bad for ballast?

[Orionrising]

Is it bad for ballasts to leave few bulbs out?

Just got done installing lighting in my woodshop and I think I put up too much

Thinking of leaving one or two bulbs out of the quad t-8 fixtures.

 

[cybrdyke]

It's not bad for the ballasts. It could be bad for the lamps. With a standard T8 ballast, when you remove 1 tube, the others brighten up a little bit. When you remove 2 bulbs, the others brighten up again. At this point, you could be running the 2 remaining tubes at a level that is higher than they are designed for. This could hurt the life of the lamps.
But lamps are relatively cheap, and depending on how many hours you intend to spend in your garage, it may not make much difference in the long run.
Good luck
CD

 

[Platonic Solid]

In addition to slightly increasing lamp lumen output as CD explained, this is known as "delamping". A common practice done intentionally to improve efficiency. You'll get higher Lumens per Watt running 2 or 3 lamps on a 4 lamp ballast than you get by using a 2 or 3 lamp ballast.