Delamping & Ballast Damage

[peebee]

Does anyone know the reason why removing a fluorescent lamp can damage the ballast?

Is this true with both magnetic & electronic ballasts? Do they have similar reasons for failing?

 

[pennpoint]

peebee
Is this somthing you have experienced or is it a cautionary note provided by the manufacture or ????
I have never come across this ever. I have removed tubes bunches of times with power on the ballast. I liken it to unscrewing an incandescent bulb with the power on. I have never been cautioned not to do it.
This looks like a learning opportunity.
pennpoint

 

[peebee]

I've heard the warning several times from several sources.

Personally, I've never seen a ballast damaged in this manner -- in fact, when PC's started moving into the engineering office scene 10 years ago, it was pretty standard practice to stand on your desk and pull a lamp out to cut the glare on the screens. Never saw one smoke.

I'm wondering if the thought is that the ballast will sit there with a high voltage on it trying to start the arc across the lamp (which is no longer there), and the continuous overvoltage causes a problem. Just a guess.

A Google search led to the following links that include a warning that pulling lamps can damage the ballast (although none of them explain why or mention if this applies to magnetic or electronic ballasts):

http://www.co.marin.ca.us/depts/CD/main/pdf/BEST_pdf/GB_standards/Final_General_Standards_Energy.pdf

http://edis.ifas.ufl.edu/pdffiles/EH/EH16900.pdf

 

[advidana]

my experience is on the cheap magnetic ballasts use in residential garages, if one lamp is removed the other lamp will have a shorter life. I have not seen the same results with with commerical P rated ballasts, but the lamp and ballast representive I have talk with say that the lamps will have a shorter life and the ballasts will get damaged.

 

[sdmays]

I realize this is an old post, but perhaps someone will look at it at the present.

I know of one particular failure mode associated with removing a lamp from an electronic ballast. If the lamp is removed WHEN approximately the rated current is flowing through the lamp, a voltage spike (think inductive kick-back) can occur at the secondary of the transformer transferring energy to the lamp. This voltage spike can be reflected to the primary of the transformer and it can take the switching transistors. A common way to handle this failure mode is to use a transient voltage suppressor (TVS). If the lamp is dead, and the ballast can no longer power the lamp, the high voltage at the secondary of the transformer is typically not an issue (thanks to UL).

If you have a magnetic ballast and you do not have a circuit interrupting lamp holder, a great arc can occur and the metal of the lamp holder may not be able to withstand the heat from the arc (this is from a more senior engineer standing beside me as I type).

Of course, if the ballast is attempting to power the lamp, the lamp sockets can pose a safety hazard.

 

[brianhed]

Last month, I fried a new T-5 electronic ballast by taking out and putting back one of the HO T5 28w bulbs.

Power down those new t-5 devices first!