if the lights go off durring the veg cycle it is usaly ok but try not to make a habbit of spurratticly turning the light on and off of course it could cause it to hermi

a plant can be kept in several light cycles for veg 20/0 18/6 ect.. i find that the longer the dark period the more stretching my plants do so i use 24/0 a plant should remain in the veg stage until the onset of 12/12 for most strains

good luck-Bomb