Just fired up my 1st sox lamp for the 1st time last night, and wow, I see now why some people love them.  Was curious on 2 things though...is there any danger in viewing them, like do they emit any UV or anything?  2nd what are the little silver pools for that are placed every so many inches along the arc tube? 

They don't emit any uv or minuscule amounts, it's mainly orange radiation and some ir. Second, those pools are deposits of sodium that reside in the dimples of the inner arctube.

And also keep them in good safe place, once lamp breaks.  It can react to any moister and set combustables on fire. 

The lamp is safe to look at. If it breaks, let the sodium cool down and collect it with a dry object. It will burn in contact with water (you can dispose it off safely without risk of catching fire later in the trash, by burning it in water in a controlled way)

To keep the lamp intact, dont hold it base down when it is in use or as long as it is hot and the sodium inside is liquid

They should not be moved in use or until they have cooled down after use as the sodium blobs are molten and will get all over the inside of the arc tube and block much of the light.

Just a reminder, SOX lamps (technically, most higher watt LPS lamps, such as 135w & 180w) still remain the most efficient means of light production (lumens out/watt consumed).

Just a reminder, SOX lamps (technically, most higher watt LPS lamps, such as 135w & 180w) still remain the most efficient means of light production (lumens out/watt consumed).

When speaking about the raw lumen output, yes.
But when speaking about the task to illuminate something vs the power needed for that, there are not so many tasks, where that is sufficient to really reach the lowest power requirements for the illumination task, with most applications the raw efficacy is not what would be sufficient to make the system efficient.
Their size does not allow for good and efficient optical control, so when you start to speak about consumption required to illuminate a road at certain minimum level, the higher efficiency of the beam pattern control of the HPS allows way lower power requirements.
Of course, where any beam shaping is not possible or does not work well due to other reasons (e.g. frequent fogs), then the raw efficacy does make them most efficient light source. But I doubt that is valid for the high wattage types - in that conditions closer spaced lower lumen packages would be more efficient in illuminating what is needed, so even with lower raw efficacy yield lower power requirements for the same task.
But to make such denser "pole forest" is not always possible or working, so there are applications, where even the higher wattage SOX have their place...

Yes, I generally agree that the beam pattern light control is far better w/HPS, but THAT's almost never the reason why HPS is preffered over LPS. Both the higher CRI and the fact that HPS is mass produced in "raw lumen" output sizes (600 & 1000 wattars for hi-masts) is instead. That sort of lumen output was never achieved with LPS. It's like, literally, ALL R&D departments of lighting companies completely abandoned LPS at 180W. So now we haven't got a COMPACT LPS (just like CFLs I would call it CLPS)! Can you imagine a CLPS?

Manufacturers actually had linear SOX tubes with Fluorescent lamp bases. There were some efficiency adventages - No 2 sides of U tube to hide each other (sodium vapor is opaque to the yellow light, so 1 side of the U tube really block the light made by the other), and used various no-round arc tube cross sections to minimize the length the light have to go through vapors in the same tube - The most common type was series of indents from 2 sides of the arc tube, making the dischatge go in wave like pattern

Thats the SLI LPS tubes, that came at wattages of 200W and reachewd 200..220 Lm/W efficiencies. I am not sure why but they were dropped allready in the 80s - Probably too complicated and expensive to make. Same with the >180W SOX

On the road, for high Lm packages (so no depending on low-light vision, which is optimised for moon light), high CRI is meaningless, only total light quantity counts



There is one ther advantage to large light emitter surface, which i have not yet seen weighted in

When the road is lit, both the road and the light sources are in plain view of the driver. So you have to weight in the light on the road against the glare from the directly viewed lights

The SOX with its size gives the smallest glare, so you can suffice with less light on the road as well to see well

In HID, with the advantage of better beam control, comes the disadvantage of smaller light emission area. Good HID designs can minimize the glare for the most part, and overall HPS and SOX have both equally good performance

In comparation LED, have by far the most inferior optics - They aim the light on the road most precisely (with precission that most HID  designs are not made for, and often leave dark spots in roads that were previously lit well with HID), but dont spread the surface from which the light is originating, so emit the highest glare

As the standards and performance measurements for the complete instalation only specify the Luxes (Lm / area) on the road but dont address the glare at all, they give preference to the wrong light sources.....

There are multiple reasons for abandoning the LPS:
First it is the most challenging technology in the terms of it's complexity and resulting manufacturing defects and reliability, so only very few companies were ever able to master their manufacture. The result is very high cost of the lamps. Both because they are complex, as well as there is just little competition. The HPS technology, although later, is way more robust, so there are dozens of HPS manufacturers and the lamps are rather cheap (it is still the cheapest proven light for road).
Second reason are the optical properties:
For the high masts you almost always need quite some optical control. And that to be efficient needs the smallest reflector size to be about 10..15x larger than the light source. With 10cm long high power HPS burner it means about a meter reflector, but with 50cm long LPS tube it would mean a 5m beast. Without that you will get quite a lot of light nonuniformity and light spill, so to get certain minimum illumination level you need way more raw lumens. With LPS the lanterns uses to be 2..3x more lumens than HPS for the same task. So even when the LPS has about 1.5x the HPS efficacy, the lantern for certain task consumes 1.5x more than a HPS one.
And of course the monochromatic color of LPS is very significant factor as well. It is not completely true, than the color vision is not required. "Someone vandalized my car" Police: "Describe him, what color of clothes he had?" ""


The tubes depicted have not much benefit over a single U tube. The thin format makes higher heat losses, so more of the energy is consumed to just keep the operating temperature. With LPS you consume rather fixed power for maintaining the temperature and only the rest becomes available to generate the light. Plus such complex shape would have enormous problems with the quality of the Borate layer separating the glass from the sodium (they tend to react together and form opaque brown fragile material from the glass, so keep them separated is a must)

Anyone have more info on yuandrew's post of the 90W corkscrew LPS?

The corkscrew LPS seems funny, but just like the sprial CFLs, lots of lumens are wasted.

I did think of an alternative some times before - an LPS SL* (self-ballasted low wattage LPS lamp, with internal structure based on the Philips SL* CFL). Would this concept even work?

I dont think the choke will be happy with the cooling it can get in vacuum.... Gotta place the ballast outside the outer envelope

Quote from: lights*plus on August 26, 2015, 02:55:35 AM

Can you imagine a CLPS?

I'd love to get hold of one but they appear to have all but evaporated from the (Chinese?) market.