According to the panel specification label I can install up to a 2 1/2 inch hub and conduit. I did not plan on running conduit across the attic but 4 Conductor jacketed cable. I was inquiring the correct type of cable to use. The conduit would only be to protect the cable until it passed through the soffit panel. If I ran a 100 Amp Circuit I would terminate the cable at the back porch in a small 100 Amp rain tight panel and install the 50 Amp breaker there and wire the inlet off that panel with #6 gauge conductors.