Don't throw away those bad fluorescent bulbs!

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Cmdr_Suds

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I have found that when most(more then half) fluorescent bulbs appear to be bad in a fixture with a magnetic ballast, they will work fine in a fixture with an electronic ballast. I am currently experimenting to see how much longer they last. I assume that this probably because of the higher frequency and/or starting voltages to the bulbs.

Any thoughts?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I have found that when most(more then half) fluorescent bulbs appear to be bad in a fixture with a magnetic ballast, they will work fine in a fixture with an electronic ballast. I am currently experimenting to see how much longer they last. I assume that this probably because of the higher frequency and/or starting voltages to the bulbs.

Any thoughts?
My experience has been that if the bulb is not working in a magnetic ballast fixture and the ballast is fine then the light output of the bulbs are probably not worth recycling.

Have you done a lumens test to see what the lumen output is. I suspect the bulbs won't last that much longer but would love to know more.
 

mcclary's electrical

Senior Member
Location
VA
My experience has been that if the bulb is not working in a magnetic ballast fixture and the ballast is fine then the light output of the bulbs are probably not worth recycling.

Have you done a lumens test to see what the lumen output is. I suspect the bulbs won't last that much longer but would love to know more.
I agree with Dennis, they're on their last leg, they have long ago lost their 7-10% output reduction in Lumens that is average, I wouldn't install them anywhere other than my own shop
 

peter d

Senior Member
Location
New England
Last I checked a brand new 4' T8 CW is about $1.20 wholesale and a T12 is around $1.

If it's not working, it's going in the trash.
 

Cmdr_Suds

Member
My point wasn't to suggest that you should start doing this as a business practice. That would be silly, especially since someone else is footing the bill and its probably not what they are paying you to do. My point was that a dead bulb may not actually be dead.

I live in an older house with many fluorescent fixtures, most still have magnetic ballast. When the bulbs in those fixtures quit working, I move them to a fixture with an electronic ballast and so far I have been getting close to double the life out of them. Maybe that is a good reason to simply change all of the ballast to electronic. But until I win the lottery, I will pinch my Penny's where I can for my own personal use.

As for reduced lumen's, it has not affected my normal going ons or even been noticed by my family. I recently worked on a building for a major corporate client that required me to reduce the lighting levels by 15% below ASHRAE standards in order to promote their "green" and "sustainability" practices. Go figure.
 

mcclary's electrical

Senior Member
Location
VA
My point wasn't to suggest that you should start doing this as a business practice. That would be silly, especially since someone else is footing the bill and its probably not what they are paying you to do. My point was that a dead bulb may not actually be dead.

I live in an older house with many fluorescent fixtures, most still have magnetic ballast. When the bulbs in those fixtures quit working, I move them to a fixture with an electronic ballast and so far I have been getting close to double the life out of them. Maybe that is a good reason to simply change all of the ballast to electronic. But until I win the lottery, I will pinch my Penny's where I can for my own personal use.

As for reduced lumen's, it has not affected my normal going ons or even been noticed by my family. I recently worked on a building for a major corporate client that required me to reduce the lighting levels by 15% below ASHRAE standards in order to promote their "green" and "sustainability" practices. Go figure.

Thanks for clearing that up, as I said , I would use them in your shop or home to save money. That's interesting, I've never tried that.
 

ty

Senior Member
I would definately use them in my own unfinished basement storage areas. Those lights are not on very often as it is.
But I'm also not going to save and store hundreds of bulbs, either.
 

broadgage

Senior Member
Location
London, England
There are two main failure modes for flourescent lamps.

1) breakage of the heater at one or both ends
2) cathode wear-out, wherby the heater is electricly intact, but wont emit sufficient electrons to light the lamp.

If the heater is open circuit, then most switch start or transformer start, or semi resonant start ballasts wont light the lamp. Such ballasts rely on a continous current path via both heaters for operation.
An electronic ballast, or some types of instant start magnetic ballast will normaly strike the lamp since they apply a high voltage to the lamp and dont "know" if the heaters are sound or not.

In the case of cathode wear out, then it depends on the internal circuitry of the ballast. A failing cathode will emit enough electrons to light the lamp provided that it is hot enough.
Ballasts that pass current continually through the heaters will often light a failing lamp. Alternatively runing the lamp on a higher output ballast may succeed, since the greater lamp current results in the cathodes running hotter.

It can be an interesting experiment to light a dead lamp thus, but I doubt that it is worth the trouble, remembering the very low cost of new ones.
 
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