I have a branch circuit that is reading open ground due to it being an old house and no ground was pulled to that circuit. I have to pull a 240v 2 wire (2 hot & 1 ground) to that general location and was wondering if it would be safe to pull in an extra ground wire next to the 240v line to ground the branch circuit or would it be unsafe due to there being no neutral in the 240v (could it induce a current into the ground wire making it pointless?)

Thanks,
Rez
Apprentice electrician in RI

If the receptacle is a non-grounding receptacle, leave it alone. "If it's not broke don't fix it."

NEC 2014 Article 250.130(C)(4) Nongrounding Receptacle replacement or Branch Circuit Extension "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"

If your area has adopted the 2014 edition of the code you are fine.

However, if you are at 2011 or earlier, then 406.4(D)(2)(a) thru (c). You either replace the receptacle with another non-grounding receptacle or use A GFCI receptacle that is labeled as not grounded.

Just install with the 2 hots. Pulling a separate ground, unless you are using conduit, is not code approved.

Mark, You are incorrect. The 240 V branch circuit is going to require a EGC. Under the 2014 edition of code, that EGC can be extended (as long as it originate in the same panelboard as the receptacle branch circuit) to the outlet that needs it.

I think some of the answers are missing the point. The OP IS running a 240v circuit with a ground... period. His question is whether he can legally add a second ground to supply the circuit in question. In my opinion Don has answered this correctly, as long as the ground wire is sufficient in size.