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Blown Fluorescent Light

Blown Fluorescent Light

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Blown Fluorescent Light

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Filename:IMG_1083.JPG
Album name:mdcastle / Misc
Keywords:Lamps
File Size:391 KB
Date added:Jul 17, 2019
Dimensions:2464 x 1848 pixels
Displayed:173 times
Date Time:2019:07:17 12:45:25
DateTime Original:2019:07:17 12:45:25
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Jul 17, 2019 at 08:06 PM Author:
It was suffered from loss of vacuum!
mdcastle
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mdcastle 26956281@N02
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Jul 17, 2019 at 08:54 PM Author: mdcastle
This was on an instant start ballast. I went downstairs and noticed both tubes were out, so I figured it was a bad ballast. I shut the lights out for a while without investigating further or unplugging it. They next time I went downstairs I switched on the lights, and heard a pop and a flash and this happened to one of the tubes, but the other tube lit normally.
vintagefluorescent
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Jul 18, 2019 at 06:12 AM Author: vintagefluorescent
Was this tube a GE Mainlighter like the one on the left?
mdcastle
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mdcastle 26956281@N02
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Jul 18, 2019 at 09:35 AM Author: mdcastle
Yes it was, of the three cases of early 1970s mainlighters that my father saved, I have 14 left in service, one spare, and one I'm going to keep for my collection. They seem not to work well with the three instant start fixtures I have, they're underdriven and don't last long.
Lightingguy1994
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Aug 25, 2019 at 02:37 PM Author: Lightingguy1994
You should not be using these on instant start. You need F32T8 lamps or a magnetic F40 ballast for the mainlighters
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Aug 25, 2019 at 06:21 PM Author: bryanrb
Why cant the mainlighters be used on IS? Are you referring to the electronic ballasts as IS?
mdcastle
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mdcastle 26956281@N02
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Aug 25, 2019 at 07:17 PM Author: mdcastle
The fixture specifically said "For all 25, 32, and 40 watt 4 foot fluorescent lamps." I took that at face value.
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Aug 25, 2019 at 07:51 PM Author: bryanrb
It was then more likely that it was a defective lamp. The seal on the cathode likely failed since the lamp was old. I doubt the ballast had anything to do with it.
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Aug 25, 2019 at 07:51 PM Author: Lightingguy1994

Yes it was, of the three cases of early 1970s mainlighters that my father saved, I have 14 left in service, one spare, and one I'm going to keep for my collection. They seem not to work well with the three instant start fixtures I have, they're underdriven and don't last long.


It was mentioned in the above comment that they were being used on instant start. Not a good idea as noted, life will be short and thats not a good way to treat mainlighters considering how rare they are getting by the day. Instant start is usually those F32T8 ballasts with one wire to each socket
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Oct 13, 2019 at 11:37 AM Author: mdcastle
Are modern T8 lamps designed to be used by instant start ballasts in a way vintage lamps were not?

I put some lamps I didn't care about (current production Westy daylight tubes that I got someplace) and they ran fine, so I put the fixture back in service with 3500K Sylvania T8 lamps.

I'd really like to get a stash of 3500K T8 lamps from someplace, but most of the Craistlist and Facebook marketplace ads are for 4100K or 5000K or the seller doesn't note.
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Oct 13, 2019 at 12:34 PM Author: don93s
It's possible that modern filaments in F32T8 are better designed for IS than older T12's. More than that, there are many variations between lamps over the years in the filament/emitter construction. Some won't tolerate IS for very long, while others seem just fine. IS starts the lamp from a cold electrode which is the most stressful until it transitions to 'hot cathode' temperature. Under-driven F40 on IS might be the worst...especially if there are frequent starts.
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Oct 13, 2019 at 08:19 PM Author: Lightingguy1994
Yes T8 lamps are designed for instant start, you can expect up to 20000 hours lamp life for a T8 on IS. The life of T8 would be longer on rapid start reaching the 30000 hours on good lamps no problem.

F40T12 needs the filaments to be heated before starting to prevent the emissive coating from being blasted off by the ionized gases. Older lamps like mainlighters were designed for rapid start or preheat. If used on instant start the filaments dont get heated so the sudden rush of ionized gas hitting them blasts off the emitter and will grow that black sock on the end of the lamp in no time.

This is why slimline lamps don't last that long and usually have a life of around 7500 - 9000 hours.

3500K T8 have a really nice colour youll like them when you get some. Have a look on light bulb sites like 1000bulbs
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Oct 13, 2019 at 08:23 PM Author: Lightingguy1994
Is the fixture in this picture the one you are refering to as instant start? I have a fixture like this and its got a ballast built into the end and it does actually heat the electrodes but not as good as a real brick ballast
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Oct 13, 2019 at 08:47 PM Author: mdcastle
I did buy a few packs of new 835 Sylvania tubes (all they had) when Fleet Farm was closing them out and do like the color. My kitchen light gets switched on several dozen times a day; I swapped out the instant start ballast there with a programmed start but the basement lights don't get used as much and the ballast is embedded with the fixture.

I don't see the collectability of fluorescent tubes- not now and especially not when I bought the instant start fixtures. To me the mainlighters were just something I had laying around that lit up. But on the other hand I don't want to abuse any lamp so would not have used them in the instant start fixtures had I known it was a bad idea. The fixture said basically "put in any four foot lamp". I did eventually notice they were burning out faster in the instant start fixtures than my rapid start fixtures, but assumed that would be true for any lamp. I have enough T8 tubes I can save the remaining Mainlighters for the rapid start fixtures.
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Oct 13, 2019 at 08:54 PM Author: Lightingguy1994
The programmed start ballast is very good for the T8s, youll get the most out of them for sure. The mainlighters and others made back in the day are excellent tubes, they just dont make them today like they used to
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