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The hidden, extremely costly LED lighting maintenance

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    Originally posted by ActionDave View Post
    His inability to be succinct is a big reason he looses credibility with me.
    To me its not so much the succinct aspect, I enjoy an in depth descriptive discussion, but rather that the conversation seems one sided. Any positives regarding LEDs are ignored, and there is a constant fixation on the occasional pitfalls of a technology still maturing. Further when posting facts which contradict or prove statements wrong (like instant re-strike igniters for 5kv pulse rated sockets) he just ignores them.

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      Originally posted by tw1156 View Post
      I incorrectly stated earlier by saying the MLO was the guide for the LED luminaire specification; the document that was used was actually put out by the DOE and was labeled MSSLC (Model Specification for LED Roadway Luminaires). https://energy.gov/eere/ssl/download...luminaires-v20 The DOE provided a lot of base information for Municipalities to incorporate into their specifications when evaluating LED luminaires.

      The MLO was referenced as a guide for best practices in choosing luminaires, but is more of an "aesthetic" guideline (full cutoff, reduced glare, etc)
      I think spaz blinking is one of those things that did not cross their mind just like power factor and THD when standards were initially made for CFLs. Many CFLs actually have a bridge that plugs straight into the utility with a big capacitor across it which makes for great DC link regulation but power factor that is close 0.6 or so with 100%+ THD as well as very high inrush.

      They put a restriction on power factor and essentially all EnergyStar lamps and fixtures have to have 0.9 of higher PF. Along with this is a meaningless guideline that allows flicker as long as it's 120Hz or greater but did not set a limit on how far it can notch down or a flicker index value. So there are LED products that simply use strings of multi-tapped LED strings that are paired with fast semiconductor tap changers that extends and shortens the length each half cycle to reduce cut-in voltage to lower harmonics. But these design have enough non-electrolytic capacitor to keep the controller energized and light drops to zero twice every cycle with the output pulsation closely following the stepped sinewave. The flicker is worse than fluorescent as there's no afterglow in LED phosphors to dampen the flicker. Since the restrictions weren't made on flicker index, this was a loophole used to meet the requirements of power factor and stay within the flicker limits of the rules but excessively flickery in application. In general, commercial application external fluorescent ballasts are very well regulated that convert AC into DC link with very little line frequency ripple and many often provide output with less flicker than high wattage incandescent that any sign of 120 Hz pulsation is hardly visible on light sensor fed into oscilloscope with some of well designed ballasts with flicker comparable to that of studio production flicker suppressed lights.

      Despite the fact LEDs already having inferior flicker dampening on its own, many LED fixtures have LED ballasts with far inferior flicker regulation than common pin-based CFL linear lamps. Ballast is one of the places LED products often cut corners in order to be able to meet the price point while using LED elements that can meet specs. Although dedicated voltage ballasts have become nearly obsolete, they've made a come back with LEDs. While there are dedicated voltage ballasts wtih constant-wattage regulation, most single voltage ones are not. So keep this and the fact many brand name ballasts are built to commercial use durability when you wonder why T5/T8 fluorescent ballasts cost so much relative to cheap LED fixtures. Many LED ballasts are also incapable of isolating load power delivery with a +/- 10% line voltage variation which means. So like 1990s T8 ballasts, you can not ignore line voltage fluctuation unless you specify line regulation. High line voltage causes over illumination, acceleration of LED element degradation and wasted energy while low line voltage causes output reduction.

      Originally posted by mbrooke View Post
      To me its not so much the succinct aspect, I enjoy an in depth descriptive discussion, but rather that the conversation seems one sided. Any positives regarding LEDs are ignored, and there is a constant fixation on the occasional pitfalls of a technology still maturing. Further when posting facts which contradict or prove statements wrong (like instant re-strike igniters for 5kv pulse rated sockets) he just ignores them.
      I acknowledge LEDs have their place such as generic residential lighting application that has strong expectations of immediate start but tend not to accumulate that many hours per year on average.

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