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One lamp failure on series ballast?

One lamp failure on series ballast?

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This is a lensless troffer in an antique mall, one of hundreds that are still magnetically ballasted T12. Lamps are mostly Philips CW Supreme now, but an older lamp that has failed on the ballast controlling the inner lamps apparently conducts enough that the other lamp on the ballast still operates at full brightness. It is definitely a magnetic rapid-start ballast, but I am wondering why the other lamp is not glowing dimly and striating like the failed lamp.

Acorn_streetlight_change_1940s.jpg Last_Tacoma_Series-Lit+.JPG 4-lamp_1_lamp_failure+.JPG TL865s+.JPG

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Filename:4-lamp_1_lamp_failure+.JPG
Album name:arcblue / Lighting in Washington State
Keywords:Lamps
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Date added:Mar 23, 2016
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nicksfans
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Down with lamp bans!


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Mar 23, 2016 at 01:20 PM Author: nicksfans
I've seen this happen where it was actually a problem with the ballast, not the lamp (installing a known good lamp didn't change anything). In one case, the ballast was overheating and tripping the thermal protection, so the one lamp that actually lit would cycle on and off throughout the day.

I like my lamps thick, my ballasts heavy, and my fixtures tough.

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veryhighonoutput
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Mar 23, 2016 at 01:23 PM Author: veryhighonoutput
I've seen these situations either the bulb still conductive or the ballast is confused and needs to reset wish you could take bulb out

T12/ t17 there's a reason they made heavy magnetic ballasts

Lightingguy1994
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Mar 23, 2016 at 01:30 PM Author: Lightingguy1994
Its possible that the lamp is fully mercury starved. I have a fully mercury starved F40T12/D Ecolux that still lets the other lamp work fine on a series ballast. In a 4 lamp setup it looks as if the mercury starved isn't lit at all
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Mar 23, 2016 at 02:10 PM Author: DetroitTwoStroke
I saw this happen to a couple of fixtures in high school. I saw some where new lamps fixed the problem, and some where only one tube would light and the working lamp would remain lit even after removing the unlit tube - must have been a short inside the ballast. Those were rare, though - I only remember seeing it a couple times.

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Mar 23, 2016 at 05:42 PM Author: don93s
I have a 2x40w RS at work with only one lamp currently lit....the other, a Sylvania F40/D50 is completely mercury starved. I watched it dim over a period of a few weeks. There are other cases where the starting capacitor shorts out sending the OCV directly to the starting side lamp which usually leads to over-current and over-heating of ballast.
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Mar 23, 2016 at 07:21 PM Author: RCM442
I've seen some fully mercury starved F96T12s before, no glow at all, but hot to the touch so it was fully conductive and working. Just no mercury to make it light! Almost like one of those dummy tubes.

Linear fluorescent will never lose to LED!
I am not Anti-LED, as I have some in use at my house.
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Mar 24, 2016 at 03:03 AM Author: veryhighonoutput
Oh yeah the fantom bulb! I know where one is I need to take a pic its the coolest bulb ever even though doesn't do anything

T12/ t17 there's a reason they made heavy magnetic ballasts

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Mar 24, 2016 at 03:37 AM Author: dor123
@RCM442: What you describing, looks more like a lamp that lost vaccum but that still conducting.

I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the European date format (dd.mm.yyyy).

I lives in Israel, which is a 230-240V, 50hz country.

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Mar 24, 2016 at 04:28 AM Author: Ash
That is not possible. Air is isolator. The quantity of air it takes to make the lamp not start at all is fairly small, less than it would take to dim it down to this level

If it is a ballast failure, it would be a short across one lamp. If one lamp is at Neutral potential on one end, then maybe a short from the other end to the lantern casing (so shorting the lamp), either inside the ballast or damaged wires in the lantern

I too seen Mercury starved lamps to the point that they are not visibly lighting when they are next to a good lamp. You could tell the lamp is working by touching it and seeing that it is hot along its entire length, not just near the electrodes
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Mar 24, 2016 at 05:01 AM Author: veryhighonoutput
Yes true if lost all vacuum due to violent burn out ballast over heats and will react like this sometimes turning on and off on its own. in this case that bulb out doesn't look to bad I bet it's just mercury starved

T12/ t17 there's a reason they made heavy magnetic ballasts

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Mar 24, 2016 at 05:25 AM Author: dor123
Globe Collector commented in the past to some users that uploaded pictures of pinked or redded out fluorescents, that they aren't mercury starved, but air poisoned (= Got impurities or partially lost vaccum). There are several posts here. You can search "Air poison" or "Air poisoned" in the site to look at his comment.

