Can someone give me the output voltage range for a 250W metal halide ballast. I realize starting voltage will probably be considerably higher than operating voltage. Thanks.
What is your reason for asking? It's not really a simplistic issue.
The "Open Circuit" votlage coming from the ballast is usually somewhere around 350-400V, although the lamp voltage is usually around 135V. When the lamp is in the circuit, the lamp voltage is what you would measure on the output of the ballast though, the open circuit voltage is only relative to what you might read on a meter in that you can't really use it at that level, it drops as soon as you apply a load to it.
But "considerably higher" for the starting votlage? I'll say!
Strike voltage is 3-5kV, then if you have a "warm restrike" type (rare), it can be 25-20kV!