I like the idea posted above about using a second set of receptacles downstream of the GFCI. I hadn't thought of that, but my box size is pretty small, so this could be a space challenge.
Jeff, thanks for your concern. I actually hire a local electrician to do brew work for me when I feel something is beyond my ability. What I have is a setup that was previously used as a sous vide temp controller, which I have converted to activate a small aquarium pump to function as a cooling system for a water bath surrounding my fermentation vessel. That works without issue, and I have the wiring down. What I'm adding is a simple outlet and power toggle to run my chugger pump manually. If I decide to step up to an embedded heating element in my 15 gallon kettle, I will likely build a larger controller with a proper heat sink using a metal box, much as others have done. Currently I'm using two Avantco 3500W induction burners for my BK and MLT. We'll see if that works out for the MLT (heating it directly with recirculation of the liquid using the pump). If not, I'll probably add a second pump, HLT and do a full HERMS like Kal's.
Originally Posted by jeffmeh
That's a 15a 120v GFCI. You could run one 1500w element from it drawing around 12.5a, and have a bit of headroom for your electronics and pump. You could likely make 5 gal batches with that element, although it would not be particularly fast getting up to temperature.
No offense meant, but the nature of your question leads me to recommend that you do quite a bit of research before undertaking the build, or find someone who has the electrical qualifications. Electricity is not something to play around with.