My home was built in the 1930s with knob and tube wiring. The previous owner(s) replaced or augmented it, a bit at a time, and when I purchased the home from the last one he said that there was no knob and tube wiring left, and from my trips into the attic I would say that is correct.
What there is, currently, is a hodgepodge of:
- Modern (ca. 2000) 12/2G NM cable.
- 1970s era 12/2G NM cable, but with a very light-gauge (estimate about 18G) ground wire.
- 1960s era fabric covered 12/2G Romex, again with a very light-gauge ground wire.
I believe that my current project will replace the last of the #3; I'm replacing the feeder to the back room which I use as a home office with 12/2G MC (and the appropriate boxes, clamps, etc....one "feature" of the previous installation was a joining of three cables with no wire nuts and a massive wrap of electrical tape). Downstream of there, though, are two receptacles fed with the #2 wiring which I can't go inside the walls to replace at this time. One feed is in decent shape electrically and I was just going to let it lie at present.
The other, though... well, I found when I first purchased the house (several years back) and tested the outlets that it had no ground. I went into the box and found the light-gauge ground broken off, with no slack to be able to pull enough into the box to tie onto. Since I wanted to use a computer on this outlet and needed a ground, I drove a listed ground rod just outside the wall and ran a green wire through the wall.
It has worked to quiet the electrical "noise" my system was seeing, but I know it's not code-approved. Now, though, with the other work I'm doing, although I'm still not ready to open the wall back there (1970's wood paneling which I can't match), my thought was to abandon the existing (#2) wiring in place, install an extender box on the current receptacle box, and drop a line of MC down from the ceiling as a temporary feed which will give me ground continuity back to the service entrance. When budget permits I plan to do a walls-out renovation of this room and I'll move the feed inside the wall at that time.
What should I do with the ground rod and wire I put in at this location earlier? Should I ignore and abandon it, or would it improve the grounding of the house as a whole if I tied it in to the new MC feed at this receptacle box? Looking for a recommendation as I move ahead.