Here in Phoenix we don't see many cinder block homes. There is a 2x6 fur wall inside of all cinder block exterior walls. There are several exterior coach lights and when you penetrate the ussually hollow cinder block to travel the slight distance to the box (6in) do you need to sleeve penetration hole with pvc or use something elese? Also came across plastic electrical boxes with plastic L bracket for mounting on wall. Is masonary box required by code, in hollow cells etc as filled portions have already been filled?