400w bulb and 250w ballast

Hi,
I have turned my 400w bulb hps not realising it's a 250 w ballast it turns on ok however just wondering if there is a hazard to this

Under powering is safer than over powering an hid bulb. HPS are stable compared to mh but you will decrease bulb longevity and have a spectral shift when not matched to the proper ballast.

Personally I would use the right bulb and ballast combo for peace of mind.

Good luck