I'm looking for suggestions for a time for a 150watt metal halide light. I didn't know of a regular time would work, or if it needed to be special.
Most standard timers should work for your purpose. You should be able to look at the specifications for a particular timer and see the lamp rating. There should actually be two different ratings for most timers, a motor rating and a lamp (resistive) rating. I would give yourself a margin of error to account for any inrush from the ballast striking the arc.
If that sticker it's true, you could run whole rooms of lights off of it. 1250 Watts is a lot of light
I got it for Christmas lights last year. I'm trying it out today. The lights came on automatically. So that's a good sign. I work long shifts, so I was having to keep my light on like 13-14 hours which is way too long. I've got the time set for 6 hours.
I have the T5's on for 11 hours, the Halides on for 8 hours, and the led moonlights on for 12 hours at night
I run my LED about 14 hours I think ... they ramp up and ramp down early morning and late evening ...