Looks like whoever installed this didn't understand basic concepts of using electricity in a reasonably safe manner. That much smaller wire spliced to the heavy wire would worry me, in the sense that the smaller wire has not enough over current protection. Also, it looks like those smaller wires are not going thru a raceway (that the right term, yes?) like conduit. Just thru a hole in the wall....
Unless you can get them to let you rewire everything in this place, I wouldn't do anything there. There's undoubtly many more serious mistakes around there.
