7

Do fluorescent lights last longer if they are left on?

I had a boss who said this, and I was wondering if it is really true.

I would rather replace them with non-fluorescent, but the fixture doesn't really allow that, and I don't have the skills to replace the fixture right now.

The lightbulb is very new and has a Phillips circline / circular fluorescent bulb with the following characteristics: T9, 4 Pin (G 10 q) 1 and 1/4 inch diameter (1.25). Please see Home Depot Phillips fluorescent bulb

Thanks

Improve this question
8
  • 2
    Explain meaning of left on. 24/7 or turned off when you leave a room for a minute. Use them as any other light, turn on when in the room, turn off when leaving the room for more than a minute.
    – crip659
    Commented Aug 4, 2021 at 16:57
  • 1
    You'd have to provide a more specific scenario, with hardware model, usage patterns, etc. Otherwise we're speculating. It's all moot to my mind anyway as running power-hungry lights full time is a wasteful and irresponsible thing to do. We're frying this planet.
    – isherwood
    Commented Aug 4, 2021 at 18:39
  • 2
    It was true 50 years ago, but I doubt that it's still true.
    – Hot Licks
    Commented Aug 4, 2021 at 19:23
  • 2
    You can get LED replacements that are plug and play with existing fluorescents.
    – Barry
    Commented Aug 4, 2021 at 22:37
  • 1
    If your boss is over 80 years old, then it is likely true to them. If they are under 80 years old, then it's likely not true to them.
    – Amazon Dies In Darkness
    Commented Aug 5, 2021 at 9:06

5 Answers 5

Reset to default
16

There are 2 parts to tube wear & tear

Starts

Starting a tube requires "striking an arc" across a cold tube. These are, after all, in the arc-discharge light family. This will cause a modest amount of wear, or spallation, of material off the electrodes. (which you can see as a darkening band across one end of the tube).

This is helped by using "pre-heating electrodes" in the ends of the tubes - these will glow orange before the tube strikes.

Any non-broken fixture will provide tens of thousands of starts.

  • An Instant-start ballast, which slams the tube with extremely high voltage at the cost of more spallation of electrode material, will provide 10-15,000 starts from a tube.
  • A Rapid-start ballast uses the "pre-heaters" for 1 second before striking the arc. You can see the momentary delay after you throw the switch, and an orange glow on the ends of the tubes before the light strikes. These will give 15,000 to 25,000 starts from a tube.
  • A Programmed-Start ballast uses feedback data to run the pre-heaters as long as is needed. They start with a momentary delay, but that delay becomes longer in the cold. These will give up to 50,000 starts from a tube. This is so good that people use them on motion sensors.

Run time

Run time is less of a factor than starts. But we certainly don't expect 10,000 days from a fluorescent tube, do we? That means shutting off the tubes at least at night is a win for tube life.

To say nothing of the electricity in question!

Anyway, it's really a judgment call. For something like a bathroom, where the lights will be on and off constantly, you either want a programmed-start ballast, or you might think about leaving the tubes on during the day.

Think about tube wear versus ease of replacing.

Improve this answer
1
  • 7
    Think about tube wear versus ease of replacing. I remember reading years ago (can't remember where) about replacing all bulbs in a building either after 'x' time or once (except perhaps for an odd-ball very early fail) bulbs start going bad, because the labor in many situations of setup (schedule, get the ladder out, etc.) to do a whole building is a lot less than the labor to do 100 bulbs at different times, even though it means throwing out some bulbs that might have months (or more) of life left in them. TCO can get complicated.
    – manassehkatz-Moving 2 Codidact
    Commented Aug 4, 2021 at 19:18
8

The specifics will vary a lot depending on the particular lights. There are three components in a typical (non-CFL) fluorescent fixture:

  • Ballast
  • Starter
  • Bulb

Each of these can wear out, and at different times. My understanding of how these things work is that the # of cycles (on/off) will have more impact on the ballast and the starter. The amount of time on will have more impact on the bulb. But really too many variables for any of us to guess, other than to say it is not a good idea to flip the light on/off every few seconds.

