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Experience:  Contractor-42+ Years in the ElectricalTrade
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# Commercial electrician needed: I have an issue with greenhouse

Commercial electrician needed: I have an issue with greenhouse lighting ballasts:and GE lamps:
The ballasts involved are an electronic and a traditional magnetic. The electronic ballast says it uses 765 watts to run a 750 watt HPS lamp. The magnetic ballast says it needs 810 watts to run the same lamp...and it seems to be burning brighter.....Is this likely to reduce the life expectantcy of the lamp if it is drawing more than it is rated for???
If there is some documentation or a link that shows a similar study and results that would be my first choice to refer to.....as well as any first hand experience
Hi, I'm Mike and I'll be glad to assist you. The output of the ballast is for the lamp listed and the wattage of the ballast is mute. An electronic ballast will have a longer service time.
Customer: replied 3 years ago.

Hi:

What I am looking for is an answer to the higher wattage consumption of the lamp and whether that higher power consumption will shorten the life expected of the lamp...and ideally I am looking for the results of a study or testing on the subject or something very similar

let me opt out and possibly one of the experts who are engineers could better answer your question.

Welcome. My name is XXXXX XXXXX would be glad to assist.

What are the Make and Model numbers of the ballasts?

Output of a 750 watt ballast is just that, 750 watts.
Input is adding the losses of the transformation inside the ballast so it represents the output 750 plus losses.
One ballast costs 50 watts of lost power just to operate and the other is 15 watts
So, inputs are different but output is still 750 watts.

Magnetic ballasts have higher losses because of the transformers inside and heat loss along with poorer power factors which uses more input than the electronic type.

Lets see your models and maybe there is information that will assist in why the lamp is brighter on the magnetc ballast.

Customer: replied 3 years ago.

Sorry to be annoying but really my question is about the life of GE 750 Watt HPS lamps being used in an electronic ballast and a magnetic ballast. I am looking for testing results or an informed expert opinion about whether the magnetic ballast sending 810 watts through the 750 Watt lamp will have a shortened life effect on the lamp, in comparison to the electronic ballast sending 765 watts through another, but same brand of GE lamp.

Ok, thanks.

It is not annoying, we are here to provide information as best we have and have access to for you.

As for the your posting, I think you are confusing the input and output.

The magnetic ballast does not send 810 watts to the lamp, it only outputs 750 watts.

The 810 watts is what is consumed total by the ballast.

It costs wattage just for the ballast to operate, so in the case of the magnetic ballast, it cost 60 watts of power to run the ballast. That is what it takes inside to power the components along with any heat losses and power factor losses. The lamp NEVER sees that wattage.

It ONLY applies 750 to the lamp. It consumes 60 watts itself.

Maybe that will give a better explanation than before.

As to the life expectancy, I would need your information as the life will vary with manufacturers as that is determined how well they are made as far as quality goes.
All manufacturers are different and all will have different life expectancies and that information should be published.

If you give me the Lamp manufacturer you are using, and the Model number, I am sure I can find that information?

Customer: replied 3 years ago.

Hello:

Just to confirm: The magnetic ballast or the electronic ballast will send the same amount of power, 750 watts, to the lamp. The ballast itself either at 765 for the electronic or 810 for the magnetic, is what is consuming the wattage.....

The Lamp is a GE Lucalox 400v/750w PSL : Actual Part Number LU400V/750W PSL

Finally: will the magnetic ballast or the electronic ballast operation have a different effect on the life expected from the lamp? Longer or shorter or the same....???

With your answer I will rate your response as 5 Stars and probably not have a follow-up...Thank you.

Just to confirm: The magnetic ballast or the electronic ballast will send the same amount of power, 750 watts, to the lamp. The ballast itself either at 765 for the electronic or 810 for the magnetic, is what is consuming the wattage.....

-Yes, you are correct. The ballast consumes those wattages not the lamp
Lamp only gets the 750 to operate

CLICK HERE and get the specifications of that lamp. First 4 pages are all on that lamp.

It is recommended to replace every 10,000 hours which is a short life compared to others I see with life of 20,000 hours and more.
Of course, proving in the field is always better than the paper that specifies information.

Here is one of them
Manufacturer: General Electric
Model: LU 750 HPS SYL
Wattage: 750W
Lu mens: 105,000
Color Temp: 2100K
CRI: 22
Finish: Clear
Base: Mogul E39
ANSI Code: S106
Burn Position: Universal
Bulb Life: 24,000 hrs

Finally: will the magnetic ballast or the electronic ballast operation have a different effect on the life expected from the lamp? Longer or shorter or the same....???

Technology has improved on the electronic ballast and I believe today they offer better reliability and keep lamps at efficiency better than magnetic ballast.
Use to be they had issues in the beginning and had a higher lamp failure rate but times have changed in my opinion and experience.

They use less energy, have less noise, produce less heat and last longer than the magnetic ballast.
They do cost more in most cases, so changing should be on a dead replacement pattern to minimize changeover costs.

I believe the magnetic ballast will begin to fade out of the market sometime in the future with all of the energy savings the government is working towards.
Unknown when of course.

AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4241
Experience: Contractor-42+ Years in the ElectricalTrade
Customer: replied 3 years ago.

Do you have or can you supply a link that shows a side by side study or test of a magnetic to an electronic ballast for power consumption....?

Customer: replied 3 years ago.

Actually I do need further help in actually testing a magnetic ballast and an electronic ballast for watts consumption....I have an older watt meter with a moving needle and probes.

I have had a number of ballasts on our test bench as tested for their operation and simply connected a plug into in input side of the electronic board, then plugged output side connector for the lamp, and finally turned on the power for the unit to test that a light installed in the bulb holder would light.

This is 347 volts and I am careful and any other work that needs to be done is handled by a neighbor who is in his last year of apprenticeship.

The input is 3 wires, black, white, green and my guess is to measure across 2 of those wires....but my question really is where do i measure to get a reading of watts for the operation of the ballast.

Input wires black and white are the leads for the measurement.
Black being hot and the white is neutral.

Put an amprobe and measure the amperage, multiply that by the voltage you read and that will give an estimated wattage.

Will not account for any power factor but fairly accurate.

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