I'd find an electrician friend or friend of a friend, at this point you don't need any work done, just an identification of what's there - offer him a couple of beers !! Either way, I'm sure you'll be happy with the result - you'll probably just have to swap out an outlet with a $50 spa panel to have 50 amp GFCI power... It doesn't get any cheaper or easier than that ! At this point just find out the gauge of the wire and post back !!
15 gallons of Yellow Bucket Light
~1 gallon of Little Miss Muffet Cider
12 gallons of Under Pressure Brown Ale
5 gallons of Dead Guyish IPA for a competition