This gets down to what your inspector considers subject to physical damage. In Maryland, seeing RX stapled to running boards open on a block wall or seeing SE fastened to an exterior wall was just how it was done. In SW Florida they want it in pipe if it is not concealed. I have never seen RX surface mounted where it is readily accessible or SE used on exterior walls. They used to even require a sleeve on RX behind drywall if it was on furring strips. Now they will allow a "stacker" to space it 1.25" away horizontally from the furring strip but I am not a fan. It is still within 1.25" from the surface of the drywall and susceptible to a nail strike.

Greg Fretwell