The former. My house is 3 storey and has well over 100 lights, most of which were originally halogen downlights and spotlights (around 70), a bunch of incandescent wall lights, and some fluoro. Probably looking at over 5kW if they were all on at the same time. I’ve since replaced almost every fitting with LED.6 lighting circuits! That must have been built for a bunch of those high power halogen downlights that used to be popular... or a hydroponic enthusiast.