Dont overload your power supply, its worth noting that you can do this quite easy daisy chaining,
Not sure its correct but this is how i figured mine, i have around 20 building on 4 power supplies, count all leds on building multiply by 20 this is your milliamp load minus sign, so i count that as 2 leds or 40mA just to be safe, dont exceed milliamps on power supply, anybody want to chime in, please do
Each building has different number of lights and a sign so try to balance each power supply.
I got my plugs screw ready from china, 10 for $2, i believe, only had one so far out of 20 with issues, at that price, still happy. Cheers