Which bulb to replace in a fluorescent 2-tube ceiling fixture?

Old 01-27-18, 06:06 PM
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Which bulb to replace in a fluorescent 2-tube ceiling fixture?

How can you tell what fluorescent tube (bulb) to replace in a standard 4-foot, 2-bulb ceiling fixture?

I'm referring to when the light starts to flicker or not come on full brightness anymore. Eventually, the light goes out entirely. Is there a way to tell which bulb is causing the problem? I know one bulb aging or going out can affect the other light. I've read some places that you simply replace both bulbs. You don't bother trying to figure out which one is the problem.

Thanks in advance.
Old 01-27-18, 06:12 PM
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Rule of thumb..... change both at the same time.
Now would also be a good time to consider switching over
to LED replacement tubes,
Old 01-27-18, 11:02 PM
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PJmax: Thanks for the quick reply. Since you mentioned it, do you have any favorite LED replacement tubes or resources to read about them? I've read a little, but the cost is still prohibitive for me.
Old 01-27-18, 11:26 PM
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Really depends on how cheap you are and if you happen to have a case or two of used but serviceable bulbs from an energy saving transition at a warehouse...lol. Yes, at one time I had 2 cases of used bulbs. and I used them judiciously for some unknown reason? Cause I'm a miser in training? I only had 4-2 tube fixtures in my garage and 2-2 tubers in my kitchen. So I had enough replacement bulbs for 10 yrs or so.

Anyway, if you look at the bulbs, the ends of the bad one are normally dark grey. I mean the actual glass tube. If you look at working ones you'll notice the darkening as they age and you can pretty much plan to replace them. The larger and darker the grey/black area, the more worn out they are....usually.

That said, it's best to replace in pairs as the light output and color rendering can be quite different between new and old.
Old 01-28-18, 04:32 AM
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Whenever a fluorescent fixture or bulb goes bad I replace it with LED. I prefer the type bulb that operates on line voltage. You disconnect the ballasat and wire the fixture according to the instructions that come with the LED bulbs.

I have gotten bulbs from SuperBright LEDs and from Amazon. And all the bulbs have been good. The big benefit of SuperBrightLEDs is they have very complete technical specs and product descriptions if you're into the that. But, you will be installing a T8 LED bulb. It doesn't matter if your old fixture took T8 or T12 bulbs the new bulbs will be T8. The pins on the end are the same so they will fit in your fixture.

You will also want to pay attention to the color temperature of the bulbs you get. A lower number has a warmer color that might be better for a kitchen or somewhere inside the home. A higher color temperature is a whiter light and also usually a bit brighter but they can be a bit cold and harsh looking in a home kitchen.
Old 01-28-18, 05:45 AM
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PD makes some good points about light color. I usually suggest to my customers the following...Go with cool white (5000K range) for work place areas such as work bench, kitchen sink and work area, office space, sewing room , garage. Use warm white (2700K range) for living room, eating area, bedroom or where a softer light is preferred.

BTW...color does not affect brightness (PD mentions that cooler is brighter), I know he does not mean that but it may appear that way. Look at the lumens. That is the brightness regardless of color. Wattage does not indicate brightness or amount of light. That just tells you how much you're paying the power company.

Personally I prefer LED cool white, but I'm not sure if changing over from a regular T12 40 watt to a T8 LED is cost effective. How long will it take for pay back on the cost of LED fixture (I'm talking built-in style), not hanging from a chain.

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