Larger Circular Bulb Always burning out fix?
#1
Larger Circular Bulb Always burning out fix?
Hi I have two circular bulbs on the kitchen ceiling the outer larger one going on very slowly and it gets black on the end. i have to replace it every couple of years but the center smaller bulb is still going strong. what causes the larger outer bulb to act up so much? please see attachment
<img src="https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/150x150/image_2020_11_14_112105_cb797ba226ab606fdadfae97ddbca0767d814933.png" width="150" height="150"/>
this is the picture here!
<img src="https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/150x150/image_2020_11_14_112105_cb797ba226ab606fdadfae97ddbca0767d814933.png" width="150" height="150"/>
this is the picture here!
Last edited by pcboss; 11-15-20 at 06:58 PM.
#2
There could be many causes such as failing ballast. voltage sags/spikes, intermittent loose connections.
I would recommend converting the fixture to a direct drive LED lamp. Do not use "plug and play" lamps.
I would recommend converting the fixture to a direct drive LED lamp. Do not use "plug and play" lamps.
#4
It is pretty easy to bypass the ballast and direct wire a fixture to use LED lamps. If you have any questions I'm sure there is a great DYI forum page out there that can help you out. 
Can you post what the lamps are? Should be marked on the lamp itself.

Can you post what the lamps are? Should be marked on the lamp itself.
#5
I'm not sure if they offer round tube LED replacements but now would be a good time
to upgrade the entire fixture. Stay with something round or go square.
to upgrade the entire fixture. Stay with something round or go square.
#8
Wow! that is a nice fixture those are classic and way better then any modern imported LED piece of CRAP that are being sold as "long life" lighting.
I'll take that off of your hands if you replace the whole fixture I can pay shipping for it I love these old classic "Circline" fixtures.
Most of these have one ballast with two 4-pin connectors one goes to FC8T9 (Smaller 22W one) and the other goes to the FC12T9 (Larger 32W one) you have to make sure those go to the correct lamp otherwise it may cause the issue you have here.
I'll take that off of your hands if you replace the whole fixture I can pay shipping for it I love these old classic "Circline" fixtures.
Most of these have one ballast with two 4-pin connectors one goes to FC8T9 (Smaller 22W one) and the other goes to the FC12T9 (Larger 32W one) you have to make sure those go to the correct lamp otherwise it may cause the issue you have here.
#9
If you prefer to keep it original, I'd recommend looking for an electronic ballast for FC8T9 + FC12T9. You might need to remove the built-in sockets and wire it to the fixed sockets of your fixture, but that shouldn't be too much trouble.
If it's always the same end of the large lamp that's blackening, it could be a cathode heating issue. Before changing the ballast, I'd confirm that all the wires leading from the ballast to that socket are snug, and that the contacts are not damaged or corroded.
It's hard to say for sure if it's a problem. Every two years or so for a fixture used every day isn't too terrible. If it was every two months, that'd be a defect for sure. Still I'd agree you ought to get a bit more out of it.
If it's always the same end of the large lamp that's blackening, it could be a cathode heating issue. Before changing the ballast, I'd confirm that all the wires leading from the ballast to that socket are snug, and that the contacts are not damaged or corroded.
It's hard to say for sure if it's a problem. Every two years or so for a fixture used every day isn't too terrible. If it was every two months, that'd be a defect for sure. Still I'd agree you ought to get a bit more out of it.