Where PVC is allowed, it is the gray electrical version and "elbows" don't exist for that, for good reason. You can't pull individual conductors through them, let alone 8/3 Romex.
Electrical, (gray) PVC uses various radius "sweeps" to turn corners, 45° and 90° readily available. Even with sweeps, most codes limit a "pull" to 180°, up to 360° or 2 to 4, 90° sweeps. Varies with conduit diameter and "fill", the volume of conductors in the conduit. More than that compromises the conductors strength and makes pulls impossible without power pulling equipment, which can destroy the conductors as well as "saw" through the PVC.
Romex is intended to be used in "protected" areas only. 1/2" drywall can provide acceptable, (though dubious) "protection" while Romex is usually not allowed in conduit by most codes. Few codes allow Romex under any circumstances in industrial buildings, other than in finished office spaces.
Starting from scratch, EMT, (thin wall
Electrical
Metallic
Tubing,
not flex) in 10' lengths, standard sweeps and pull junctions such as "LB's", with THHN single conductors would be my choice as to price, ease of installation, protection and acceptability by most codes. A few will demand the threaded "ridgid conduit" that is essentially water pipe, same ID's, OD's and threads, interchangeable.
If I had the Romex on hand, I'd figure out a way to use it, especially if I wasn't concerned about code inspections but the elbows you have on hand won't work at all to pull Romex through, even if it met code for exposed electrical runs. I'm assuming 8/3
AND ground, (4 conductors, one of them green) for 3 phase.
Under certain constraints, I have on occasion shoved various types of conductors through standard elbows. It's a pain and the run must be assembled one piece at a time, pull the conductors fully through, fight the elbow down over the conductors with
great effort, apply the glue to the joints, (and unavoidably, the conductors), shove another piece of tubing over the conductors etc. This not acceptable under any codes that I've dealt with.
I have met inspections with Romex in open framing by making U shaped boxes of 1X wood and/or plywood, the center piece lapping the studs for nailing/screwing and the 2 other parts cut to fit between the studs. This is better protection than the acceptable drywall. This "fix" is for minimum routing.
If it won't ever become a code violation issue, run the Romex tight to the framing members, back against the far side wall covering, on the sides of the studs and just under top plates, (your drill will hate you for that, competing with the nails) and you will provide the Romex with better protection than the "acceptable" open runs between studs, protected only with drywall. This "exposed" Romex could be acceptably protected with pieces of wood.
Bob
See what happens when you write too much stuff, everyone beats you to it.