I have a 1940's house. Modern panel and sub panel feeding cloth clad cable and knob and tube. Very hard to access crawl space or inside wall because wood ship lap over skip sheathing, shingles over skip sheathing outside. I wish to add grounds to a couple outlets near the panel and am happy to see the code now allows this. (I did it earlier with a green thnn, exposed, to ground rod, and know this is not right.)
I see "bare armored ground" cable suggested, and see this was used at both main and sub panel here. The only cable I can find on the net has monster conductor... like gauge 2,4,6... crazy big. The existing panels use an armored cable 1/2" at main. 1/4" at sub, with a conductor that looks to be about 12gauge max.
Can I find something like this? Should I just buy 1/2" armored cable and pull the white and black wires out? Will this type of solution be any better if routed into the panel and bus bar or (as appears from the code) just as good attached properly to ground rod?