Expose Romex on the backside of Main Panel..Question?

[David Nasser]

Does the the romex need to protected from the backside
of the Main Panel to the House....This is in the garage.

[Robert Meier]

The oldest version of the NEC that I have, 1987, states that exposed NM "cable shall closely follow the surface of the building finish or be on running boards" and must be protected when subject to physical damage. Subject to physical damage is a subjective determination made by the inspector or AHJ. Since this wiring looks rather old I would guess that it was determined to be OK when installed.