Lighting with wrong sized ballasts?

[bob`_your_dog]

Okay, i just back from a friends place and found a old 18 watts 10 000k Bulb, now this was just to tempting so i gave him 5$ and brought it home. Now i'm currently runnig a 25w 6500k of a 30 watt ballast, so i whiped that one out and replaced it with the 18watt. My tank looks a million times better! But now on the ballast it says run 1-30watt, or 2-15 watts, or 1-22 watt. Now my 25 watt has been running of this thing for ages, but will my 18 watt last as long? and will it be running at 18watts, 22 watts, or maybe even 30 watts.

 

[bob`_your_dog]

Maybe i could run the 2 bulbs of my 40 watt ballast that powers my black light, then run the black light off the 30 watt, even tho it's a 40 watt bulb.

 

[RamJet]

Not sure how that works, you may want to call an electrician and ask them. I would be interested to know what they say if you do call.

 

[Great Lakes]

The confusing world of lighting.

IT really depends on the ballast. If it is an older style tar ballast, the results are iffy. Tar ballasts are heavy, produce more heat, and if you have a starter, require additional wiring. Not all tar ballasts use a starter, but starters are only used on this type of ballast.

Swiftly replacing these old dinosaurs are electronic ballasts. They are lighter, smaller, and produce much less heat. They are also more efficient, and easier to wire up.

What you are doing to your 18w tube on a 30w balast is known as overdriving, (OD), or overdriving normal output flourescent, (ODNO).

Overdriving wih an older style ballast prvides minimal benefit because the resistence of the 18w bulb to accept 30w of power creates more heat in the ballast therefore lowering its efficiency.

Electronic ballasts on the other hand, are far more efficient and will provide greater power to the bulb with less heat produced.

Many people have run bulbs with a ballast rated 4x greater than the bulb itself. The efficiecy is reported to still be in the 75% range et this level. This means that if you were to use a ballast designed to run 4x18w bulbs, and wired it to run just a single bulb, it would have a relative output of about 56 watts. Not bad eh?

Now in the real world, they don't make a 4x18w ballast that I am aware of. But take a 2x30w alectronic ballast, wire up a 18 watt bulb, and get an output realative to roughly 45-50 watts. Double up with another ballast and bulb, and end up with around 90 watts of light out of two 18 w bulbs. Not too shabby.

GL

 

[bob`_your_dog]

cool cool, because i bought anouther 40w ballast today (electronic), and i have wired my 18w to the 30w ballast, and my 25w to a 40w ballast, and my 40w to a 40w ballast. All of which are the old school types of ballast's. But now, i am considering running the 18w off the 40w electronic ballast but i'm abit worried about how long this bulb will last.

 

[Great Lakes]

I ran bulbs this way for over a year with no noticeable difference in performance.
I was triple driving four footers. Man were they bright!

G L

 

[bob`_your_dog]

You serious!?? So if i get a 120w ballast i can run my 40w stronger than a pair of T5's? cause if so i'm taking this 40w ballast back and getting the most powerful one they got.

 

[Aquascaper]

This brings up another question, this time for Metal Halides. Can you 'Overdrive' Metal Halides?

I have a 400w ballast running a single mogul 400w bulb, could I run 2 x 150w bulbs off it without causing my flat to catch fire?