Conduit necessary for exterior run?
I‚Äôm helping a friend re-wire the 2nd floor of their 70 year old house (has the old BX w/ crumbling cloth insulation). For various reasons the best way to get wire to the second floor is by running wire out the basement wall, up the exterior wall to then into the attic through the eave. My intention is run the exterior wire in schedule 40 PVC conduit properly anchored, etc. The electrician who upgraded the service panel, however, claims I can do without the PVC and simply use exterior rated wire (either the underground or UV rated). All wire on the exterior will be above grade. The electrician pointed to the wiring for the A/C unit and air handler as not being in conduit. I‚Äôm still unsure. Common and safety sense tells me it should be in conduit but I cannot find an applicable in my NEC for dummies book. Any code experts out there? (Sorry for the long post.)