how long do shop light fixtures last?

[tjg911]

i have used my shop lights with their original tubes starting in april 2004. I have just completed my 6th season using them.



i bought 4 inexpensive ($7.50) home depot 4' t8 fixtures and tubes, 1 cool white and 1 soft white per fixture. i run them from early march thru the 3rd week in may for 16 hours a day then they do not get used again until the following march. the following year a friend built the same stand, bought the same fixtures, used them for 2 years then i got all 4 with tubes. his are backup i never used until about a month ago.


my question is are these cheap fixtures good for 6 years of use (from early march thru late may about 90 days having them on for 16 hours per day)? read my problems below.


about a month ago i started to have trouble with 1 of my shop lights. i swooped tubes but the fixture was still a problem and now the same thing is happening to a 2nd fixture again 1 of my 4 original fixtures. i assumed the 1st fixture was bad and tossed it.


today i come home and 1 fixture is out. if i wiggle the tubes sometimes i get one or both tubes to light. i have taken the fixture down to swoop tubes or work on the work bench but when i rehang it one of the lights go out. if both are on they'll go out in a short time, not sure how long but maybe 10 minutes. i had this fixture down and up 3 times with the original tubes and new tubes but it will run then shut off or 1 tube will go out. so i tried another fixture (one of my friends with 1/3 the usage on it 2 years use, same 90 days 16 hours per day on) with basically similar results. so now i'm not sure why a fixture with just 2 years use is acting the same as a fixture with 6 years use. i've tried my tubes and his same results. can't get both tubes to go on and stay on.
so i finally rehung my fixture after working on this for over an hour and it's been on for about 90 minutes. i'd bet a $100 that if i raise or lower the chains one or both tubes will go out. i only need to use this for a couple of clody rainy days but there is next year.... i just went back down and in the time it took to post this both tubes are off!


are these home depot shop lights worn out at 6 years (doesn't explain why the fixture with 2 years is acting up)?


i can't run down stairs every 1/2 hour to see if the fixture is on and especially next season.


any ideas would be appreciated. i hate to throw away a fixture that is not faulty but even a newer fixture is acting up. i'm lost.


tom

[dice]

It could be flaky electronics in the ballasts that did not hold up,
but the way they go on and off it sounds more like dirty
contacts, corroded by moisture maybe.

Try sandpapering the contacts on the ends of the tubes, and
maybe spray a little contact cleaner into the connectors in
the light fixture (getting at those to clean off corrosion is likely
to take some specialized tool that you would have to invent;
some kind of contact enhancer, a conductive grease on the
contacts on the bulbs, might work better).

I have had them go out where a little twist of the bulb would fix
it. I also have two year old cheap HD fixtures, still working so
far.

Note that the bulbs do lose light intensity on their own over
time:
http://www.bchydro.com/powersmart/te...with_time.html

[dcarch]

Like Dice said.

Also:
Most fixtures use electronic ballasts. They either work or they are dead.

However, some electronics might be temperature sensitive and some fluorescent tubes don't work well in cold temperature.

dcarch

[ContainerTed]

A safety reminder - always unplug anything electrical before attempting repair.

Intermittent problems are usually caused by some leve of oxidation within connections. After that, the next most likely cause would be failure of a semiconductor device - usually when heat is generated. Like already suggested here, the contact ends of the light bulbs should be burnished a little bit to get rid of any oxidation. Any super-fine grit can be used - preferably above 400 grit. In the past, I have even used a tiny bit of baking soda to provide the needed abrasion. Don't use things which leave a "coating" as many of them either break down or form unwanted compounds when subjected to heat and/or voltage.

I keep some 800 grit garnet dust "crocus cloth" that I've had for decades. We used it on 50 caliber machine gun barrels on B-52's back in the 60's.

As for those contacts that are difficult to get to, if you're convinced that a bad or intermittent connection IS the problem, put a small bit of emory paper or fine grit wet/dry sandpaper on a pencil or skewer and give the target a few strokes.

Most of us old electronic bench techs have a few hemostats of different angles. Medical folks also have good access to these wonderful instruments.

Many times, a very thin layer of oxidation will simply degrade the connection enough that the circuit malfuntions due to a very small reduction of the voltage level. Florescent lights and their ballasts are somewhat sensitive to this condition. My years of working on the B-52, KC-135, and F-111 aircraft taught me that all connections (even gold plated) will need to be "cycled" after a while (unplugged and plugged). I learned that even in the best of environments, all connections will develop some oxidation layers.

So, the bottom line is just like you do when you're soldering those copper water pipes (sweat the joints), first ya gotta SHINE them surfaces.

Be careful.

Ted

[dice]

Pencil erasers themselves usually work well for cleaning contacts.

I have done that a lot with computer parts that plug into a slot
inside a computer and have a flat blade type of contact (ram
modules, peripheral adapter and network cards, etc). It works
well. I usually keep a paper pad beside me to clean off the
eraser every so often as corrosion from the contacts builds up
on it.

Stabilant 22 may be overkill for an application like flourescent
light contacts, but a lot of technical personnel would not give
it up for anything:

http://www.stabilant.com/techt02h.htm

(Not cheap:
http://www.micro-tools.com/store/ite...px?itemCode=22
)

[Amigatec]

I think the problem is with the cheap fixtures. I bought 5 of these lights from Walmart, one lasted about 8 hours, and a second one is acting up this year. It had just one season on it before acting up, I have seen those lights discussed of other sites and many people report the same problems. I think 6 years is really good for these. At $7.50 per light you can't expect much.

[rsg2001]

I change the grow lights every two or three years. This year, I changed them all out, and I found a huge difference in the robustness of my seedlings.

[ContainerTed]

Originally Posted by Amigatec

I think the problem is with the cheap fixtures.

I think 6 years is really good for these. At $7.50 per light you can't expect much.

Short of free, I did a lot of looking and found that Lowes has a 4 foot, two bulb, T-12 fixture for $9. It doesn't come with bulbs. But, they have a box of 10 bulbs (T-12, 6400K Daylight) for $20. So, three fixtures and a box of bulbs (with spares) for $50 seemed to be cheap (if you can't find free). If you can find one of their 10% off cards, the bargain gets even better.

Ted

[dice]

From a post dcarch made a couple of years ago, the cheapest
Walmart fixtures were notoriously bad (fire hazard).

These HD fixtures that I have were around $10-12 each.

[evan1]

I have the same fixtures and have experienced the same result- mine from 2003. I threw out two this year and got new ones- sometimes they worked, sometimes they didn't.