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Rapid Start vs. Electronic Ballast bulb wear

American Locomotive

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My basement is currently lit with four, 4ft dual bulb T12 fixtures. About 6 or so years ago some bulbs went out, so I decided to do one last "fluorescent hurrah". I ordered 8 Sylvania 941 bulbs, which were probably the most advanced, most efficient and best T12 bulbs you could get. Full 40w power, 90 CRI, tri-color phosphor, 3000 lumens, yaddah yaddah. Basically T5-esque phosphor technology in a T12 bulb.

Anyways, shortly after I installed the bulbs, one of the magnetic rapid start ballasts in a fixture failed. I replaced it with an electronic ballast I purchased online. Cut to 6 years later, and things are a bit interesting:

On every one of the fixtures with a rapid start magnetic ballast, one bulb out of the pair is significantly dimmer with very black bulb ends. If you swap the bright/dim bulb positions, the dim bulb stays dim. So it appears that the bulb itself is damaged and starting to fail. However, on the fixture with the electronic ballast, both bulbs are still near full brightness, with very little blackening of the tube ends.

So I guess my question is two fold: Is it typical for a rapid start ballast asymmetrically wear the bulbs, and is it typical for them to be much harder on bulbs than electronic ballasts?

This is a more "academic" question than anything, as all of the lights will be getting replaced with LED when they finally fully fail. I just found it interesting that the magnetic ballasts seem to be damaging the bulbs compared to the electronic ballast.
 
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Bert_

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I don't know if the /941's have a cathode shield? Probably not.

A lot of the later rapid start ballasts had capacitors that drop in value. Result is low lamp current and sputtering. Damages the bulb.
 

walta

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Have you tried the weak bulbs in a fixture with an electronic ballast.

Generally, any lamp with a dark end is a goner.

Do you run the lamps much? 15,000 is the upper end of life expectancy. At 10 hours a 5 days a week and 6 years you could well be there.



Walta
 

Norcal

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If the lamps are blackened, time for a new ballast, & these days that means smart money says time for ballast bypass LED's, cheaper then a new ballast & more easy on energy costs.
 
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American Locomotive

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They will be replaced with LED. I was just more curious about the behavior of the rapid state ballasts vs. the electronic ballast. It might be fun to try the dim bulbs in the electronic ballast to see if they're just as dim.
 

kbuhagiar

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They will be replaced with LED. I was just more curious about the behavior of the rapid state ballasts vs. the electronic ballast. It might be fun to try the dim bulbs in the electronic ballast to see if they're just as dim.
I had the same damn problem in my garage and it drove me nuts. Finally pulled the trigger and converted to LEDs.
 

dscheidt

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So I guess my question is two fold: Is it typical for a rapid start ballast asymmetrically wear the bulbs, and is it typical for them to be much harder on bulbs than electronic ballasts?
yes to both parts of hte question, but it depends on how many starts the tubes see, compared to run time. If they're turned on once a day, and stay on until close, it's not going to be a problem. In a bathroom, where the switch gets flipped 30 times a day, they kill tubes very quickly. Programmed start ballasts are vastly better at this, but I don't think anyone still makes any, because fluorescent tubes are dead tech.

if I remember right, when i put programmed start ballasts in my garage the datasheet showed performance compared with various other ballasts (all from sylvania, who made the ones I installed). I forget the exact numbers, but instant start balasts with 10 minute run time cooked some tube in 400 hours, same tube in a programmed start ballast was expected to last 45,000 hours with 10 minute run time.
The garage tubes lasted 6 years, with lots of short starts (think go in to get a thing, 45 seconds run time, then go back in a few minutes to put it way, another 45 seconds...), with no visual change in performance or tube blackening. I replaced all the fixtures with led ones, because I got a smoking deal on some panels.
 
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