Unless he multplexes the lights when they are turned on, you are correct, in fact with 3000 lights on at one time 12 VDC @0.18 A = 2.16 Watts per bulb. 3000 x 2.16 = 6480 Watts! 6480/120 = 54 A or 6480/220 = 29.45 A, this would require dedicated electrical service. I would say that multiplexing the lamps when they are turned on is a absolute requirement.