Originally Posted by Poobah58
Can't imagine why someone would leave wire dangling with tape on them. Don't care if the breaker is off. How many wires are there? You'll need 4 if you want 240v and 120v circuits. That being said what you want to do is easy. My feeling is that if you have to ask these types of questions, get a professional to do it!
Unfortunately, I agree. However, folks can always learn (I did).
It sounds like you'd easily be able leverage the existing wiring to do some brewing outdoors. 50 amp should be big enough to do just about anything you'd want to with up to two 5500watt elements running simultaneously.
I'm going to assume that your hot tub had the spa panel with it when they removed it and all you have now is a 50A breaker (not GFCI protected). What you may want to do is run a spa panel outside using the existing wiring and then go from there to your required receptacles in an outdoor gang box or two via some conduit. Then some sort of portable control panel for your brewery.
And yes, you can run 120v off a 240V circuit using just one of the hot legs and the neutral and ground (you need 4 wires as mentioned above).