1.5 ft High? Working with that box is going to be like building a ship in a bottle. Are you planning to use this box just for veg space (doable) or for both veg and bloom (not going to happen).

Let's figure that your pot is going to be at least 4" high. That will leave you with 14 inches to play with to each side of the light.

Underneath the light, you have even less: If the bulb and fixture take up another 4" of vertical space, and you have to keep some separation between the top of your foliage and the heat of the bulb - let's say 1.5" cause this puppy is going to get warm. That means you've only got 8.5" right under the light to work with.

So, you've got two areas toward the ends that can have plants which won't smack into the roof until they are 10 inches above soil.... and the middle where your most intense light is located you are limited to 4.5 inches above the soil/medium surface. YIKES.

Then you have the problem of light distribution: Your light source will be just below roof level, dead center in your space. In order for it to provide light to all plants, they need to be spread in an even canopy under the light - this little cabinet will quickly become choked with foliage which will block light from neighboring plants.

As for blooming.... Figure around a 1/3 increase in height during stretch, Which means you need to start bloom when the plants are small enough that you still have room to deal with the extra growth that will take place.

I would say that this cabinet could work for a veg space - when you get ready to bloom you will need a second cabinet.

I would not recommend putting a single 125 envirolight in the middle of this cabinet, however. Since you only need enough light intensity to penetrate through a few inches of canopy, and you want to avoid having plants shaded by their neighbors, I would suggest spreading the light across the space with smaller bulbs. At bare minimum, I would say two bulbs, each about 9 inches from the opposite ends of the cabinet (centered over their respective halves)... Better would be three or four bulbs distributed through the space. 4x42 would be much better than the single 125 in this space. Bonus: You can find them at Home Depot.

This cabinet COULD work for veg space.... but it will still be tight.

I actually consider my grow space to be just about the bare comfortable minimum for vertical space. My veg space is 2 ft high - Floor space is 1.5' x 2.5' with approx .25 ft^2 which is wasted space, leaving 3.5 ft^2 to work with. Since I'm using 7 cfl bulbs in this space, the two heftiest being 42 watts, I have an even distribution of light and heat - I could let the plants touch any of these bulbs without harm.

My bloom space also has 3.5 ft^2 usable floor space - and is quite a bit taller than what I need. In fact, I have quite a bit of unused space above my lights that I don't need or use. I could get away with 3' of vertical space for bloom. Blooming under CFL with good ventilation, I could probably get away with 2.5 ft of vertical space - but really anything shorter than that just wouldn't be practical except by changing to a sea of green with tiny plants.