if you're using 9vdc to power all your light bulbs from a central location, you're going to need a lot thicker cables since the amperage you're using is going t

if you're using 9vdc to power all your light bulbs from a central location, you're going to need a lot thicker cables since the amperage you're using is going to increase tenfold (or ~x20 for anywhere using 230v). and switching DC is going to be similarly more problematic since you won't have a 0-crossing 100/120 times a second to break any arcs, wearing out your switches