I think I see what Roger is asking. If I have a big flat concrete pad a couple inches above ground, and a house sitting on it, I presume it is "at grade". If the pad extends 20 feet beyond the house in all directions, standing on the pad next to the house would probably still be "at grade level".
Now let's raise the house. At what point do we say it is no longer at grade level? 6 inches? 2 feet? 5 feet? 12 feet?
210.52(E) uses the term "at grade level" in 2 ways. One is to select which units of a "two-family dwelling" must have these outside outlets. It seems the intent is that a 2nd floor apartment of a 2 unit building do not need this. But this still begs the question just how high is still "at grade level". I think much of this will hinge on the definition of "level". Think about it in terms of "floor levels" of a house.
If a dwelling that is 2 feet about the actual dirt level (not uncommon) is still considered "at grade level" for this purpose, then "at grade level" can mean whatever height to qualify. What I'm saying here is that since "at grade level" is used to qualify the unit to have these outside receptacles ... and "at grade level" is specified as where they must be accessible, then this must be implying that the same height can be used. So if the outlet is accessible from the porch at the same height as the house floor itself that is considered "at grade level", then the porch at the same level is suitable for "at grade level" access.
So there are 2 aspects to this question. One just how high does "at grade level" really mean (is there a definition somewhere?). The other is does "at grade level" mean the same thing in both places it is used in 210.52(E)? I can't see how one phrase can be expected to have 2 different meanings in the same paragraph.
So it seems to me that if a porch is at the same level as a house where the entry floor is considered "at grade level", then the porch is also "at grade level" ... whatever that is.
Disclaimer: I am not an electrician/EC. I just hire them sometimes to do electrical work in data centers I may be designing or managing. I'm also digging into these issues for a house design I may be building in the future.
