Read this...
http://www.spadepot.com/spacyclopedia/w ... ub-spa.htmThen, Go to Spa Depot and buy a disconnect box. Then go to Home Depot and buy rolls (or whatever length you need) of #6 THHN wire. You need these colors, Red, Green, White and Black. Then buy some flexible conduit. Make sure you buy the connectors that go to the disconnect box to the PVC and the flex.
If you print out what I just said, with the picture you posted and take it to Home Depot and the Spa Depot, they can hook you up with all you need. Total cost will be $200-$250