Electrical drain, battery won't maintain charge?

[36tudordeluxe]

I have a 12V negative ground electrical system system with alternator in my '36. Am told that I should not see sparks at all when hooking up battery cables; I do whenever I hook up the positive cable. I have two fuse panels, one for switchable accessories and one for circuits that remain hot. I have pulled the fuses one at a time for all circuits but continue to get spark at positive cable. where do I go from here?