LPS SOX Sodium Lamps

Where are you?
You should post those in the mercury thread too btw. It's long overdue a bump and I'm a wee bit away from getting some mercury yet.

Is it me or do they look like a pair of tits?

Ya, post 'em in the Hg thread =) . I don't think I'd like self balasted Hg though for the same reason I dislike incandescent lamps. Though a self balasted UVA/NUV HPHg would be cool.

I remember growing up there was one highway which was lit by SON HPS, but I didn't see a LPS outside of films. Tons and tons of HPS in use over here, even today. Pure Hg lamps are more rare now, but we used to have HPHg street lamps outside of my house growing up. We had two up here at this house as security lights but the first one died about a decade ago (before I moved in) and the last one died last year, which is why I put my SOX out in its place. Driving around now I see mostly HPS, a few SON, and a good sprinkling of Metal Halide. I mostly see MH's at car dealerships and certain car parks.

I've probably mentioned it before in this thread or the other but my eyes are hypersensitive to red light. The red emission lines in HPS/SON/MH (and the red continuum bands in low color temp fluorescents and incandescents) cause me great eye strain. Stopping behind another car with dark adapted eyes and getting blasted by their brake lights is like a punch in the face. For some reason the Sodium D line of SOX doesn't trigger this effect on me at all. I find 585-615nm very soothing. It's only below 490nm and 616-700nm that kill my eyes. I prefer very high color temp fluorescents/LEDs or SOX for any high detail work or reading (respectively) as a result.

Sigurthr said:

SON HPS
HPS, a few SON,
HPS/SON/MH

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SON is HPS. There's also variants SON-T and SON-E, the latter I believe is/was for retrofitting into mercury lanterns, but the lantern required re gearing.
(edit note 14/07 - edited for clarity as the previous information regarding SON-E was incorrect)

For some reason the Sodium D line of SOX doesn't trigger this effect on me at all. I find 585-615nm very soothing. It's only below 490nm and 616-700nm that kill my eyes. I prefer very high color temp fluorescents/LEDs or SOX for any high detail work or reading (respectively) as a result.

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I suspect the reason for the properties of SOX are as follows:

-It's not an Arc lamp, and the lamp size is large so the light is spread evenly. The best way I can describe SOX light is it just "razz sound" everywhere. It's just omnipresent which while bad for skyglow, is good for the eyes.
-The colour is nowhere near blue, which has apparently been proven to be unhealthy for the eyes.
-It's monochromatic so contrast is reduced. Reduced contrast reduces sharpness, which can be a bit trippy at first, but lower contrast gives less eye strain overall. Think bright laptop screen in dark room - contrast = hurty eyes.

One thing I noticed when we did our motorway trip is how smeary the windscreen looked under SOX. because the light is much softer and less piercing the windscreen looked much hazier than when under SON or the varying white light sources that are coming in. the slightest bit of haze or fog also shows up SOX good, and it's this property of cutting through fog that also makes it quite useful.

trencheel303 said:

SON is HPS. There's also SON-T and SON-E, the latter I believe is for retrofitting into mercury lanterns, as the lamp has an internal ignitor and can run off mercury gear.

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AFAIK SON is a type of HPS that has an enhanced spectral output, to appear more white. I was referring to the observation that we see mostly the yellower variant of HPS here, and not the enhanced type. If there was a different three-ish letter name for the enhanced white HPS and it isn't SON, then I apologize for the mistake!

trencheel303 said:

I suspect the reason for the properties of SOX are as follows:

-It's not an Arc lamp, and the lamp size is large so the light is spread evenly. The best way I can describe SOX light is it just "razz sound" everywhere. It's just omnipresent which while bad for skyglow, is good for the eyes.
-The colour is nowhere near blue, which has apparently been proven to be unhealthy for the eyes.
-It's monochromatic so contrast is reduced. Reduced contrast reduces sharpness, which can be a bit trippy at first, but lower contrast gives less eye strain overall. Think bright laptop screen in dark room - contrast = hurty eyes.

One thing I noticed when we did our motorway trip is how smeary the windscreen looked under SOX. because the light is much softer and less piercing the windscreen looked much hazier than when under SON or the varying white light sources that are coming in. the slightest bit of haze or fog also shows up SOX good, and it's this property of cutting through fog that also makes it quite useful.

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I and others have suspected the above, but my experimentation and experience shows two examples which would go against this hypothesis:

1) When looking at a diffuse light source (light reflecting off of a matte white wall with the light source behind me and completely occluded from view) I notice no difference in my perception of the light intensities and sensitivity from what I described earlier, which would suggest that it isn't merely an irradiance issue.

2) Note that while the blue light hazard is certainly an issue for eye health, the higher color temperature rich-in-blue-light fluorescent lamps don't give me eye strain where as the common "warm white <5000k" fluorescents DO give me eye strain rather quickly. All fluorescents are diffuse light sources as they are not (pseudo)point sources or high intensity discharge lamps.

I've come up with two hypotheses which would explain the difference in my perception of light, but they are just that as I cannot objectively test or prove them. 1) My green (and possibly blue, but to a much lesser extent) photopigments are somewhat less sensitive than they should be, thus green/blue-centric light appears less intense and jarring. 2) The peak response wavelengths of my photopigments are shifted outwards from the normal range. This is supported by the fact that I can see 340nm-840nm and the normal established average range is something like 380nm-820nm, and that the yellow range is mostly perceived by the green cones.

Sigurthr said:

AFAIK SON is a type of HPS that has an enhanced spectral output, to appear more white

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You're thinking of white SON. SON is just what the british call standard high pressure sodium, as far as I know.

