I have an older home where some of the house has updated electrical and some doesn't.
In a few rooms I still have several of the 2 prong outlets with no ground wire in the box and I want to replace them with 3 prong tamper proof outlets with proper grounding.
If I had an easy way to run a new line from the panel I would not be wasting your time, but I live in a split level home and several of these rooms have their lines fed from below, in-between floors, so I don't have any way to run a new line easily.
I know I can add GFCI outlets for some human protection but I want to do better.
I need to know if it is safe and/or legal to run a ground wire from a junction box in my attic (there are several) down the wall to use as ground when I replace the 2 prong with a 3 prong. The junction box likely leads back to a different circuit but it is all originating from the same panel (I only have 1)
Best Answer
This is fine, provided you're under a new enough Code
The 2014 NEC added a new point 4 in 250.130(C):
that, along with 250.134(B) exception 1:
lets you do precisely what you are describing (running a separate ground wire to an existing point on the equipment grounding system originating from the same panel).
The minimum wire needed for this is a 14AWG bare or green (THHN) wire, but I would use a Bare Armored Ground cable instead (to make it clear to future remodelers that this isn't something they can just cut through willy-nilly). You will also need the Bare Armored Ground cable if it's exposed to physical damage to comply with the protection requirements of 250.120(C).