Greg, if there are boxes intended for mounting to steel, then I am simply astounded that ther is no 'idiot proof' bonding already incorporated.
Cost? As the AFCI advocates will point out, cost is not a consideration. Any wiring method has to be suitable for it's use ... and perhaps we have to re-think this expanding acceptance of Romex. With Romex being expanded in scope to commercial buildings, there will be many more opportunities for it to encounter metal studs.
Heck, with all the fuss AFCI's have caused, perhaps we ought to re-think Romex alltogether. After all, there's all that concern about the 'errant staple.'
I'm not being critical here; rather, I'm showing my ignorance. I just can't see Romex in either metal studs or commercial uses.