I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the European date format (dd.mm.yyyy).

I lives in Israel, which is a 230-240V, 50hz country.

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Mar 24, 2016 at 06:13 AM Author: Ash
The quantity of air in "air poisoned" lamp is tiny, and the light is still well visible. Anything more and the lamp would simply not start
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Mar 24, 2016 at 07:23 AM Author: veryhighonoutput
Ah yes air poisoned makes sense

T12/ t17 there's a reason they made heavy magnetic ballasts

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Mar 24, 2016 at 07:37 AM Author: Ash
No it does not. There is no quantity of air such that will dim the lamp down to 0 but still let it conduct. In tiny quantity it will change the color/brightness, but the presence of air makes the voltage higher. Any more air and the voltage required will be more than the ballast supplies, so the lamp won't start at all
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Mar 24, 2016 at 09:01 AM Author: RCM442
@Everyone, this is not an air poisoned lamp, if it was like Ash said, it would still light a little bit. The only exception to this is if the lamp has lost vacuum or leaked. If the lamp is still hot to the touch it means it's running but mercury starved, T12s just get dimmer and dimmer when they go starved. T8s go dim pinkinsh-red. If arcblue is able to touch the lamp and see if it's hot, we will know it's starved. If it's not hot, it's a ballast failure.

Linear fluorescent will never lose to LED!
I am not Anti-LED, as I have some in use at my house.
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Mar 24, 2016 at 09:33 AM Author: veryhighonoutput
Only way is pull that bulb out. I still think it's conducive just enough whether it's poisoned or starved, the ends aren't that black, the phosphorus still in tacked

T12/ t17 there's a reason they made heavy magnetic ballasts

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Mar 24, 2016 at 09:49 AM Author: rjluna2
Here is an example I have this General Electric Helical 26 Watts CFL that has been dimmed, but the tube itself is hot. Comments?

Pretty, please no more Chinese failure.

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Mar 24, 2016 at 10:50 AM Author: Alights
Can't be air poisoning magnetic RS ballasts can barely start lamps as it is (OCV just enough ) I've come across merc starved lamps that are out shined by working lamps and ballasts can fail like this .if the cap is degraded I suppose the ballast wouldn't overheat due to lower lamp current
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Mar 24, 2016 at 11:37 AM Author: Ash
If it is conducting without light it is starved

The voltage it takes to start or hold arc across a distance in gas depends on gas type and pressure

Gas type - there are gases that are fairly good at conducting discharge - the noble gases Argon, Xenon.... that are used as buffer in lamps. There are gases that are bad - Nitrogen. There are gases where it is hard to start any discharge - SF6 this one is used as fill in high voltage switches to prevent arcing

Pressure - the lower the pressure, the less voltage is refor arc between electrodes at existing distance



Normal lamp have the Argon buffer and Mercury vapor at low pressure. Discharge can start and keep going in it under very low voltages - 230V are sufficient to start a cold discharge across 4ft distance. 1KV is sufficient to get a mass ionization. 100V are sufficient to keep the hot discharge going across 4ft distance

Mercury starved lamp is the same but without the Mercury. There is only the fill gas, under low pressure. It will conduct by itself at low voltages - Maybe lower than normal lamp. But wihtout the Mercury there is no much usefull light (including UV for the Phosphor) from the discharge

Air poisoned lamp got some additional gases in it. In very low concentrations, they affect the color and such. But The more air there is, the voltage it'd take to start or keep an arc in it rises dramatically. It is not long before the voltage it'd take is more than the ballast puts out - If the lamp would start it would still emit visible light, but it is not starting. The voltage rises for 2 reasons :

