I see this often, residential surface mounted loadcenter with like a 2" pvc going up and through the ceiling in garage. I have always removed that and put wood and stapled cables . I looked at 312.5c exc. a-g, seems like a lot to assume would be there. Do you guys just use the excitsting pvc sleeve? Would save me a lot of work, but I don't think its within code. Am I missing something?