I put the meter to our lights last night. 5.1A on the tree (11' tree), and another 1.8A on the railing (about 26 linear feet of railing). I tried to get my wife to tell me how many strings she used... her answer? "all of them" lol. Apparently she lost count. I reckon it's about 20 or so.
Will cost roughly $27 to light 18 hours a day for a month.