Metal Halide lights cycle (turn of and on)when at the end of their life. Also HPS and MVR Lamps. I work and custom build many different types of HID Lights and that is the most common problem. The Gases in the lamp are not staying ignited. I have seen ballast go bad but most of the time its the lamp, When a MH lamps is at the end of its life it the gas wears out. The pressure in the tube increases and requires more voltage to keep it ignited, When the pressure in the tube gets to high the Ballast cannot supply it with the correct voltage and the lamp shuts down. . It could explode if the pressure reaches to high in the tube. best bet is remove it. But im highly doubting its the ballast. any questions ill try and help out. You are local I could check it out and see whats wrong. I have a 250de 14k here I can give ya its used but free.
