As I was reading your post that was exactly what was going through my mind.
That is what - a garage on the other side of the door? An option would be to open a small hole from the garage-side in the adjacent bay just big enough for 2 hands to get in. Run conduit down that bay and put in a sweeping 90 to terminate into the side of the bottom panel. No drywall repair on the finished side and conduit to run more wire if/when needed. You may want to run the wires outside the conduit to leave it open for new runs.
It is a garage on the other side. While the conduit is certainly a good idea, I already have (2) 2-gang boxes down there (on the laundry room side, in the adjacent panel). One is the power coming in for this work (on it's own separate breaker), along with (6) Cat5E cables that will be patched to the lower panel providing connectivity between panel equipment and rack equipment. The other is (2) of the power inlet receptacles (
http://www.amazon.co.../ref=pd_cp_hi_2) one for each panel; which will enable me to put either or both panels on a UPS.
Since the panels will only be about 6" apart, I dont think it would be that difficult to run additional cabling between the later if needed; I figured I would also run a couple stands of nylon pull cords just for that reason.
Those panels are kinda meant to fill the whole cavity and not have room behind them.. I've always just passed the wires between the cabinets as needed (right now I have a 50" on top of a 20").
Another option is to just not put it flush, and to make it look nice use some trim around the edges to frame it in.
Thanks for the confirmation - I figured someone else had done it, I just wanted to make sure there was really no issues with doing so. With regard to the trim, you can see that is what was done with the existing alarm panel. The thing is that panel is only about 12" wide, so when the larger Leviton panels are installed they will almost touch the cabinets; I think the cover panel may actually touch them (yet to be seen). Here is what it looks like right now:
Note that the 14/2 cable (pictured) in the lower cavity is a new run for the upper Leviton panel; currently there is no power in the existing alarm panel, as the transformer is in another part of the home.
Also, following the current UPS thread in the security forum - I plan to leave the alarm connected as it is now; with the alarm panel transformer connected in another location and utilizing the standard alarm battery for backup. The UPS providing power to the inlets and thus power in the enclosures will be for the other devices, such as the Axis video encoder, CCTV cameras, cable modem, router, etc.