I have done that kind of work on concrete high-rise condos. All forming was with wooden form panels.
Typically used 4x4" shallow boxes with an appropriate mudring. Then nail them on with a couple of modified 3-1/4" common nails. (nicked with diag. cutters so they snap off easily after the forms are stripped.) Utility and masonry boxes work also.
ENT (cor-line, smurf-tube, etc.) or rigid PVC for conduit. Usually stubbed up out of the wall - then tied into the next suspended slab/floor.
