Ground & neutral isolation/separation

Has ground & neutral isolation/separation at remote distribution panels always been required within the same structure? Thanks in advance.

The short answer - Yes.

I took a look in the oldest NEC book that I have which is 1940 and separation was required back then, I would guess that the requirement is in earlier editions as well.

That’s good to know. I inspected a rural home on Tuesday with service disconnect at garage (opposite wall of meter) with three remote distribution panels, grounds and neutral bonded throughout. After first panel 2nd two only had 3-wire feed, no conduit. Most of the wiring was installed in the late 70’s early 80’s.

Called it out and now “electrician” is questioning me.