I've got a few problems with your arrangement. The short version? Fire the handyman, and hire an electrician!
As a general principle, you should open both of the "hot" wires. While I don't think switching only one side caused the failure, switching both sides of the circuit does make for a much safer installation. It's hard to remember that everything in the fixture is "hot" even though the light is out.
Which leads to the next detail ... that photocell is switching 220, not 110. I suspect a 220v rated photocell was used; a 110v version wouldn't last very long.
800 watts of MH lighting is pushing the limits of the photocell; this kind of lighting is much more demanding of the switch than ordinary light bulbs; photocells are typically rated at much lower wattages for "tungsten" uses.
A preferred way to instal this system is to have the photocell operate a contactor, and let the contactor actually operate the lights. This arrangement, would also alllow you to add a timer, or a manual bypass switch (for testing). (Do you really want the lights on all night?)
While the ballast is being replaced .... there seems no pattern to their lifespan .... you should have all the components replaced ... that is, the ballast, the igniter, and the capacitor. They're sold as a set.
The electrician should have a one year guarantee on his work.
If the bulbs are more than three years old, you might as well change them all at once. While you're up there, check the ballast and fixture for marking indicating what sort of bulb should be used ... there ought to be a marking along the lines of "M400."