I would rather replace them with non-fluorescent, but the fixture doesn't really allow that, and I don't have the skills to replace the fixture right now.

That is where it can actually get quite interesting. There are three ways to convert fluorescent to LED, at least if it is a typical ballast/starter/tube bulb configuration:

  • Install LED bulbs that "magically" work. Search for: Fluorescent Tubes LED Replacement With No Wiring (or similar). Basically the LED bulbs include electronics that are designed to work with the otherwise unnecessary ballast & starter.
  • Keep the physical fixture, bypass the ballast, and install LED bulbs. This requires some work. My synagogue had this done (electric utility paid for it!) many years ago.
  • Replace the entire fixture with a fixture that uses integrated LEDs. That is ideal, but highest initial cost. My synagogue had this done several years after the original ballast bypass installation (electric utility paid for this too!) a few years ago.

The first and second options are low to medium cost (unless subsidized by a utility or government agency as an energy conservation measure, which varies considerably around the world and changes over time) but are limited to the most common fixture/bulb types. The third option may be what your boss is thinking of, which is a higher up-front cost (unless subsidized).

Improve this answer
6
  • 3
    I'm getting to be less and less of a fan of fixtures with integrated (non-replaceable), LEDs. I've already had 3 fail within 3 years of installation which supposedly had a 20 year life span. One good option is for a typical 4' florescent fixture is to replace with LED tubes that work with the ballast or get tubes that completely removes the ballast and rewires it directly to the tubes. Code requires labeling documenting the change, but it's a good option. It preserves the original fixture, making installation easier.
    – George Anderson
    Commented Aug 4, 2021 at 17:33
  • 1
    @GeorgeAnderson You've covered all 3 of my suggestions in one little paragraph. In the end, whatever works best for you. We are so used to "replace bulbs" that replacing entire fixture seems absurd at times. But of course MTBF is the key - if they only last 3 years then replacing fixture is a little crazy. Like replacing a toilet when it gets dirty.
    – manassehkatz-Moving 2 Codidact
    Commented Aug 4, 2021 at 17:45
  • 2
    @manassehkatz-Moving2Codidact oooh watching that SNL hurts... reminds me of a production facility where they used lead solder at work stations: it was much cheaper to (correctly) dispose of a household vacuum cleaner annually, with only grams of lead bearing dust in it, than to have it cleaned.
    – P2000
    Commented Aug 4, 2021 at 19:50
  • 2
    @manassehkatz-Moving2Codidact I haven't watched SNL for decades, but that was hilarious. Thanks for the compliment on my short paragraph. Brevity is the soul of wit' is a Shakespeare quote and I'm no Shakespeare! Guess I got lucky on that one. Take care.
    – George Anderson
    Commented Aug 4, 2021 at 21:01
  • 1
    IMHO, SNL has largely gone downhill (as have so many other things...) over the past few decades. I used to watch it regularly when I was younger. In the last 20 years I've only watched it a handful of times - a few because of political stuff (some was funny, some not) and the Elon Mush show. The Elon Musk show was actually mostly funny (but controversial, of course), the others typically had one or two skits that were funny and the rest ranged between "meh" and "yuck". But the fake commercials from the old days were great.
    – manassehkatz-Moving 2 Codidact
    Commented Aug 4, 2021 at 21:30
4

As I recall it in the 80s and 90s, what used to fail first was the starter, and they were expensive to replace. Also, they used more power during start-up. Which is why the advice was to leave them on "for the day". That balance has changed, and now they can be switched off when leaving the room.

CFL Lighting Since they are already very efficient, the cost effectiveness of turning CFLs off to conserve energy is a bit more complicated. A general rule-of-thumb is this:

If you will be out of a room for 15 minutes or less, leave it on. If you will be out of a room for more than 15 minutes, turn it off. The operating life of CFLs is more affected by the number of times they are switched on and off. You can generally extend the life of a CFL bulb more by switching it on and off less frequently than if you simply use it less.

