Well am in the process of fitting the Stepdown Transformer (Hope its the correct one).  I think Gavin answered this question but need to verify - 240 v in, no problem - 3pin plug goes to 240 powerpoint, 115v out -earth wire (obvious,to earth),2 wires left - one to the main transformer other to fuse holder - question is, can I connect either wire ? 
The white usa to aus adapter and 3 pin plug is my add on ( Hate exposed wires)