# Do fluorescent lights need a ground in order to work?



## HARRY304E (Sep 15, 2010)

black said:


> If so, why? Forgive me if this is a stupid apprentice question. I was told that they do, but I remember holding a fluorescent bulb up to a van der Graf generator in school as a kid, and the bulb lit. That bulb wasn't in a fixture, of course, so I'm guessing this is part of the difference. I cant find a clear answer to this elsewhere online. Thanks.


Yes they do.


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## A Little Short (Nov 11, 2010)

Actually, the ballast is what needs a ground.


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## Shockdoc (Mar 4, 2010)

It was the older magnetic ballast that required a ground. the new electronic fixtures will work fine without one.


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## Big John (May 23, 2010)

I've seen more than once where a hard-starting fluorescent fixture would come on instantly when you touched it. Apparently grounding the reflector changed the capacitance in the lamp and allowed the gas inside it to ionize more easily. I don't understand what makes that true.

It either happens when the fixture was properly grounded, or happened when you grounded the fixture through your body.

-John


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## wcord (Jan 23, 2011)

Didn't the ballast have some internal wiring to ground that was part of the ignitor? 
I remember that we had problems when GFCI receptacles came out. If they were connected so the lighting was protected, every time there was a fluorescent in the circuit, the plug tripped as soon as the switch was flipped


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## RePhase277 (Feb 5, 2008)

I have seen lots of fluorescent lights and hardware that specifically stated that the lamps be installed within 1/4" of the grounded reflector. Like John, I have seen many lamps pop to life when I touched them.

Seems that under certain conditions fluorescent tubes are hard to start unless near a grounded object.


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## BBQ (Nov 16, 2010)

Big John said:


> I've seen more than once where a hard-starting fluorescent fixture would come on instantly when you touched it. Apparently grounding the reflector changed the capacitance in the lamp and allowed the gas inside it to ionize more easily. I don't understand what makes that true.
> 
> It either happens when the fixture was properly grounded, or happened when you grounded the fixture through your body.
> 
> -John


Bingo

Many ballasts state the lamps must be mounted withing 1" of a grounded metal reflector.


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## Shockdoc (Mar 4, 2010)

InPhase277 said:


> I have seen lots of fluorescent lights and hardware that specifically stated that the lamps be installed within 1/4" of the grounded reflector. Like John, I have seen many lamps pop to life when I touched them.
> 
> Seems that under certain conditions fluorescent tubes are hard to start unless near a grounded object.


The biggest problematic fixtures I have ever dealt with like that are the 2x2 U lamp fixtures.


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## TOOL_5150 (Aug 27, 2007)

Shockdoc said:


> It was the older magnetic ballast that required a ground. the new electronic fixtures will work fine without one.


late last year I did a building retrofit from T12 to T8 in san francisco. the building is wired in K&T. I can guarantee newer ballasts work just fine with NO ground.


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## HARRY304E (Sep 15, 2010)

Big John said:


> I've seen more than once where a hard-starting fluorescent fixture would come on instantly when you touched it. Apparently grounding the reflector changed the capacitance in the lamp and allowed the gas inside it to ionize more easily. I don't understand what makes that true.
> 
> It either happens when the fixture was properly grounded, or happened when you grounded the fixture through your body.
> 
> -John


It has something to do with a static electron charge that goes through the reflector to ground something like that.:blink::laughing:


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## black (Oct 12, 2011)

Thanks all


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## Semi-Ret Electrician (Nov 10, 2011)

HARRY304E said:


> Yes they do.


or standing in front of a radar antenna


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## Big John (May 23, 2010)

black said:


> ...But I remember holding a fluorescent bulb up to a van der Graf generator in school as a kid, and the bulb lit....


 Similar: 








-John


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