Electric-Light
Senior Member
Lithonia KAX2 LED is 32,000 lumens on the very first time you power it up. That's pushing it even with a 1kW probe start MH. You're really pushing it with a HPS which has a much better lumen maintenance than MH as well as higher initial efficacy. Note their sales pitch "replaces up to 1,000W MH". Which should be interpreted the same as a 16oz water bottle that holds "up to" 16 oz.
A 1kW HPS starts out at 130,000 lumens. Yes one hundred and thirty thousand. For a parking lot light, any light not leaving the fixture all and light emitted above the horizon line is wasted. The amount of light not shot into the sky or trapped in the fixture depends wildly on the existing fixture.
Something to keep in mind:
Lumen is a unit weighed to our eye sensitivity. Our eyes are substantially more sensitive to higher kelvin light at very low lighting level which is why a few 13W 6500K CFLs will allow you to see good enough to walk around a big warehouse and does so better than when using the 2700K version with the same output. Try it yourself. This gimmick has been used by many ESCOs to pitch higher kelvin lamps as more efficient so they can pocket the credit. As the illumination level increases, the magnification drops. The naturally low reflectivity of pavement means lower level seen by the eyes and this can make higher kelvin lighting appear brighter.
As for evaluating the useful life, try not to rely too much on testimonials. It depends on where you draw the cut off and life follows the bottom curve. A HPS only lasts 10,000 hrs if your cut off is 5% burn out, but can go 25,000 hrs if the cut off is closer to 30% burn out. If you have 100 lamps in use, you'll probably lose one or two at 6,000 hrs and a few surviving over 40,000 hrs. So a claim like "I know a guy who has *a* lamp and it went bad in a year" this isn't a useful information.
Unfortunately, LED ballast is far more likely to fail suddenly than a coil and core ballast, so never assume that LED systems don't burn out.
Subjective qualities are important, but ESCOs have always had all kinds of tricks up their sleeves to use subjective qualities to cover up objective deficiencies. If you cut off any corners, it will be noticed. so they've always been playing the game of how much materials can they remove by sanding without getting noticed while conveniently avoiding the topic of weighing it. Instead of just accepting what feels good, I prefer meeting specifications and absence of feeling wrong.
The really tricky part lines in the interpretation on "wasted" light. The same exact pole could be more efficient since there's less light lighting up beyond the parking lot. Never take before and after pictures most ESCOs use for sales pitch too seriously. I think we all have pictures we took of someone that turned up with the face very dark or background washed out beyond recognition. No matter how you play with the exposure settings, cameras have trouble matching our eye's dynamic range that lets us see someone's face and the background at the same time.
A sharp cut off can increase the apparent efficiency but it also makes it easier for crooks casing the perimeter to stay less visible in the darkness or in landscaping. Needless to say, this reduces the effectiveness of security lighting and makes it more posh for criminals which will cause more to come. Pay attention to lights in tunnels and you'll see that the illumination level is gradually tapered down towards the end and this is to ease the drivers' transition into the darkness.
You shouldn't alter lighting systems without a lighting design consult.
CRI, or Ra8 uses a sample of eight pastel colors to determine how accurately those specific color chips are rendered to human eyes.
Most LED products are completely lacking violet light beyond deep blue and have a gaping spectral flaw between blue and green and suffer from inability to render turquoise/blue green color properly and tend to shift them bluer. Clear coat and many detailing products are UV interactive but they will fail to activate under LED lighting. Non-UV producing is an advantage in many cases but its also a convenient bail out for LEDs as they're not able to economically emit in the UVA-violet region.
Pigments that have reflectivity between blue and green are particularly vulnerable to false rendition by LEDs.
A mix of halogen and wide spectrum fluorescent lamps like CHROMA 50 or high color rendition CMH have a lead over LEDs. CMH have continuous emission ranging from UVA to deep red.
Many computers from 1990s are still operational including its electronic power supply. Although someone with engineering background should know that "i have one or two samples in personal use" is not statistically significant. Electronic ballasts do not get a fan like computer power supplies so they're used in harsher environments. Temperature affects failure probability. For ballasts that are rated for 90C case temperature, some have 5 year warranty at 75C and only 3 years at 90C.
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