Aha, thanks for the clarification and correction, Cyparagon! I suspected that may be the case after Trench's post. Guess I'd been using the term wrong, woops!

Interesting, I've never heard of white HPS. I googled and it looks to be a predominantly American thing, I'm guessing because you guys always did favour white light. Here in the UK we are also starting to favour white light (again) and one of the new lamps on the market is Cosmopolis, which is a form of compact ceramic metal halide. Unlike LED or fluorescent the white light is creamy with a warm, slightly peachy tone. It's actually very pretty.

CosmoPolis - Philips

Its a small town here but here are the 4 types of street lighting here. Not sure if they are all sodium or not. I am sure that someone here will know what they all are!
These first two are a whitish colour.



The next two are of a yellow colour.

Put a diffraction grating up to your eye (or in front of a camera) and check.

@ busman, the "diffraction grating" you use can be anything that splits light. I use bits of cut up CD that I stripped the top layer off. As cyparagon says, put it in front of your eye and look off to the side of the light source and you see its emission lines. "Normal" light sources are an underwhelming mix of red, green, blue, but something like HPS reveals its prominent emission lines.

I just did it with one of our street lights:


A lot of that is actually from the mercury, the yellow/orange is sodium and so is the turquoise one. No Argon in these lamps but under higher pressures sodium emits this line as well as the D line.

I find the best way to see the lines is to counter intuitively focus (your eyes or camera) at infinity. If you try to focus on the disc, you won't see the emission lines themselves, just the blur of colours. The above is a heavy crop from a DSLR, but anything with a few megapickels and up will do, even an iPhone, to just see the lines.

@Cyparagon. Thanks for the tip, would never have known.:thinking:

@ Trencheel. A detailed explanation there. I will certainly go and try this tonight and see what sort of lights we have here. There are a few "Normal" type lights in town but most are like in the photos. Thanks for this, it will be most helpful.

LPS will show only the two yellow Na-D sodium lines when fully warmed up. HPS will show as above (the turquoise, Na-D yellows, and red continuum are from the sodium, the rest are Hg lines). HPHg-White will show violet, blue, a strong green line, and a red continuum from phosphor coat. HPHg regular will have the above but a stronger 435nm line and instead of a red continuum there will be a line in the deep red around 700nm. The lack of red lines is typically what gives HID lighting a cold feel and low CRI.

@ busman
I try not to do too much guesswork on these subjects (because it often ends up being wrong!) but in this instance I'd wager a fair bet the first picture you posted is a mercury lamp. It's got that characteristic green look going on that happens to mercury when it's getting to the end of its life, and since it's dayburning it's probably pretty tired.

I mentioned earlier that I have hardly seen any mercury, but since I started to pay attention I've noticed a surprising amount of it in the town here. I'm about to bump the mercury lamp thread (which I've been dying to do for ages ) with my findings.

I've also been thinking, since the thread has sort of changed direction maybe we could rename it. Something like, "Sodium lamp discussion", as we're no longer talking about purely LPS lamps. What do you think, Sigurthr? It'd be a shame to split the thread, as although we've gone off topic I feel the discussion has still flowed well. Entirely up to you as thread owner, just a passing thought.

I don't mind putting an addendum into the title to allow HPS officially. No problem.

I'm doing some work on LPS related stuff today as it so happens. I received the ballast and bayonet socket in the mail today. Now I'm just waiting on the lamp itself. Since it is impossible to source genuine LPS ballasts here in the US we are forced to be creative and use Fluorescent ballasts. The Fulham company makes some excellent electronic ballasts which when selected correctly will happily run LPS for years.


https://www.youtube.com/watch?v=aREgcyL1ZoY


Edit: looks like I am unable to edit the thread title, perhaps it is too old and can't be changed? I thought you just have to click on the space next to the title on the forum screen. At least I seem to remember doing it that way.

I thought so too, it might be that the thread is old. Perhaps a moderator can do it.

I've heard about running SOX on fluro ballasts and if the right one is selected it apparently does no harm as electrically they're pretty much identical. Assuming they don't cost a fortune it's probably more cost effective than having a magnetic ballast and ignitor shipped from over here.

OOI I just took a look at the spectral lines of my small SOX lamp. It's been on a few hours and the lantern canopy is nice and hot now, the lamp isn't as monochromatic as I'd have thought. There are two or three cyan/turqouise lines, too weak to make a difference but they are there.

Yeah, SOX lamps use a penning mixture to vaporize the sodium droplets. It's a mixture of neon gas and other trace. As the partial pressure of the sodium rises the other lines fade off. It'd be curious if you're starting to see HPS lines though, even faintly, as this would mean the pressure in that tube is quite high. My 35W LPS lamp shows some very faint lines at ~490nm, ~540nm, ~560nm, and ~630nm. The 543nm and 632nm are Neon lines but the ~490nm and ~560nm I'm not sure about. The ~490nm is probably the turquoise we see in HPS, but I don't remember seeing anything near 560nm in a HPS. It could be another Neon line or a line of some of the penning trace or getter.

I'm having a hard time tracking down the operating current for an 18W SOX. Some places say anywhere as low as 250mA and others as high as 340mA. If this little pony ballast doesn't do the trick I'll have to pick up the next model up (Fulham Workhorse 2) which is well known to run them perfectly. The Pony was only $8, but the workhorse 2 is 3x that. There's no real harm in underdriving a LPS SOX lamp of this wattage either, it just won't be running at full brightness, which for this given application may not be a big deal.