I am having a problem with some T8's that I bought from HD.
They are Phillips Altos.
I have two boxes, of 10 one is daylight, one is for home and office (not
sure of K).
Anyway they keep burning out in 3 months. I have tried replacing the
ballast, I have tried other fixtures, I started dating them in marker on
They never are great, when they come on they are bright, but over a few
minutes they get darker and zebra lines (best way to describe the
pulsing) start appearing.
Any idea why this is happening? What would make one brand of tube
behave so poorly?
Hope we get some good answers to this Jeff, because I've had bad luck
with the T8's I get at the depot too. An election friend told me it may
be because they get turned on an off too much - they really prefer to
stay on for long periods of time.
They once advertised the life of fluorescent tubes as "xxxx hours,
less three hours per start" so apparently leaving them on is better
than turning them off when you go to lunch.
The alternative is to get LED replacement "tubes" and rewire the
fixtures *unless* they are electronic ballast. OK if you're the
electrician, expensive if you hire it done. The fixtures in my
basement are older T12 so would require rewiring. The LED tubes use
about half the power for the same number of lumens and they have a
predicted 50,000 hour life.
Example electronic ballast compatible tube here (it's a long URL so
watch for wrap on some newsreaders):
These are $9 per tube in single quantity (includes shipping). That
drops to $8 per tube if you buy 25 or more.
If you get 10 times the life of a fluorescent from the LED tube, then
you'd be way ahead on the total cost of the tubes.
I went with these in the 6 (4' x 4-tube) troffers I have in the shop.
The power/lumens is about the same as fluorescent tubes, but the light
stays bright as they age and that infernal buzzing is finally gone!
Since they direct light in only one direction (down) instead of 360
degrees, they seem brighter.
I just went ahead an bypassed my ballasts, no need to generate excess heat.
Sounds like the wrong kind of ballast. T8's need a T8 ballast,
and by that I mean a ballast for T8 only. The ballasts that
claim to work with both T8 and T12 bulbs generally don't work
well with T8s (this tends to directly correlate to the cost
of the ballast - there are good electronic ballasts, but the
cheap ones at HD/Lowes are a crapshoot).
I hate the T8 bulbs - the idiot that decided they should use
the same 2-pin base as T12s should be shot. I can't count
the number of cases I know of where T8 ballasts have been fried
by people putting T12 bulbs in, because they fit and there's
absolutely nothing on the fixture to say don't use them.
(to Mike's question, all flourescent bulbs don't like being
turned on & off, not just T8s. But the T8's seem much more
persnickety about the ballast they're used with).
Best advice thus far.
Where are the lights being used? Are they constantly turned on and off?
As John said, are you using the proper T8 only ballast? In addition to
ballasts, is it Instant start, rapid start or program start? The type
makes all the difference in the world depending on where it's used. In a
constant on/off environment, you want program start. If the lights stay
on throughout the day, you want instant start. Don't buy the cheap home
depot ballasts. Pay a little more for something like Philips Advance
Many of the new Alto bulbs offer and average of 40,000 hours but newer
Altos offer a 60,000 to 80,000 hour range but cost much more. Though,
all that is meaningless if you use the wrong ballast.
Let's see if I understand this. You hate T8 bulbs because idiots put
T12 bulbs in the fixtures? I like them because I can put in a T8
ballast when the old fixtures die and upgrade them.
In our shop we replaced all the fixtures with T8 in 2008. We are
starting to replace many of the bulbs as they are stating to die with
about 100,000 hours on them. They typically are turned on once a day
for 10 hours
Understand, I'm an engineer. I've spent 30 years designing
things to be as idiot-proof as possible, and one aspect of
that is, you don't use the same pinout for things unless they
are 100% compatible.
T8 and T12 bulbs are not interchangeable. Having the same
pinout is bad engineering, plain and simple.
BTW, changing the sockets when you change the ballast is
Round about that same time I replaced the couple of T8
fixtures I had with T12 ballasts. They're more reliable,
brighter, and last longer, and I figure by the time I'm
out of T12 bulbs LEDs will be cheap enough to be an
economical replacement (I use the same thinking with Edison
base bulbs - after trying a couple of twisties, I'm
sticking with incandescents until the LED prices are low
enough to make switching make sense).
A problem I've experienced with LEDs...
Late last fall I installed four, flush mount ceiling fixtures with integral
LED; i.e., the bulb was built in...when it burned out, toss the whole
fixture. Within about 4 months, two of the four started flickering; a very
annoying flicker, maybe 25 cycles or a bit less per second.
Web research told me that LEDs are very susceptible to voltage variation and
that a poor switch could cause the problem. Each flickering light had its
own switch; each was on a separate circuit. I figured my best bet was to
toss them and replace with incandescent. Which I just did.
These are all t8 ballasts. The shop has 3 bulb T8 dropped ceiling units,
(originally made for T8). The others have all been replaced with T8
Ballasts Ge Units. I had to rewire and jumper the tombestones for T8
and wire correctly.
Shunted tombestones are for 'instant start' ballasts only (never 'rapid-start').
From NEMA document available here:
Numerous ballast manufacturers have received and verified reports of incorrect applications of shunted
bi-pin lampholders (tombstones) used with rapid-start (RS), programmed start (PS) and dimming ballasts.
These incorrect applications have occurred in both new luminaires and field lamp and ballast retrofits.
For the purposes of this discussion, ballasts operating T8 rapid start lamps can be divided into two
classifications; rapid-start and instant-start.
Rapid-start, programmed rapid-start, and dimming models provide lamp cathode power
before striking the lamp (and sometimes after operation) and require that two wires be
connected between the ballast and each lampholder.
Instant-start ballasts do not preheat the lamp cathodes and need only one wire between
the ballast and each lampholder. Correct wiring of instant-start ballasts and rapid start
lamps necessitates that the lampholder terminals be shorted together, either via wiring
or the use of a shunted lamp holder.
There are two basic types of lampholders, normal (or non-shunted), and shunted. A normal lampholder
does not short or shunt the two lamp contacts within the lampholder, whereas a shunted lampholder
shorts the two lamp contacts within the lampholder. Other than possibly a manufacturerโs part number
that is stamped or molded into the lampholder, it is very difficult to identify whether the lampholder is
normal or shunted. These "shunted" lampholders were designed for instant start applications only.
Yep, The units required that. I thought I had chosen rapid start. But
found out Friday that they were instant start. Surprise, surprise. But
they are wired correctly.
When I looked up the model # of the ballast.
I don't know what the 3 bulb drop ceiling units in the basement are. I
didn't build them, just installed them.
The stripes have disappeared after the gases stabilized in a couple of
hours. New bulbs they told me (Philips) will do that.
At any rate they recommended I try other brands, which I have explained
I have, and they did work well. It's the phillips bulbs that are not
working well, and providing short life.
So, I think I've got to be tough and not take the easy way out while at
HD. I've got to either go to Lowe's or a supplier, or online.
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