Out grounding with NEC specific questions
Hi, I'm sorry for re-asking something that looks like it's asked several times a week, but I can't find specifics to my case, and trying to read through the NEC and it's making my head spin.
I have some ungrounded outlets in an old section of my house, the ungrounded wire (2 wire, 600 V) is not easy to trace, but obviously comes from some junction box, because every pair (triplet?) leaving the main breaker box is grounded to the grounding bar. I'd like to ground these outlets so I can use a computer/surge protector (sorry, can't use an ungrounded GFI). My thought is to run 12 gauge solid ground wire to one of the listed options in NEC 250.52 (A)(1)-(A)(7) or NEC 250.130 (C) are these the right places to be looking?
Option 1 is grounding to 250.130 (C) (3), however I believe this doesn't meet code because the junction box doesn't have a ground bar (?), but probably a wire-nut? But I don't remember for sure. It also is for a different circuit, or a parallel branch of the same circuit, but not a parent branch, is this a viable option? I can also ground to the conduit/junction box of a 220 line in the same location, but same problems as listed before.
Option 2 is grounding to 250.52 (A) (2), an I-beam that runs the length of the house and I can easily ground to, but I'm not sure the I-beam is connected to "earth" by one of those options, can I check the resistance between the house ground and the I-Beam and if it's less than 25 ohms (250.56) just ground to that? How else can I check if the I-beam is grounded in accordance with 250.56? Also if I do this, should I also ground the I-beam to the junction box listed above? I seem to remember reading that having two unconnected grounds can cause a "floating"(?) ground?
Option 3, this is the most work, and therefore the last option mentioned. I can ground to the first 5 feet of copper water pipe coming into the house from the earth, (need to verify it's copper, I'll have to use some paint solvent because the pipe's been painted at the only place where I can access it within 5 feet of the earth right after it comes into the house).
Do I have more options? What are or where can I find "Other Listed Electrodes" mentioned in 250.52(A)(6)?
These are the options I see for grounding the first outlet, the second outlet is wired to the first in a daisy chain with 3 wire romex, if I ground the first outlet does the second outlet meet code for ground?
As a partially unrelated question... I have one outlet that when tested, says grounded correctly, however when the power's off and I have the outlet pulled out, there doesn't appear to be a ground wire, could the outlet be grounded to the box which is grounded by the 2 wire+metal sheath (can't remember what it's called, sorry... ). When looking I don't see any conduit or ground wire attached to the box...
Thanks!
-David