Older NM cable with reduced size and insulated ground

[Jake@01]

I've done a lot of new construction on military bases & schools. All emt in walls is the usual spec. We would even pipe between can lts. The only Mc would be on troffer lts .

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[kwired]

No idea of why, but the 1968 code was the first one to use the full size EGCs for 30 amps and less. The 65 code permitted a 16 AWG EGC for a 20 amp circuit where the EGC was part of a cable assembly. It also permitted a 14 AWG for a 30 amp OCPD, and 12 for a 40 amp OCPD.

Was a little curious when, figured must been mid to late 60's though. I've seen plenty of 12-2 with 16AWG ground, Can't really recall seeing the others mentioned. Seems a lot of times they ran 10-3 (no ground) in places that could have or even should have had a bare or green instead of white, and 40 or 50 amp circuits almost always was 6 -3 or 8 - 3 with no ground or even used SE type cable.