Congratulations on starting your ebrewery!
While you're still in the planning phases, make sure you read the electrical primer in this forum. Here's the link: http://www.homebrewtalk.com/f170/electrical-primer-brewers-145019/
You'll find your answer here: Watts/Volts=Amps
There is additional information in the primer regarding the use of 240v elements at 120v.
Keep asking questions and keep us up on your build.