Continuing my basement shop brainstorming…
As I said in another question, the good news is that I've got a 30-amp 240V circuit more or less in the right place and available, and easily accessible for its entire length.
The questionable news is that it's a 3-wire circuit — no safety ground. It's in conduit, but I never like trusting the continuity thereof.
So: How insane would it be to run a new safety ground outside the existing conduit?
… Or should I just scrap the old run and redo it as NMC/Romex?
… Or should I put a GFCI in the new secondary box on principle (probably!), in which case safety ground is mostly moot? I've used that solution for several outlets that had the same problem..
Best Answer
Pull out the wire that's in conduit, (look it over, but it's probably just fine) pull in that wire and a ground.
It's darn near impossible to pull in another wire without pulling the whole bundle out and back in. It's fairly straightforward to pull the whole bundle out, add a wire and pull back in, unless the conduit is too small.
Code-wise, (250.118) properly installed metallic conduit (RMC, IMC or EMT) is a ground, whether or not you personally like it. It's not copper, but it's got a large cross-sectional area and the fittings are designed to maintain contact if properly installed.
I would not consider Romex an upgrade. I've seen too much rodent/Romex interaction to love it much, and with the possible exception of wire old enough to use cloth-based insulation as primary there's little benefit to "new wire" over "old wire."