- Air is 4/5ths Nitrogen, that is good isolator. It takes higher voltage to arc in Nitrogen

- The pressure in a normal lamp is well below atmosphere pressure. Any contamination from the outside means more gases getting in, so higher pressure and higher voltage

So there is a "step" between 2 conditions the lamp can be in : Either very little poisoning so the color and light changes but is still visible, or higher posioning that prevents the lamp from starting. There is no amount of poisoning such that would make no light but still let the lamp conduct
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Mar 24, 2016 at 12:32 PM Author: hannahs lights
What are dummy tubes?? What would be the point t of something that don't light up? I never heard of these before maybe someone can explain p!ease. Second yes I think that tube is probably mercury starved its fitting mate next to it is almost certainly running at nearly full power
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Mar 24, 2016 at 01:59 PM Author: arcblue
Mercury-starved was my guess, but I'm used to the tubes glowing pink when they are operating in an argon-only discharge. Maybe this tube was getting close but still had a little mercury. I probably could've reached it and felt if it were hot but I was more fascinated with the sink faucet turning on by itself. It was NOT on a motion sensor and it turned off again when I started washing my hands. So, lacking an explanation for this, perhaps supernatural forces were messing with the light fixture as well.

Hannah, this is an example of a 'dummy' tube. They are only for series-wired rapid-start ballasts as normally removing one lamp will keep the other from lighting, so the shunt tube maintains conductance for one-lamp operation.

I'm lampin...

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Mar 25, 2016 at 11:18 AM Author: hannahs lights
Thank-you for that I've never seen or heard of dummy tubes before it's a new one on me. At least know il no one if I ever see it in real life.
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Mar 25, 2016 at 11:40 AM Author: Ash
You are unlikely to. This lamp is intended to work in 2x40W or 2x34W series setup, as in 2 lamp Rapid Start ballast. There are no such systems in use in the 230/240V 50Hz hemisphere, atleast if there are then very rare - That would never justify sales of such shorting lamps
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Apr 01, 2016 at 10:38 AM Author: veryhighonoutput
Did they replace the bulb yet?

T12/ t17 there's a reason they made heavy magnetic ballasts

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May 29, 2017 at 05:40 PM Author: streetlight98
I have a Value Bright F20/CW like this. Next to a lit lamp, it looks like its out but there's a faint glow like you can see in this tube. I suppose Value Dim would be a better brand name for it lol.

Please check out my newly-updated website! McCann Lighting Company is where my street light collection is displayed in detail.

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May 29, 2017 at 05:41 PM Author: Cal
Don't these fixtures allow for a failed lamp by having caps that act as a shunt in the case of one of the lamps failing? I'm sure I read that somewhere on here, but I admit I know next to nothing about US fixtures. If it is the case, it could just be a failed lamp.
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May 29, 2017 at 05:59 PM Author: streetlight98
No. The lamps are in series; when one lamp is removed, the second goes out. If the remaining lamp is the first lamp in the series, it will glow dimly but if the first lamp is removed the second one will be out cold. Kind of annoying, especially when a small room is only lit by one two-lamp fixture (since there is no redundancy) but I suppose it calls for quicker maintenance compared to having all the lamps in parallel, since with that scenario, maintenance tends to turn a blind eye until the whole fixture is out anyway. That's why for small rooms with no windows I would try to use two fixtures or use a three-lamp or four-lamp fixture, so they're on two separate ballasts (could use a 2-lamper with two single lamp ballasts but that's not a common thing; I'd imagine any out there are custom). One thing I HATE are newer programmed start T8 4-lamp ballasts that drive all four lamps in series. What a NIGHTMARE lol. But it ensures the fixture gets all new lamps instead of simply plucking out the dead ones, which is usually what I do lol.

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Jun 05, 2017 at 04:10 AM Author: veryhighonoutput
A there lamp fixture would be perfect especially if it had a single f40 ballast in the middle, Those are the most reliable

T12/ t17 there's a reason they made heavy magnetic ballasts

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