low pressure sodium lights

[rp2813]

Traffic Signals

The quick failure of traffic signals gives me reason to be concerned about the life expectancy of LED street lamps.

 

Several years ago when post-deregulation delivery of electrical power fell short of needs and we experienced black-outs, brown-outs and costs for electricity soared all over the state, cities quickly went to total LED traffic signals.  Many signals had already been changed to LED for the red only,  but suddenly the green ones were changed out in nearly every city in the bay region, and some of them were failing within weeks. 

 

What I find interesting is that the red LEDs don't seem to have anywhere near the failure rate of the green ones.  I don't know what the implications are for clear lights, if any.

 

On the vast majority of signals in Bay Area communities the amber remains incandescent, likely because changing to LED wouldn't be so immediately cost effective as with red and green.

 

[tolivac]

Most of the traffic lights in Greenville are now LED-all colors-yes,you do see some failed LED's in any of them.Since snow isn't a problem here-the lights work fine.

 

[kb0nes]

I haven't seen a NEW traffic light installed anywhere in MN in the past 10 years that isn't fully LED. Initially there was a trend to retrofit only the red portion of the existing lights. I'm not sure if it was because red LED's tend to be the cheapest to make or because liability is more of an issue if the red lamp doesn't work, I suspect the latter.

Of course with any new technology, as LED retrofits for traffic signals was years ago, there is the possibility of failures. I have seen a few lights that have an LED or two dark on the array. A few years ago I saw some of the red LED arrays for traffic lights at AxMan surplus. The array was built out of leaded low power indicator LED's. My hunch is that today they are made with surface mount power style LED's which would be much more reliable.

Bear in mind that the white LED's we are using for lighting are actually ultraviolet emitters that are exciting a phosphor to create the broad band white light. Yes they have difficulty with "Lumen maintenance" (loss of light output over time), but unless their safe operating temperature is exceeded, they will maintain brightness as well or better then any other form of light I can think of.

As for snow or icing being a hazard to LED lamps, they would actually work better frozen in a block of ice! No thermal issues that way and the junction voltage is so low that water would cause no harm. Other then high temps the only other things that could shorten an LED's lifespan are surges and these can be easily controlled with a TVS avalanche diode or MOV. Compared to an incandescent lamp any properly designed LED will outlast it by any order of magnitude at the least.

 

[tolivac]

Phosphors in white LED lights-think the phosphors break down in time-this happens with flourescent bulbs and mercury and metal halide bulbs that have phosphors in them.The brightness and "color" of the light changes and dims.Otherwise the light still works.Stores lit with MH bulbs in open fixtures love the phosphored MH bulbs-they don't have glare and give a softer,more even light.Thats a good point for LEDS-they don't mind cold conditions that other light sources don't like-the extreme cold may not permit the light to start-flourescents,Mercury and probe start metal halide.Pulse start metal halides are more tolerent of cold-they can start more easily.But--Hids don't like extreme heat.Same with flourescent-MH bulbs are more tolerent of heat.Only danger is will the ballast get too hot-and fail.In a well designed fixture-the ballast is below the optical-so the heat from the bulb won't cook the ballast and its capacitor or ignitor.With light technology going the way it is-incandescent light fans are going to have to STOCK UP and buy as many CASES of bulbs they can.
I have also seen the LED traffic lights at surplus sales,too-these typically have MANY of the LEDS burned out.Yes,think fixture makers are going to the "chip" type LEDS as opposed to the individual "pilot light" ones.I have a flashlight that is multicolor 4 LED types in it-UV,Blue,Red,Green.The Powertac Chameleon.With some of its switch combinations you can mix the colors.You can see the phosphors of white LEDs by shining a UV lamp into them.

 

[supersuds]

I dunno about stocking up on incandescents...

I overreacted a couple of years ago and ended up with about 12-14 4-packs of 100 watt bulbs. (There are different varieties, such as GE Reveal and Sylvania Daylight, as well as regular yellow bulbs.) Yet, I currently only am using 100 watt bulbs in a grand total of ONE lamp. Assuming they last a year, I'm well fixed unless I live to be over 100. Sheesh.

On the bright side, they weren't expensive, so no great loss even if they end up being tossed.

I bought one of the Cree LEDs for a stairwell light that is on a lot. It's a big improvement over CFLs, which are slow to light up, and the energy consumption makes it a better choice for this location than an incandescent. Still, the light is on the bluish side and I wouldn't like that everywhere in the house.

