I have a house built in the '50s, and some of the runs are done with what appear to be original 12/2 cloth-sheathed wire without a grounding conductor (just hot and neutral). I'm looking to install some new outlets on this circuit, and want to branch off an existing splice with modern 12/2 NM wire with a grounding conductor.
Is it acceptable to run a grounding conductor from my new splice to the nearest other splice that has a grounding conductor on a separate circuit? If so, are there any considerations for the wire that is needed, i.e. insulated or bare? If running a bare solid copper grounding conductor from box to box, does it need to be stapled?
Here is the part of the NEC which I think is applicable, especially 250.130(C)(1)
250.130 (C) Nongrounding Receptacle Replacement or Branch Circuit Extensions.
The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates
(4) An equipment grounding conductor that is part of another branch circuit that originates from the enclosure where the branch circuit for the receptacle or branch circuit originates
(5) For grounded systems, the grounded service conductor within the service equipment enclosure
(6) For ungrounded systems, the grounding terminal bar within the service equipment enclosure
See this diagram for reference as to what I'm trying to do. Box 1 is a junction in the circuit I'm branching off of (it used to power an old doorbell transformer that has since been removed), and Box 2 is a junction on a separate circuit (same amperage).
Im in Denver which follows the 2020 NEC. Thanks in advance.