Mercury vapor to LED conversion- need opinions please

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Old 04-15-15, 08:11 PM
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Mercury vapor to LED conversion- need opinions please

Hey all,
I'm considering changing nine obsolete outdoor 175W mercury vapor area lights to LED fixtures. It seems that most of the LED area fixtures on the market have an output between 2,600 to 3,400 lumens, which seem low compared to the 8,000 rated lumens of the old 175 watt units. Yet, they are being marketed as an equivelent replacement. The two units I'm considering are the 26 watt RAB YBLED26, and the 40 watt Hubbell DDL-9. Both seem to be quality fixtures. I have a fair amount of experience in lighting, but not too much with LED's yet.

Anyone have any experience with a changeout like this? How did the overall illumination compare? All thoughts welcome!
Thanks,
Andy
 
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Old 04-16-15, 04:57 AM
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Good move! I would go with the RAB ,I would also contact their tech support on their web site and tell them what your plan is and get their opinion, they have been very helpful to me, also check with your local POCO and see if they are offering any replacement rebates,it's worth a shot.
Geo
 
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Old 04-16-15, 06:11 AM
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I would estimate that a typical streetlight with incandescent or mercury or sodium lamp and domed reflector just above the lamp will lose about a third of the total lumens to various optical inefficiencies including light absorbed by the mechanical and/or structural parts around the perimeter between the reflector and the glass cover.

Meanwhile typical LED streetlight or streetlight conversion lamp emit all of the advertised output of light down onto the roadway.

For LED streetlights you really need to do some analysis of how rapidly the illumination falls off as you move away from directly under the fixture. Some have a more severe fall off compared with mercury or incandescent fixtures. You would have to select lamps with a desired distribution or use a special glass cover underneath (may come with the fixture) that spreads out the light as desired.
 

Last edited by AllanJ; 04-16-15 at 06:33 AM.
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Old 04-16-15, 10:13 AM
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Thank you both. Geo, glad you mentioned the poco rebate. I'm pretty sure they are doing this in my area, so I'll check with them. Allan, I was thinking the same thing as far as light distribution, and am a bit concerned about a bright spot directly under the fixture, as these fixtures are only 15' or so above the ground. I think I'm going to go with the RAB, and get one first to see how it works out.
Thanks again,
Andy
 
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Old 04-16-15, 10:36 AM
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Don't to check with RAB for any recommendations they may have.
Geo
 
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Old 04-24-15, 02:04 PM
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Update

I went with the RAB YBLED26N. I am floored at the light output and the quality of the fixture. Easy to install and casts an even bright light. I will be converting the other eight fixtures soon.

Here's a "before" shot of one of the most beaten-up old fixtures:
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Here's an "after" shot:
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My facility will drop from 1,725 watts to only 234 watts total for outdoor lighting. The energy savings alone will pay for the fixtures in only two years!
Andy
 
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Old 04-24-15, 04:31 PM
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Nice!did you get any rebate money from the POCO?one of the parking lots at a building I used to work at converted from 400 HPS to LED's and there are motion detectors that sense up to 300' so often times the lot is totally dark,POCO picked up a big chunk of change for that conversion.
Geo
 
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Old 04-24-15, 05:31 PM
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The other benefit is that the LEDs will come on right after a power outage vs the sodium that will have a delayed strike,
 
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Old 04-24-15, 06:14 PM
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Yes, we will get a nice rebate from Focus on Energy. Since we are planning on replacing eight more soon, we will submit all the paperwork at once. We will get $40 back for each 175W mercury fixtures we retire, and $50 for the two 250W mercury units. Those two over-light their areas anyway, so I will use the same 26W LED units that are replacing the 175's.
As Allen mentioned, the LED's do a great job projecting their light directly where it is needed, with much less wasted light. Although the output lumen level is lower, the lit areas still seem about as bright.
One unusual advantage of the new fixtures for us, is that they are smaller & do not have the top-mounted twist-lock photocells. This facility is a TV station with an 1800' tower behind the building. During the winter, the entire property is bombarded by ice chunks falling off the tower. Most of the old fixtures have been hammered with ice, destroying the photocells & the optical assemblies.
We'll see how these handle it...


Andy
 
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Old 04-24-15, 06:27 PM
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It seems that most of the LED area fixtures on the market have an output between 2,600 to 3,400 lumens, which seem low compared to the 8,000 rated lumens of the old 175 watt units.
It seems in an indirect way you have learned that the advertised lumens of the old mercury lights is initial lumens and not the mean lumens. Mercury lamps will decline in their lumen output from the first day they are installed. Sure, mercury lamps can last almost forever, but toward their end of life a candle will provide more useable lumens.
 
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