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Discussion Starter · #1 ·
Hello -



I'm running a florescent fixture with FOUR HO 55W T8 bulbs. I feel the current ballast doesn't power the lights to full capacity. How can I verify this and what kind of ballast should I replace it with?


Thanks
 

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I'm running a florescent fixture with FOUR HO 55W T8 bulbs. I feel the current ballast doesn't power the lights to full capacity. How can I verify this and what kind of ballast should I replace it with?
That's not a size I'm familiar with, and it's not a size I'm finding on Google or my usual suppliers. The first thing you have to do is identify EXACTLY what tubes you do in fact have, and what connector ends they have on them. I would recommend posting a photo of the tube labeling and also an end-on shot of the connector end. There are 3 major styles for T8s. (2 pins 1/2" apart like most common tubes... metal nub 1/4" across... and a weird little plastic oval nubbie with 2 contacts in it).

Also make sure you're not dealing with T5 or something wackadoodle... like germicidal lamps, we've had a run on people trying to knock together those.


Current ballast is meant for 32W bulbs.
Well, there ya go! Sounds like somebody just went off and bought J. Random ballast and slapped it in there, and what they got was the usual kind intended for the bog-standard 4 foot F32T8.

Every ballast has a sticker containing data about it, and a wiring diagram, and a shortened list of which tubes it supports. Also out on the Web somewhere, every ballast has a data-sheet/instructions listing the full list of which tubes it supports. You have to

a) positively identify exactly what your tubes are, and
b) seek a ballast whose labeling or data sheet says it works with exactly that.

Oh, and one more thing. You talked about dim running... Ballast Factor will have an effect on that. Some ballasts are tuned to intentionally under-drive or over-drive the tube at, say, 78% of tube spec, 95% or 115%. That number is the Ballast Factor and it's used by lighting designers to fine tune light levels. My office is overlit, so I'm getting some 0.71 BF ballasts for it. Another thing to watch out for when buying ballasts.
 

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Discussion Starter · #6 · (Edited)
https://imgur.com/a/h2jL0ui


This photo is the actual bulb. It's T8 with a G13 connector, and is in fact a germ bulb. With some rewiring, I plugged FOUR of these 3' 55W bulbs into a fixture meant for FOUR 4' 32W bulbs. I figured the reduction in their size would make up for the increase in wattage. Could have been a dumb assumption, but they seem to work fine.

I understand that using the wrong ballast "MAY" reduce the bulb life, but once the bulb is on, does it run at full lumens? Is there any way to figure this out? I would prefer to keep the setup as-is rather than having to purchase and rewire a new ballast.
 

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OK so that's the bog-standard 4' 2-pin T12/T8 tube form factor, and you found germicidal tubes that fit that form factor.

I don't know what to tell you. The ballast is not a match, and germicidal tubes are not similar to illumination tubes. There is no equivalent T8HO illumination lamp.


I can tell you that the ballast is going to try real hard to drive the tube at 32 watts x whatever its Ballast Factor is. Fluorescent tubes are basically a dead short once the arc strikes, so basically, the ballast is operating in "constant current" mode. The question is whether this is forcing the ballast into a voltage that it's not designed for, that might damage it.

As for durability, *shrug*, I don't know. I have some 8 foot T12VHO's (210W/tube x 2 tubes) that I converted to electronic ballasts with T12HO ballasts (110W/tube). They light up, and they work at 110W light levels. It's sort of like having a Ballast Factor of 0.53. I just don't know enough about how germicidal tubes work to know whether they'll be able to emit the right kind of UV at that power level.

Why not just get the correct ballas--- oh, right. So here's the thing. Germicidal tubes are different *enough* that their ballasts are unique, and are sold as germicidal ballasts. They'll be hit-and-miss at general ballast sellers like 1000bulbs. Your best bet is companies that sell germicidal tubes.
 

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Discussion Starter · #9 ·
OK so that's the bog-standard 4' 2-pin T12/T8 tube form factor, and you found germicidal tubes that fit that form factor.

I don't know what to tell you. The ballast is not a match, and germicidal tubes are not similar to illumination tubes. There is no equivalent T8HO illumination lamp.


I can tell you that the ballast is going to try real hard to drive the tube at 32 watts x whatever its Ballast Factor is. Fluorescent tubes are basically a dead short once the arc strikes, so basically, the ballast is operating in "constant current" mode. The question is whether this is forcing the ballast into a voltage that it's not designed for, that might damage it.

As for durability, *shrug*, I don't know. I have some 8 foot T12VHO's (210W/tube x 2 tubes) that I converted to electronic ballasts with T12HO ballasts (110W/tube). They light up, and they work at 110W light levels. It's sort of like having a Ballast Factor of 0.53. I just don't know enough about how germicidal tubes work to know whether they'll be able to emit the right kind of UV at that power level.

Why not just get the correct ballas--- oh, right. So here's the thing. Germicidal tubes are different *enough* that their ballasts are unique, and are sold as germicidal ballasts. They'll be hit-and-miss at general ballast sellers like 1000bulbs. Your best bet is companies that sell germicidal tubes.

All understood, thanks.

My application is different than the normal lights that are powered for several hrs per day. These lamps are turned on for a max of 20minutes at a time, and then allowed to cool. Does that make it any better in terms of ballast load?


I'm just trying to save myself the hassle of installing a new ballast, and the extra $$ involved.



I did a test with a UV meter, and it does seem that the reading is under what the lamps are rated for, which likely means that the ballast is not powerful enough. Is there a way to measure the total 220W lamp output? (4x55W)
 

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Discussion Starter · #10 ·
Does this sound feasible?:
The fixture and ballast takes 4 x 34W, for a total of 136W.
Would installing 2 x 55W and 2 x 25W be a better option for me?


I can imagine how stupid these questions may sound to most here, but I'm just trying to figure this out for myself :)
 

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My application is different than the normal lights that are powered for several hrs per day. These lamps are turned on for a max of 20minutes at a time, and then allowed to cool. Does that make it any better in terms of ballast load?
No, doesn't help a bit.

I'm just trying to save myself the hassle of installing a new ballast, and the extra $$ involved.

I did a test with a UV meter, and it does seem that the reading is under what the lamps are rated for, which likely means that the ballast is not powerful enough. Is there a way to measure the total 220W lamp output? (4x55W)
*puzzled* Do you want peak performance out of the light, or do you want to save money on ballasts? Make up your mind lol.

Sounds like you're in the throes of indecision. Go find and price the right ballasts and then make a judgment call and stick with it.

I would point out that if you're happy with what you have, and only want to double your luminous flux, people are literally giving away 4-tube 4' fluorescent lights on Craigslist. Just build a second one and Bob's your uncle. That'll let you light from 2 different angles also.

Seriously. On the way back from picking up a huge load of free fixtures, I checked Craigslist and saw *another* free fixture offer that was literally 1/2 mile off my route home. I rolled up with my car already 90% full of fixtures, the guy could not believe it, he was like "go Craigslist!"

I can't believe people aren't keeping the fixtures just to put LED tubes in em... but whatevs...



Does this sound feasible?:
The fixture and ballast takes 4 x 34W, for a total of 136W.
Would installing 2 x 55W and 2 x 25W be a better option for me?


Oh please. Stop LOL... Just stop. ROFL...

You've got a thing THAT WORKS. That puts you way ahead of 90% of the jackasses trying to wing-ding together germicidal lights from dumpster-dived fluorescent light bits who are laughably not even close. Seriously. Quit while you're ahead. Stick with your winning formula.
 
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