Do you place an arc flash warning label on the back of equipment if it can be accessed from the rear?

Yes, anywhere there is access to voltage.

Working Distance

I believe that rear acessible gear should be labeled on the front and rear, my question is should the working distance be calculated at a lower distance threshold (18") in lieu of 24" for switchboard / switchgear or 36" for medium voltage switchgear. I am not an electrician by any strech, however in recent converstions with some local electricians I asked. "do you ever have to work on switchgear (600 volts and less) hot", answewer from the majority (four out of six) in some applicaitons where the bus cannot be de-energized then yes we will work on the rear of a piece of switchborad or switchgear hot". I have to believe that when working in the back of the gear that the working distances are much closer than the 24" or 36" in the standard for the front of the gear creating for a greater hazard. Curious on everyones thoughts.

It would seem appropriate to use "cable" as the equipment class for cable termination compartments. This changes the typical gap to 13 mm and the typical working distance to 455 mm (see IEEE 1584 Tables 2 and 3).

We label the equipment in one location visible at the front. Any qualified worker knows what an arc flash label looks like and will seek this info. I do not want the liability of guessing each place that voltage might be accessed.