Hi, for your information, with or without plaster ceiling design is depending on your own selection. If there is no plaster ceiling, your lighting conduits will be exposing, and it will more to industrial feel like what you see in cafe, for example. ( If this is your intention).  However, it is not recommended if you are looking for a clean and sleek design in home (typical design), and with plaster ceiling, it minimizes alot of work. However, if you go for industrial mood, yes it is definitely possible