Adventures in Linguistics: He is X nor Y

I had a curious experience in semantics class today.  We were covering the scope of negation, and the professor had presented us with three sentences:

(1) Pat isn't a plumber and isn't an architect.

(2) Pat is not a plumber or an architect.

(3) Pat is neither a plumber nor an architect.

Part of what we were discussing was the fact that all three of these sentences mean the same thing  (that is, the sentence is true only if Pat does not belong to either of these professions), but it seems that (1) and (2) derive that meaning differently, and we were working on which of those sets of rules apply to (3).

I won't bore people with the technical details, but along the discussion, one of my classmates brought up an example of their own:

(4) Pat is neither a plumber or an architect.

Which was grammatical to her, though I find it slightly questionable.  This encouraged me to bring up an example that I had been mulling over in my head for about 10 minutes:

(5) Pat is a plumber nor an architect.

Though I thought that (5) was good and means the same as (3), apparently no other native English speaker in the class agreed with me that (5) was grammatical at all.  One person thought it may have to do with me being from "the South" -- which still amuses me, since I never did consider the part of West Virginia I come from particularly Southern (I suppose it looks very different from Wisconsin).  In any case, it did lead to a short discussion of what could possibly be going on with my dialect of English to cause this construction.

It's funny how these things pop up.  I've had a moment like this before, when the double-modal might could was brought up in syntax class (that one I know is common in Appalachia and the South, but not up here), and I'm sure these things will happen again.