There is no doubt appliances located in closets, attic spaces, & attics make it extremely difficult for compliance with the NEC requirement for working & dedicated equipment space.

That being said, the installer has several options to come into compliance. If space is not provided for an actual disconnecting means, the a "unit swtich" can be installed. If there are no provisions for a "unit switch", a breaker lock-out device can be installed.

I will admit I have approved disconnecting means located with one or more working space dimensions NOT in full compliance, but where I was readily & easily able to approach, examine, operate, and inspect the equipment without resorting to acrobatics or other unsafe practices.

But those are exceptions to the rule, not the rule...

Several good thought provoking opinions given. Odd how a string can take a life of it's own. Going from 110.26 working space for a transformer to equipment located in closets, attics, and such. How maybe it shouldn't really apply to receptacles and switches, to judgement calls, to absolutely applied in all cases. Would someone actually try to verify the torque of transformer lugs while it was still energized? If you have a transformer that is being supplied correctly yet the output is incorrect, ie single phase rather than three phase, would you really have to remove the cover to realize that there was a bad connection or an open winding? Going back to the original question, and from your opinions, the working clearance as outlined in 110.26 would be required.
Again some good opinions. Thanks.