I have never had an electronic ballast but the principle is the same. A ballast will only pull enough electric for the bulb. If you put a larger bulb in than the ballast the ballast is not rated for that much electric so boom.

However a smaller bulb than ballast and not as much electric passing through there by running cooler too.

My bro runs a 250 in a 600 and I run a 400MH conversion in a 1000HPS ballast.

I don't see why electronic ballast would be dif. I have seen the new ones you can adjust the power to the light to save energy.