32T8 Lamps Flash Brightly Seconds after Power Disconnected

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Tommy Hobbs

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I removed a quantity of 8-2X4 4 lamp (T12) 120V lay in fixtures and installed
8 new fixtures with electronic ballasts & 32T8 lamps, 1-4 lamp ballast per fixture, 4 lamps per fixture, my problem is turn switch on everything is fine, turn switch off & then after 2 > 3 seconds all fixtures flash real bright then go off and stay off until switch turned back on, then starts all over again, anyone know anything about this. Appreciate your help
 
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ty

Senior Member
Location
3rd Rock from the Sun
We just relamped an office last week and changed ballasts where needed.
T8 4lamp lay in fixtures.

There were 12 on one switched section. Nothing like you describe happened.

We were using smart ballasts on 277v.

Are your ballasts rated for the voltage applied?
 
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Tommy Hobbs

Member
I have checked all wiring connections, phase, Neutral, Grounding, etc.
Voltage is 121V leaving switch to fixtures, when switch is turned to off position, voltage is immediately cleared, then like I stated 2>3 seconds later all lights flash brightly, existing wiring but have checked from the panel to switch to all fixtures, can find nothing wrong, flash reminds me of a camera flash, strobe, like it is discharging
 
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Tommy Hobbs

Member
hunt, concerning the switch, i have replaced it but the same thing happened then removed switch touched wires together, let on for a few minutes, pulled wires apart, same thing all over

ty, yes the ballasts are rated for 120v, have 121v at switch, panel or fixtures
 
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RETRAINDAILY

Senior Member
Location
PHX, arizona
I would bring it to my suppliers attention he should be able to get some answers from the manufacture.
If not, he knows there is a oddity in case you have to take theme back.

That would blow the profit margin !
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100122-1435

Tommy Hobbs:

I suggest it is a quirk of the ballast, and from a customer point of view a design defect.

An electronic ballast will have a rectifier and filter capacitor from the input supply to generate DC. From the DC a high frequency AC signal is generated. Above the audio range, but not too high. Possibly 25 to 30 kHz. The capacitor in the ballast apparently stores energy beyond the time you remove the input AC.

If upon removing AC power the lamp immediately turns off, then after 2 seconds flashes, it would mean that residual energy was in the capacitor and after the 2 second delay the capacitor voltage dropped to a point where there was still a substantial amount of energy, enough to cause a bright flash, and at this voltage point the electronics has a weird characteristic to dump the energy into the lamp.

Same type of occurrence but the lamp remains at about normal intensity after the power is removed for the 2 seconds, then does its flash thing.

A defective ballast in manufacture or design.

.
 
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Tommy Hobbs

Member
I have gotten with tech. support with advance ballasts & was told that this could be a problem with 1 or more ballast(s) storing up energy & then discharging, he said that he has never seen or heard of this but is without a doubt possible, he also said that the lamps could also possibly be causing this AS they could also be storing up energy ????
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100122-2019 EST

The lamps can not store very much energy. The stored energy would be the capacitance across the lamp and this is very small. The amount of this energy is so small it could not light the lamp.

You also have to understand the characteristics of a fluorescent tube. It is a gaseous discharge device. It has a breakdown voltage value, a negative resistance characteristic in a portion of its conduction curve, and an approximately constant voltage characteristic at higher currents.

The problem is in the ballast.

.
 
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rt66electric

Senior Member
Location
Oklahoma
check your piping and switch legs

check your piping and switch legs

Check your piping and switch leg routing.make sure the power and switch leg in in the same conduit?? I had a bizzare problem the ultimate reason was that it was a 6 bank switch box w/two conduits, one in and one out. The power wires came in one conduit and the switchlleg out of the other. I believe the correct term is called hyteresis (sp). A transformer is made out of 1/2 conduit and 12 ga wire. Moved the power and switchleg into the same conduit and the problem went away.
 
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boboelectric

Senior Member
Location
Eighty Four,Pa.15330
Tommy Hobbs said:
I have gotten with tech. support with advance ballasts & was told that this could be a problem with 1 or more ballast(s) storing up energy & then discharging, he said that he has never seen or heard of this but is without a doubt possible, he also said that the lamps could also possibly be causing this AS they could also be storing up energy ????[/QUOTe



My shop lights do this once and a while. Spooky!
Click to expand...
 
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Tommy Hobbs

Member
(1) I can understand the ballast(s) causing this
(2) I could not see the lamps causing this
(3) There is only 1 conduit and power, switchleg & ground, all in it
(4) I will try to check out monday and let you all no the results
(5) Thanks for everyone's help
 
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ahp691

Member
Location
Connecticut
I had CFL bulbs do the same thing

I had CFL bulbs do the same thing

We wired a new house. the customer put in CFls through out the house. I got a call back that the two up stairs hall lights flash when the light switchs are turned off. It was wierd. I witnessed these 13 watt CFLs flash about every 30 seconds. just bright enough to see even with the shades on. What we found, I checked the with a volt meter if we could see a spike. My digital meter couldn't pick it up. ( I wish I had an annalog meter) We then checked our grounds and neutral connections in the panel, boxes, and meter socket. I suspected there may have been a ground issue with the pad mounted transformer. This was the first house in the subdivision. We then pulled our neutrals and grounds off the bus bar in the panel for this circuit to check for continuity between them. I found something there, (in the 14-3 between the 3-ways) not a clear connection. So we replaced this wire. The problem still existed. we also checked the low quality big box store chinese fixtures the builder supplied they were ok. So the problem still existed. We tried diffrent CFLs and no longer had the problem.
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100130-0743 EST

ahp691:

Your post probably belongs in the thread LIGHTING, CFL flicker with switch off.

The problem you describe is a result of leakage current. Could be capacitive coupling. That you eliminated the flashing by changing to a different manufacturer is important information. This correlates with my experience and what others have reported.

The problem with the CFL is quite different than the problem described at the beginning of this thread.

You might put an entry in the LIGHTING thread indicating that by changing to a different manufacturer that you eliminated the problem. Names of the different manufacturers are important. NuVision flashed for me and GE did not, but these were manufactured in different years.

.
 
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Tommy Hobbs

Member
I did make it back to check out, what I found was when a certain fixture was disconnected, the bright flahing of the lights would disappear, changed out the ballast with a new one, no more problem, sorry it took me so long to check this out, resolve and to let everyone know what was found, also thanks to everyone who replied
 
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