I am wanting to add a permanent attic ladder to create storage space in a big attic. There is already exposed wiring in a few places in the attic. If I add a permanent ladder, does that then mean that according to code that all attic wires now need to be protected? Some of the cable would be covered by 3/4" plywood for flooring, but other cable is hanging above in the rafter braces. If I add this ladder, what are some different options to protect this hanging cable so it meets code? Or is that really necessary if it's not in the main part of the attic for storage that will have the plywood flooring?
I have never had an AHJ confront me about exposed romex in an attic with or without a permanent ladder. One quick note though, if you are laying down plywood Make sure there are no electrical cables laying across the joist where they may be pinched and shorted. Notch the joist and use nail plates or reroute the cables.
If you install a permanent ladder, the attic is now considered "accessible" and per the code section below the cables have to be protected. However, note that you're only required to protect the cables running across the faces of rafters or studding, not cables running between the rafters or studding. If, as you say, the cables are up between the rafters, on the bracing, they are not affected by this rule.
If you need to route cable through the joists, you can notch or bore holes in the joist. The illustration below shows that you can notch the OUTER thirds of the joist a maximum of one sixth the width deep and one third the width long. Wires in notches will require a nail plate for protection. Bored holes can be up to 1/3 the width of the joist, but must be 2" from the edge. With 2x6's, the actual width is 5-1/2" so there is room to spare for holes in the 3/4" to 1" range centered or nearly centered through the joist.
Where Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8 m (6 ft) of the nearest edge of the scuttle hole or attic entrance.
Note - 320.23 is a rule pertaining to AC cable, not NM such as Romex brand; but the rule for NM, 334.23, references 320.23.