First of all ALWAYS use a GFCI when you are around water.
Second is this a polarized plug?
I'll explain, Is it a 3 prong plug or a 2 prong plug?
A polarized plug has 3 prongs and IF the outlet is wired correctly it can be inserted only one way.
If it is a 2 prong plug try turning the plug around. This is not a cure!
I suspect you might have a short in the ballast that controls the actinic bulbs.
This is dangerous and needs to be looked at.
Also some 2 wire plugs have one blade larger than the other, the smaller blade is the HOT the larger blade is the neutral.
You might just have a lose wirenut allowing a stray wire to touch the light case.
Please unplug the fixture before taking anything apart.
Some MH ballast are multi-tap meaning they can be wired for different voltages. ALL unused leads on this ballast must have tape or better yet, wirenuts on them
110 volts can be deadly