Why does fluorescent require ground

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benaround said:
ironphill, Except at the Main Service Disconnect, you never, ever, ground the

neutral to anything !!! I don't know what you mean by " like you would at a

GFCI ", but if you are jumping the neutral to an enclosure, stop doing it. OK ?

I see you are just starting out in the trade, if you think you are going to

stay with it, then, go to this site as often as you can it will really help.
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I am very well aware that this is a bad idea. I did a T and M job and at apartment complex where in one unit I had no nuetral at some outlets. Found these 4 outlets were the only thing on this breaker. I searched every other box in the apartment and found no bad connection. Checked at panel had it there. Already had a bill of 3 hours by now and management was not interested in me cutting any sheetrock. So took a piece of 14 solid and and wrapped it around the nuetral screw and ground screw. and everything came on like it should. This was the only time I had done this and would never do it again. Any long term dangers involved?
 
benaround said:
ironphill, Except at the Main Service Disconnect, you never, ever, ground the

neutral to anything !!! I don't know what you mean by " like you would at a

GFCI ", but if you are jumping the neutral to an enclosure, stop doing it. OK ?

I see you are just starting out in the trade, if you think you are going to

stay with it, then, go to this site as often as you can it will really help.
Click to expand...


I was in a spot once and running out of time. Had no neutral so I jumped the neutral and ground together in one outlet and got the rest of the outlets to work. I have no plans of going against my better judgement again. Are there any dangers involved with this practice?
 
Using the ground for an neutral is a bad idea I get that and always us my best judgement and still call the boss when working. Are there any dangers invovled with this practice?
 
080830-1225 EST

Yes there are dangers.

Suppose that ECG wire gets broken near the breaker box, or a loose joint in the EGC. Now put a low impedance load on this circuit. You may raise the potential of the ECG to the hot line voltage. This in turn makes the chassis (outside surface) of all equipment connected to this circuit with 3 prong plugs at the potential of the floating ECG relative to earth.

You have not provided a legal or satisfactory solution.

You need a very good understanding of the purpose of the ECG and how it can reduce the likelhood of a shock or worse.

.
 
080830-1305 EST

As I mentioned above. I do not believe there is any need to ground the sheetmetal of a fluorescent fixture in order to get the lamp to light. In other words it could completely float. Is this satisfactory for other reasons? NO.

.
 
gar said:
080830-1305 EST

As I mentioned above. I do not believe there is any need to ground the sheetmetal of a fluorescent fixture in order to get the lamp to light. In other words it could completely float. Is this satisfactory for other reasons? NO.

.
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Many ballasts will have notes on them that say the lamps must have a grounded metal reflector installed within 1" of the lamps.

From Advance Transformer

TROUBLESHOOTING RAPID START INSTALLATIONS
The Rapid Start circuit (described on page 7) eliminates the
annoying flicker associated with starting Preheat systems.
Rapid Start circuits also simplify maintenance since no
starter is used.
The Rapid Start lamp operates on the principle of utilizing a
starting voltage which is insufficient to start the lamps while
the cathodes are cold but is sufficient to start the lamps when
the cathodes are heated to maintain emission temperature.
This voltage range between starting cold and starting hot is a
very narrow band of voltage which must be closely controlled
in order to prevent either failure of the lamps to start or instant
starting of the lamps with cold cathodes which is detrimental
to the lamps.
In order to stay within this range of voltage, it is necessary
to excite the gas within the lamps by means of an external
voltage which is applied to the gas within the lamps to create
ionization. This external excitation is created by means of the
capacity that is present between the lamp and the reflector
or channel. In order to act effectively, the fixture must be connected
to ground and the white lead of the ballast connected
to ground lead of power supply. Thus it is stated on the label
of Rapid Start ballasts ?MOUNT LAMPS WITHIN 1/2 INCH
(3/4 INCH or 1 INCH) OF GROUNDED METAL REFLECTOR.?
The majority of new fluorescent installations today use ballasts
of the Rapid Start design. The HIGH OUTPUT (800 MA), and
VERY HIGH OUTPUT (1500 MA) lamps are of the Rapid
Start design.
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From page 9 of this pdf http://www.advancetransformer.com/uploads/resources/flb-troubleshooting-guide.pdf
 
080830-1349 EST

iwire:

This may be true of Rapid Start and reduce mercury content. Rapid Start uses a heated filament to help initiate ionization, but not heated to the temperature that results after full lamp current flows. Thermionic electron emission increases with filament temperature. If this initial filament temperature is kept low, then it will take longer for the lamp to start. To improve efficiency or reduce ballast costs it appears that from your reference that tricks are being played to make use of the electric field near the tube to improving starting.

In the case of an Instant Start Slimline a high enough initial voltage is provided that an initially heated electrode is not required to initiate ionization. Looking at a new Universal ballast it says that the ballast must be grounded, but it does not state this is required for the light to work. And it is not required to work. It is a safety requirement.

