Fluorescent Lighting

[Lenp]

Ok, here's a puzzler

A friend is making a rear illuminated sign and needed to install 3-20 watt strip type fluorescent fixtures. These were Cooper fixtures, purchased from Lowes. After wiring them, some would randomly light, and others would not light unless the lamp was touched (not moved). Swapping tubes showed the same random problem. I've run into fixtures that needed to be grounded so we added a ground. Same issue, but, if the power line was reversed the failure to light problem was less frequent. The magnetic ballast connections and wiring was checked and they were right. I increased the line voltage to 130V and no change. (I have run into ballasts used in microscope stage illumination that will not work 120 volts but will at 125!) We did find that if the fixture, is left powered it will eventually light, sometimes 10-15 seconds after the other fixtures.

So, is it the 'energy saving' green tubes, bad ballasts or bad Karma? He left with the sign, empty fixture boxes and the intent to run the fixtures for several hours to see if anything improves. If not he will return everything and and buy another product.

Side note!
Sadly the quality of many products is going down. These fixtures were really thin metal, with sharp edges and bad fitting sockets. The tubes were GE and you could see clear glass in spots where the coating was missed. This is what was common with off brand low end products I saw years ago. Recently I purchased some emergency lighting fixtures, made by Lithonia, the keyway slots for the junction box mounting are wrong. The fixture can only be mounted level on a octagon box if a washer is used under one screw. Lithonia is mum on the problem.
Really sad....
Len

[gerty]

The way I understand it, the back panel, the one that covers the ballast, must be grounded.
Maybe an issue of the paint not allowing that. The reason for that panel needing a ground is it helps the gasses ionize in the tube, much like the band around one of those U shaped strobe light tubes.
http://www.galls.com/style-BU087-genera ... le-strobes

I would scrape a little paint off, and use a jumper w/alligator clips to ground it, give it a shot.

[Lenp]

Thanks gerty,

The fixtures were grounded. 0.0 ohms.
The band on a strobe tube is a trigger band and it starts the tube's gas ionizing.

Len

[Dean Huster]

Try Philips tubes?

[Lenp]

Dean,
The GE tubes are what the big box store had, but that is a thought!
Thanks...

[dacflyer]

1st of all Cooper Lighting and Lithonia are both Junk.. i have nothing but bad luck with them,.especially the motion detection lighting.. Heath Zenith came out a winner with me..and also RAB lighting

anyway you might want to check to make sure you have the right bulbs for the fixture..
some are T12 and T8, my esp, is T8 will not always work in a T12 ballast.

and rapid start ballast are always problematic. if theres any dew or heavy moisture, the will not light..
only the ends of the bulb will light..and as you said..touch them, and they light up fine..
to solve that problem, i used some foil tape about 3/8" wide, and ran it the length on the tube. and this helped out a lot. ( put it on the back side of the tube so it does no block light. )

other option. get fixtures with electronic ballast. i have had no problems out of them yet, unless they just failed from old age..
only lights i had fail proof performance with was either pre-heat (starter type fixtures) still very popular in europe. or electronic ballast.
i am not a fan of rapid start ballast..usually inside of them its a cap failure, or shorted windings.

good luck..

oh, just for giggles...they say a rapid start ballast / fixture MUST BE GROUNDED... NOT!
i have a home made ( ballast mounted on a 2X4 and rigged lamp holders) fixture in a unheated shed. with exposure to humidity, and this fixture has never failed to light up.. the store bought fixtures fail every time the weather get moist... if interested, i'll submit a picture just request it.

[Lenp]

Follow UP
The owner ran the fixtures for 12 hours and they will now light every time. Sure looks like a lamp issue but if he is happy, I am elated!
Thanks everyone.
Len

[dacflyer]

another thing i have noticed with T8 Lamps is that many cheap brand do not burn in the tubes.
when i bought a case of 4ft and 8ft tubes.. they lit up on the ends, an gradually filled the tube as they got a few hrs of age on them.
not sure if its because they do not burn them in ( age the tubes ) or if its because they are trying to use less mercury. and so its harder for the little bit of mercury to ionize itself thru the lamp, til they can get the thinnest amount possible to light the lamp.

[Rodney]

I was highly skeptical but I tried a suggestion posted elswhere here in the forums. I bought a roll of aluminized tape (like used on duct work to seal seams) and cut some inch wide strips just a couple inches shorter than the florecent tube; glue them to the top of each tube (they are self adhesive) and replaced the lamps in their sockets. Viola!!!! they now light every time I throw the switch. I am pleasantly surprised.

[dacflyer]

yup, that's what i suggested...probably earlier in another related question in the forum
i had done this with the 8ft lamps in my shop that were effected but moisture in the air.
if its damp weather. they will not light..
ballast are good, fixtures are grounded etc..go figure:P

[haklesup]

so you just stuck the metallized tape to the bulb short of the ends. It did not make contact to anything like a floating plate capacitor kind of thing?

[Rodney]

so you just stuck the metallized tape to the bulb short of the ends. It did not make contact to anything like a floating plate capacitor kind of thing?

Correct, just short of the ends (do not touch the metal ends). It was a strip about 1 inch wide the full length of the top side of the bulb on each bulb in the fixture.

[haklesup]

you know, with a little packaging and marketing, precut strips like this could actually be a successful product. Sold as a flourescent tube starting booster you could sell millions of these in cold climates on the promise of more reliable starts and less frequent replacement (assuming it can make an old marginal bulb light a little longer). Remeber those cell phone booster patches. Nobody ever proved they worked in a technical way as far as I ever knew, at least this works.

Just sayin.............

[dacflyer]

its been working for me for over a year now..

i have not had to do this with electronic ballast tho,, just rapid start ballast - core-n-coil designs