Flourescent Lightbulbs energy usage?

Question

I'm wondering, if your light fixture is made to hold 4 bulbs, and you only put two in. Does this effect the energy usage, or the life of the bulb. Will the light fixture try to overcompensate the energy usage and use the same amount as if they was 4 bulbs in it, or will it save you money on the electrical usage. Does this effect the lifespan of the bulb?

Answer 1

It won't have any different effect on the individual bulbs whether you use 1 or 4.  The fixture was probably just designed that way to provide more light in all directions, but each socket receives the same voltage regardless of what's in the other sockets.

So yes, it will save you money and no, it will not effect the lifespan of the bulb.

Answer 2

If we are discussing CFLs

You should use as few bulbs as you need. No, they will not be harmed by being alone.

When we have the old long fixtures with a ballast, many of them will use electricity inefficiently with fewer bulbs than planned for.

Also, those old long tube flourescents ar likely quite inefficient  unless they are of the t8 electronic ballast type, and still best to have one that accepts only one or two bulbs.