The system in our potash mines are resistance/grounding type.Since potash is not a conductor grouding is done through cable connected to the switchgear box on the surface. When we use the software to calculate the incident energy,do we need to consider the impedance of the grounding cable also for each equipment?

You won't experience single phase faults because of the NGR. The shaft feeders have a ground in them but you're looking for phase to phase faults in an arc flash event so I'm not sure why you would consider the grounding conductor?

Also the software's cable library should auto populate the cable information when you're buiding your model.