Which wire to use for wiring under drywall?

Is it possible in a gypsum corton ceiling for four spotlights with a power of 40 watts to lay a 3X1 PVA soft wire to each or is it better to use a 3X1.5 non-combustible hard wire in one core? No one can give a clear answer. It seems like PVA serves much less, it is combustible, and the contacts are oxidized, etc. and this wire is not used for wiring, but is used only in extension cords. A non-combustible wire 3X1.5 lasts longer and is considered safer. Access to the ceiling will be absent.