 

[retro-man]

I just read that as of January 2014 they are no longer going to make 60watt and 40 watt regular bulbs. all are going to be one of the 3 new forms of lighting. They still will make higher wattages for special lighting. So now do we want to stock up on a few of these before there gone?

 

[kb0nes]

John (Supersuds), I'm glad you bought one of the Cree LED replacement lamps, they are the most incandescent like and most cost effective lamp available today. Nice that they are made here in the US too.

It sounds like you got the "Daylight" version which is a 5000K color temp and will have a bluish white light. All the Cree lamps I have are 2700K "Soft White" and they are almost too warm to my eye. I have replaced 60w incandescents at friends homes (without their knowledge) with these Cree LED's and asked them about them weeks later. The Cree lamps had been undetected the three times I have tried this experiment. Try one of the Soft Whites and see how you like that one.

Swapping out a 60w incandescent for one of these 10w Cree LED's, the bulb could pay for itself in less then a year depending on usage and electricity rate. At 4 hours per day and 11/cent kwh the saving is about $8 a year. Over the life of the LED you will save a lot more and get great light without the need to relamp every few months. If I had a stash of incandescent bulbs I's store them somewhere safe and sell them all on eBay one day.

 

[supersuds]

Oh, wow, I'd wish I'd known about the soft white! I'll look out for them, because literally the only thing I don't like is the bluish tinge.

Thanks for the tip. Nostalgia or no, none of us enjoy paying a big electric bill.

 

[whirlykenmore78]

@ kb0nes

Phil, funny you should say that about incandescent bulbs.  Holding them to sell later is exactly what I am doing with the ones I have left.  Might as well make a bunch of money off of the uninformed and those too stubborn to believe the truth about energy efficient lighting. 

WK78

 

[rp2813]

The conversion of a guest bath into our master bath should begin in about a week.  Due to clearance issues in the bathroom ceiling, the contractor has recommended LED fixtures that can be flush mounted.  I think he already knows to use soft white in this application, but I'll be sure to specify it.

 

[sudsmaster]

Flush mount lighting over toilet?

I prefer daylight bulbs in the kitchen and bath areas, and also at my desktop. Warm white for bedroom/living room/dining room/etc.

In any case, the contractor may feel the same so if you want warm lighting in the master bath probably a good idea to make sure he knows that. Also find out if replacement LED bulbs/elements are readily available for the flush mount fixtures.

 

[rp2813]

Flush mount --

Yes, in a manner of speaking.  The "flusher" will be a wall mounted model.

 

I'm concerned about replacement bulbs/elements so will be asking about that before giving final approval of the LED fixtures that have been suggested.

 

[kb0nes]

"I'm concerned about replacement bulbs/elements so will be asking about that before giving final approval of the LED fixtures that have been suggested."

In general with today's LED offerings this isn't a concern, you are quite likely to scrap the fixture before the LED module fails. I realize that many people are paranoid due to the early failures we saw with CFL's but LED's just don't see the degradation due to power cycles as the CFL's did. Relax they will last. I do suggest with buying the good name brand products though, like Philips or Cree. The off brand or re-branded stuff sold under names like Sylvania or Lights of America worries me a little more.

If you are still concerned then be sure to buy cans that use a standard medium base reflector style lamp, for these you will be able to get LED's lamps for the foreseeable future. Even with a good brand name fixture like say a Halo, a unitized LED can fixture is unlikely to have a replaceable module. They are engineered to have a ~20 year lifespan so don't count on replacement parts.

I have two 6" cans in one bathroom and I have 14w LED R30 replacements in them. The lamps flush out with with the circular trims and they look awesome, both physically and the light quality they give. I haven't touched those lights in 4 years now, not sure I will ever need to again.

 

[rp2813]

Thanks for the additional info.

 

We've gone off topic, but I want to clarify the issue I have with ceiling clearance.  This bathroom was tacked on to the back of the house in the late '60s.  I'm limited to the space provided by the rafters above the sheet rock ceiling (appx. 4"), as there is no attic space or other clearance between the roof and the ceiling.  The average recessed fixture that accepts a standard base bulb won't fit into this space, which is why I need the "slim" LED flush mount type. 

 

If this type of fixture doesn't accept replacement LED's but is easily snapped out and disconnected for replacement, I'm fine with that arrangement.