A neighboring jurisdiction has a large amish base and he is starting to see electrical circuits being placed in the homes. . . would the house be required to meet the provisions of NEC for outlet spacing, GFCI, required circuits, etc.
Interesting question. Here's my opinion.
As you describe it, I realize these are existing dwellings that were not constructed originally with a Premises Wiring (System) - from Article 100 Definitions. And, per your description, the new wiring is most likely being added on a load by load basis for specific use, as opposed to General Lighting Circuits or Small Appliance Circuits.
I think of the obligation that I, as an electrician, must meet to be
Code compliant when I go to an older home and install a 125 Volt 20 Amp Laundry Circuit. Say that this dwelling was built in the first half of the 1900s, to the electrical code in effect during construction, but that it never had a designated Laundry Circuit. Now, today, I am adding a Laundry Circuit using the requirements of today's
Code for the Laundry Circuit install, that is, the receptacle will be TR, may be GFI protected, will be a grounding-type receptacle, will be on a 20 Amp circuit, etc.
But, the install of the Laundry Circuit in an existing dwelling, built originally without a Laundry Circuit, doesn't, by the
National Electrical Code, invoke any additional electrical requirements beyond the Laundry Circuit, such as Laundry Area Lighting, etc.
My point, . . . Unless there is Local Ordinance that establishes a minimum electrical system configuration for EXISTING buildings, the
NEC is a new construction only document. When new wiring is added to an existing dwelling that previously had NO Premises Wiring (System), the new wiring must meet only the requirements that apply directly to it.
So, in the case of outlet spacing, if I install a circuit to supply a computer at a desk location, it is for a specific load / use. If I wire a room for General Lighting, then that one room would follow the applicable passages in the
Code pertaining to it. The remainder of the dwelling remains outside of the scope of the installation work.