MH issue - Bulbs burning up

Hoping someone can help steer me in the right direction.
First the back ground details.
Fixture is 3 years old. It's a Giesemann Infinity 48 inch with (4) T5's and (2) 250 Watt double ended MH's.
We've got a new maintenance crew and they've changed out our bulbs. After about 2 weeks one of the MH's burned out and I think the T5's on that same side as well.
They never replaced the T5's (only took them to the shop for testing). Never told me the results. They replaced the MH and again, after a few weeks it burned out. I'm pretty sure I swapped ballasts to rule that out.

What could cause the bulb to burn out after a few weeks?

 

Sounds like a ballast issue or a short in the wiring. Could be bad connections to the ends of the bulbs.

 

What brand bulds are they using. Without knowing that, it's hard to point at the ballast as the problem.