realistically model a faulted cable or splice and I don't have any confidence in the results. Does anyone have any experience or guidance with this situation?

I agree with you, not to mention you are in a manhole and the dynamics of the whole space are different.