I do not have a convenient 4' assembly to see what happens if the sheet metal is floated, or there is no sheet metal. My guess is that it will likely start.

.
 
gar said:
080830-1349 EST

I do not have a convenient 4' assembly to see what happens if the sheet metal is floated, or there is no sheet metal. My guess is that it will likely start.
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How do CFL's start? Or is this apples and oranges?
 
gar said:
080830-1349 EST

iwire:

This may be true of Rapid Start and reduce mercury content. Rapid Start uses a heated filament to help initiate ionization, but not heated to the temperature that results after full lamp current flows. Thermionic electron emission increases with filament temperature. If this initial filament temperature is kept low, then it will take longer for the lamp to start. To improve efficiency or reduce ballast costs it appears that from your reference that tricks are being played to make use of the electric field near the tube to improving starting.

In the case of an Instant Start Slimline a high enough initial voltage is provided that an initially heated electrode is not required to initiate ionization. Looking at a new Universal ballast it says that the ballast must be grounded, but it does not state this is required for the light to work. And it is not required to work. It is a safety requirement.

I do not have a convenient 4' assembly to see what happens if the sheet metal is floated, or there is no sheet metal. My guess is that it will likely start.

.
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I love it when people believe they know more about a product then the people that make it. :grin: :roll:

It is clear the manufacturers designs rapid start lamps to operate with a grounded metal reflector within a close distance to the lamp.

Might it light without the grounded reflector? Certainly.

But for best results it should be installed per code and per design.
 
iwire said:
I love it when people believe they know more about a product then the people that make it. :grin: :roll:
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I'm almost 100% sure that gar has a good grasp on these concepts, despite not being involved with the manufacturing of ballasts. :cool:
 
gar said:
Looking at a new Universal ballast it says that the ballast must be grounded, but it does not state this is required for the light to work. And it is not required to work. It is a safety requirement.
Click to expand...

So when the manufacturer of the product says

Thus it is stated on the label
of Rapid Start ballasts ?MOUNT LAMPS WITHIN 1/2 INCH
(3/4 INCH or 1 INCH) OF GROUNDED METAL REFLECTOR.?
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It is just a safety requirement?

Or the fact that the manufacturers troubleshooting check list for for failure to start includes checking grounding of the ballast and fixture that has nothing to do with operation but is also just a safety check?

I have a battery operated compact florescent that needs no ground to operate, that does not mean that all fluorescents should not be grounded for proper performance in addition to safety reasons.
 
peter d said:
I'm almost 100% sure that gar has a good grasp on these concepts, despite not being involved with the manufacturing of ballasts. :cool:
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Gar is extremely knowledgeable and intelligent, but if the ballast manufacturers say a grounded metal reflector if required for proper operation of rapid start lamps then that is what I will believe.

It seems to me the people that spend 5 days a week working with the product are likely to have learned more about the products then most ... including Gar.
 
iwire said:
Gar is extremely knowledgeable and intelligent, but if the ballast manufacturers say a grounded metal reflector if required for proper operation of rapid start lamps then that is what I will believe.

It seems to me the people that spend 5 days a week working with the product are likely to have learned more about the products then most ... including Gar.
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True, but I don't understand the electrical reason why grounding is required in proximity to the lamps. I have often wondered about this in the past. I certainly would like to find out. :)
 
peter d said:
True, but I don't understand the electrical reason why grounding is required in proximity to the lamps. I certainly would like to find out. :)
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Then you did not read the info already provided.

In order to stay within this range of voltage, it is necessary to excite the gas within the lamps by means of an external voltage which is applied to the gas within the lamps to create ionization. This external excitation is created by means of the capacity that is present between the lamp and the reflector or channel. In order to act effectively, the fixture must be connected to ground and the white lead of the ballast connected to ground lead of power supply.
Click to expand...
 
iwire said:
In order to stay within this range of voltage, it is necessary to excite the gas within the lamps by means of an external voltage which is applied to the gas within the lamps to create ionization. This external excitation is created by means of the capacity that is present between the lamp and the reflector or channel. In order to act effectively, the fixture must be connected to ground and the white lead of the ballast connected to ground lead of power supply.
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Bob, doesn't this meea that the ballast intentionally places a current on the EGC at least during starting?
 
iwire said:
Then you did not read the info already provided.
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No, I didn't. I don't normally read your posts. :D

But I still don't completely understand the process. I'm guessing they are using capacitance to start the lamps.
 
iwire said:
That is my limited understanding and I bet someone here could explain it.
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I think Gar alluded to it earlier when he said:

To improve efficiency or reduce ballast costs it appears that from your reference that tricks are being played to make use of the electric field near the tube to improving starting.
Click to expand...

The only thing that comes to my mind is capacitance.
 
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