LED parking lot replacement corn cobb style bulbs ( FYI )

Davebones

Senior Member
This weekend we just replaced 50 of our 400 watt metal halide pole lights with the Olympia CL-100W11H-55K-E39 corn cobb style LED lamps .We had replaced 8 of these about four months ago and are very happy with the light output . Plan on doing the other half of our parking lot next . We originally had thought about replacing the whole fixture with LED type fixtures but decided to got with LED corn cobb style bulbs due to the cost . The lamp is rated 50,000 hrs and has a 5 year warranty . Has anyone done any similar and how long did they last ?
 

Davebones

Senior Member
We removed the old 400 watt metal halide ballast and wired 480 volt straight to the socket . The driver and everything is built inside the corn cobb LED style bulb from what I understand .
 

steve66

Senior Member
The biggest advantage of LED (at least from an energy efficiency standpoint) is that the light can be directed by aiming the LED's.

With LED there is no need to use mirrors and reflectors to reflect the light that goes up back down (with much of it going back into or through the lamp) toward the ground.

So my personal opinion is that it is usually a waste to replace MH lamps or Fluorescent lamps with LED replacements that just try to mimic the distribution of these lamps and fixtures. You probably wind up with something less efficient than what you started with.

So IMO, the only way to reliably improve efficiency of a MH or LED lamp/fixture is to replace the entire fixture with an LED fixture. Something that is designed from the ground up for the directional properties of LED's.

On the other hand, Incandescent lamps are so inefficient to start with that LED replacements are almost always better.
 

PaulMmn

Senior Member
Location
Union, KY, USA
I was at a demo one time, and the presenter lit a fluorescent tube, then an LED stick with the same light output, and nearly blinded us! Because all of the light went in one direction.

A lot of the fluorescent tube LED replacements are a 'strip light,' with the LEDs on one side. Some will pivot a few degrees so you can optimize coverage.
 

tom baker

First Chief Moderator
Staff member
So my personal opinion is that it is usually a waste to replace MH lamps or Fluorescent lamps with LED replacements that just try to mimic the distribution of these lamps and fixtures. You probably wind up with something less efficient than what you started with.

So IMO, the only way to reliably improve efficiency of a MH or LED lamp/fixture is to replace the entire fixture with an LED fixture. Something that is designed from the ground up for the directional properties of LED's.
i agree 100%. I was a member of the IES and attended the Street and Area Lighting conferences for many years and saw the beginnings of LED in 2008. An HPS or MH lamp is a point source and putting in a corn cob LED lamp yields poor photmetrics. Most failures in LED sources are the driver, and in a cord cob they are in the lamp. One big issue with LEDs is heat and a new fixture will be designed for that

Replace the entire fixture, there are many quality mfgs now, GE, Hubble, etc. Your local wholesale house will have lighting department who can assist with meeting the IES requirements. Also look for POCO rebates.
I would also suggest a 7 pin PE socket instead of a 3 pin, the 7 pin allows monitoring and control, but a 3 pin PE can be used
Replace the entire fixture and it should be good for 20 years.
 

steve66

Senior Member
I was at a demo one time, and the presenter lit a fluorescent tube, then an LED stick with the same light output, and nearly blinded us! Because all of the light went in one direction.

A lot of the fluorescent tube LED replacements are a 'strip light,' with the LEDs on one side. Some will pivot a few degrees so you can optimize coverage.
That may be a little better, but these will still be installed inside a fixture with all the optics designed for a fluorescent tube.

Its just so much better to fixtures designed for LED's.

Unscrupulous sales people will often overstate the benefits of their products by ignoring the effects the fixture has on the light.

When you buy a quality LED fixture, the light output, losses, and efficiency listed is always for the entire system - lamp and system. When an LED fixture says it provides 4800 lumens, that's pretty much the whole story.

A LED corn cob lamp may also provide 4800 lumens, but once its placed in a fluorescent fixture, you may only get 3800 lumens. Salespeople tend to ignore that last number.
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
Be careful who you purchase new LED fixtures from. 20 Years might be a bit of a stretch.

https://www.freep.com/story/news/lo...19/05/07/detroit-streetlights-led/1134222001/

MTW Ω
Yes, and what you bought last month is not the same as now, nor next month.

Local supply house replaced an LED fixture that suffered premature EOL. The minor problem being that, although it is supposedly the same fixture, the color difference is noticeable enough the customer wants them all replaced. Free, off course.
 

Davebones

Senior Member
Corn cobb replacement update

Corn cobb replacement update

Just finished this weekend replacing the remainder of our 400 watt parking lot pole lights with the corn cobb LED style bulbs . We originally started this in January 2019 and as of now have not had any failures . The first ones we installed look as bright as the day they were installed . We removed the old 400 watt MH ballast and wired these straight to 480 volt . Very happy with the results we've got with these ...
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
i agree 100%. I was a member of the IES and attended the Street and Area Lighting conferences for many years and saw the beginnings of LED in 2008. An HPS or MH lamp is a point source and putting in a corn cob LED lamp yields poor photmetrics. Most failures in LED sources are the driver, and in a cord cob they are in the lamp. One big issue with LEDs is heat and a new fixture will be designed for that

Replace the entire fixture, there are many quality mfgs now, GE, Hubble, etc. Your local wholesale house will have lighting department who can assist with meeting the IES requirements. Also look for POCO rebates.
I would also suggest a 7 pin PE socket instead of a 3 pin, the 7 pin allows monitoring and control, but a 3 pin PE can be used
Replace the entire fixture and it should be good for 20 years.
I don't understand the poor photometry with a cob lamp. If you leave the reflector in the HID fixture I would think that is would be similar, ( other the light cannot pass from the reflector through the lamp like in a HID)
 

Davebones

Senior Member
We didn't measure the light output but it looks brighter with the LED's . For what a new fixture would cost it was well worth it to retrofit the lights with the LED's if we get the life expectancy out of them . Replaced some 250 watt fixtures at our gate and on the side of the building and are happy with how those turned out too ...
 

tw1156

Senior Member
Location
Texas
I don't understand the poor photometry with a cob lamp. If you leave the reflector in the HID fixture I would think that is would be similar, ( other the light cannot pass from the reflector through the lamp like in a HID)
Poor photometry would be a relative term here as it's all on what you're evaluating; HID is notorious for bright spots beneath the pole and less light further from it with traditional optics which can yield to poor site uniformity (max/min ratios) so sites with better uniformity may actually have lower light levels because your eye perceives it as being brighter than when a site has a really bright spot, and then dark spots between poles. Corn Cobs can be an appropriate solution for cost depending on the application (ie, parking garage retrofit with high ceilings) versus a roadway light with a corncob style that utilizes the traditional reflector.

LED's can still be glary across multiple manufacturers and there is more to evaluate than just lumens and optics; the amount of lumens measured across certain angles cause nuisance glare (60 - 80 degrees). The benefits and why sales people tout certain fixtures is they may have a higher amount of lumens coming at a higher angle and then saying they can space their pole XX feet further than traditional source. Many times we ignore this glare component, but I'd argue that this factor should be just as important, especially for municipalities evaluating their lighting standards.

We should think what the purpose of the light is for in each application and then design around those parameters in determining visual comfort as well and if it's even a factor.
 

MAC702

Senior Member
Location
Clark County, NV
I don't understand the poor photometry with a cob lamp. If you leave the reflector in the HID fixture I would think that is would be similar, ( other the light cannot pass from the reflector through the lamp like in a HID)
The reflector is designed (focused) for the, relatively speaking, point-source of the light at the center of the bulb. Some applications will be more noticeable than others.
 
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