I'm not an electrician or master grower by ANY means, but I think I have to agree with Ocotillo. If opening it won't void the warrantee, you should do it. I can see 1 of 3 things leading up to this:

1) A mislabeled ballast.(Only a sticker right?)
2) As was said earlier, maybe it only runs 150w. Highly unlikely if it is labeled 250w.
3) Someone shipped you the wrong light and you got 100w for free.
budlover13 Reviewed by budlover13 on . I have a really stupid question I purchased a 150w HPS light system last year and just noticed on the light it says it's a 250w system. Is this normal? Can I use a 250w bulb if it says it's 250w system? See. Told you it was stupid. :p Rating: 5