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carpenterty 12-02-2010 03:46 AM

Fluorescent lights multiple
I purchased 10 fluorescent lights from Home Depot today and installed them this evening. All lights are wired in parallel white to white black to black and ground, switch is on the black hot. The wire guage is 14-2 on a 15 amp circuit. 5 of the 10 illuminate the other 5 will start to illuminate turn bright at ends of the fluorescent tube and go out, this is very brief. When I turn the switch off the remaining 5 that were illuminated will turn off as expected but the 5 that were originally out will have a quick short dim flicker starting closest to the switch and continue down the line. The lights are arranged with two 4ft lights together making an 8 ft run then every other rafter another pair totaling 5 runs.

Any ideas why these wont illuminate? Could all 5 of the ballasts be faulty? These are the T-12 4ft Home depot lights that sell for$ 20 a piece. Also the lights that will not illuminate are random not just one side. Some are on one side or the other others are both pairs. To check if it was my wiring I disconnected a light and hooked it up to an extension cord I had cut I then plugged it into an outlet and again just briefly flickered.

If any one has any ideas that would be great otherwise im taking them down and exchanging them at the Depot.


Just Bill 12-02-2010 05:59 AM

I would suspect a poor connection in the string. OR, the label on the box that says "made in China".

oberkc 12-02-2010 06:33 AM

I would be measuring voltage at the connection of each light, starting with the first suspect unit. See if you have 120V. If not, you have probably confirmed the first theory of Just Bill. Check the voltage while the lights are hooked up and operating as much as possible. If you must remove lamps to test voltage, do it one fixture at a time.

I consider it unlikely that you have this many faulty lights. I am also sure that it would be frustrating to remove and replace them, only to find the same problem.

AllanJ 12-02-2010 06:46 AM

Remove the lamps from the fixtures. Then put the lamps back in one fixture. Try a few combinations. I would be mighty surprised if the fixtures behave differently depending on which other fixtures are operating.

Measuring the voltage at the sockets at each end of the lamp may or may not give 120 volts.

I would believe that some of the fixtures are defective, or might have been multi-voltage fixtures wired for the wrong voltage for the wrong export country internally (China uses 240 volts).

oberkc 12-02-2010 07:59 AM


Measuring the voltage at the sockets at each end of the lamp may or may not give 120 volts

In case it was unclear from my post, the measurements should be where the supply is connected to the fixture, not at the lamp sockets. My only concern about removing lamps was the possibility that the connections were made inside the fixture housing and inaccessible without first removing the lamps.

carpenterty 12-02-2010 11:16 PM

UPDATE..... I checked each line for voltage and as I suspected power was present. As I mentioned before I had hooked up the light to a cut extension cord and plugged it in to verify the light was in fact defective.

I returned the 5 lights to Home Depot and purchased 5 more from Lowes which was a different brand and I didn't like my odds with Home Depots brand being 5 out of. 8 were deffective (I had two fixtures prior to my last purchase)

So all 10 lights are all working perfectly! I never would have thought there could be that many defective ballasts in brand new lights!!!Thank you all for the prompt suggestions!

LyonsElecSupply 12-02-2010 11:18 PM

You get what you pay for. Do it right the first time and you wont have to duplicate effort.....

Sorry about your bum luck.

bobelectric 12-03-2010 04:08 AM

Electronic ballasts ,I suppose?

carpenterty 12-03-2010 04:11 AM

Yep electronic ballast!

bobelectric 12-03-2010 04:16 AM

They always make me look bad.Especially 40 watt g11 ballasts used in malls.

czars 12-03-2010 07:48 PM

Make sure that your ground wires in your power cables are connected well to each fixture. Many of the new electronic ballasts must have a capacitive coupling between components within the ballast to ground (grounder fixture) in order to start the lamps. If the fixtures are not connected to ground, the lamps will not start.

carpenterty 12-03-2010 07:58 PM

Yep all ground wires are bundled together and attatched to the fixture ground lugs. I have had problems with old lights that when not grounded would not completely light and would dimly glow when the switch was off. But these new fixtures do illluminate when not grounded.

The problem was buying a mass produced china made light!

emolatur 12-03-2010 09:11 PM

re the grounds, it's not just the new electronic ones. Some of the crappier magnetic ballasts misbehaved in similar ways.

frenchelectrican 12-03-2010 11:26 PM

Normally I don't use any flourscent luminaire from big box store unless it is a last resort due they made pretty cheap and most of the flourscent luminaires are not super bright due they are used as resdential useage not like true commercal / industrial luminaires they are better quanity due better ballast and good set up.

But instering twist most resdentail ballast are set at 0.60 BF { Ballast factor } the other terms mean brightness compared to true commercal ballast they typically run 0.80 or so depending on which ballast I use.


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