It is a popularly held belief that CFLs use a lot of energy to get started and it is better not to turn them off for short periods. The amount of energy varies between manufacturers and models—however, ENERGY STAR© rated bulbs are required to endure rapid cycling for five-minute intervals to ensure that they can hold up to frequent switching.

https://www.energy.gov/energysaver/save-electricity-and-fuel/lighting-choices-save-you-money/when-turn-your-lights

And then there is this:

enter image description here

Tate Britain, Martin Creed, Turner Prize in 2001 for Work No 227:

"The lights going on and off"

https://www.youtube.com/watch?v=zpDHQCmHltE

They appear to Fluorescent Tubes, but did those lights last?

I've heard you say in previous interviews that the point of the one without the lamp is to exhibit an artwork without an object in the space. Without the lamp, does the thinking behind it change? A little bit. Lights are objects. The reason why I used the lamps, in this case, has to do with problems with the lights. It had to do with technical problems when the lights go on and off, so we brought in another form of lighting.

enter image description here

From https://www.buro247.sg/culture/art-and-design/british-artist-martin-creed-explains-his-most-controversial-artworks.html

Improve this answer
4
  • 2
    Aren't "Starters" in fluorescent fixtures those little can shaped objects in the oldest of fluorescent fixtures? I've replaced a few and if I remember right, they were only a couple of bucks for 2 or 3. I do agree that starting up those old fixtures took a bit of power to heat up the electrodes (controlled by the starter) at the ends of the tubes for a few seconds, but I sincerely doubt it would be much of an expense, given the short duration for the start up.
    – George Anderson
    Commented Aug 4, 2021 at 21:09
  • 2
    One more thing: Old fluorescent fixtures are easy to repair, it's the bulb (tubes), ballast or starter. In my mom's house, she has beautiful, art deco style brass fluorescent fixtures, and one had died. From the 50's, they had ancient ballasts which had failed. I simply gutted it, replaced the ballast (before we had LED tubes), no more starter, converted from T-12 to T-8 bulbs, same headstone BTW, so a simple swap. I would have been a real shame to have to toss that beautiful old fixture.
    – George Anderson
    Commented Aug 4, 2021 at 21:14
  • 1
    @GeorgeAnderson sure, you have a valid counter point. I just went by what I remember, I have no first hand experience with comparative replacement & operating cost of these tubes. But the point is that what the OP's boss said could be based on outdated factors.
    – P2000
    Commented Aug 4, 2021 at 21:56
  • 2
    "Also, they used more power during start-up" even if they drew the full 3.7kW you can draw in most European houses it would hardly be noticeable since startup only takes about a second. That’s the same energy a 20W light uses every 3 minutes. Wear of the starter is really the main concern.
    – Michael
    Commented Aug 5, 2021 at 7:55
3

The answer to the narrow question asked is documentation exists that lamps burn for more hours with longer starts, but different fluorescent technologies (T8 instant start, rapid start T12, and preheat) all have different cathode technology and will result in different results, and even operating characteristics between different brands of ballasts will have different results.

Almost never considered is cost/savings of electricity, cost of labor to replace lamps, and cost of occ sensors and labor to install sensors. Really many variables exist and I've never seen a comprehensive study.

Improve this answer
1
  • 3
    Yes, this is a good point on the cost perspective. An electrician anecdotally told me that since the advent of LED, the cost of installing motion sensors in residential (small) spaces is not amortized/offset before the next reno.
    – P2000
    Commented Aug 4, 2021 at 18:39
3

While it's generally true that fluorescent tubes die of electrode failure, the efficacy of the phosphor degrades over the life of the tube too, so even though it may be good for many thousands of starts, after a few thousand hours of operation the tube's light output will be significantly less than when it was new. Leaving the light on continuously will result in faster degradation.

Improve this answer

Not the answer you're looking for? Browse other questions tagged or ask your own question.