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Sideshoots - associated subjects => Heritage railway lines, Railtours, other rail based attractions => Topic started by: broadgage on September 25, 2020, 14:16:14



Title: Low pressure sodium lamps now hard to find.
Post by: broadgage on September 25, 2020, 14:16:14
Sometimes known as "sox" lamps.
The last factory making these closed last year and availability is now declining.
Mainly used for outdoor lighting, roads, footpaths, yards, car parks and the like.

If you are involved in a heritage railway, or indeed in any other enterprise that uses these lamps, time to buy a few spares, or consider alternatives.
LED retrofits are available. These are fine for everyday illumination but do not look right if an original appearance is desired.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Godfrey Tables on September 25, 2020, 17:05:21
I collect light bulbs. This is not something I thought I'd ever admit to in public, and probably puts me fairly high on the nerd scale.
A few years ago I bought a few SOX lamps, along with a means to drive them, to add to my collection.

With the way LED's are going, I don't think it'll be long before High pressure sodium, Mercury, Metal Halide and even fluorescent go the same way. Although for heritage purposes these might be easier to simulate with cleverly disguised LEDs solutions.

Some time ago at the Peak Rail heritage railway in Matlock I found gas mantles simulated with incandescent pygmy lamps. These are probably LED as well now...


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Bmblbzzz on September 25, 2020, 18:18:47
Are we talking about the yellow-orange ones? If so, I was thinking about them just the other day. That they used to be everywhere and now they're quite rare. Until a couple of years ago there were still a few streets near here with them, but now they've been replaced with (white) LEDs. For which I'm quite glad. Why would you want to replicate that colour-sapping dull yellow glow?
I collect light bulbs. This is not something I thought I'd ever admit to in public, and probably puts me fairly high on the nerd scale.
But you score highly on self-awareness!  ;) By the way, do you have a brother called Bobby!


Title: Re: Low pressure sodium lamps now hard to find.
Post by: stuving on September 25, 2020, 18:19:37
Some time ago at the Peak Rail heritage railway in Matlock I found gas mantles simulated with incandescent pygmy lamps. These are probably LED as well now...

For heritage purposes, do you want your new (sustainable?) lamp to simulate HPS or sodium, or the mercury vapour lamps that they replaced (with no attempt at simulation whatever), or the previous incandescent lamps, or the original oil lamps? Or what came before that - presumably darkness?


Title: Re: Low pressure sodium lamps now hard to find.
Post by: broadgage on September 25, 2020, 18:58:18
Are we talking about the yellow-orange ones? If so, I was thinking about them just the other day. That they used to be everywhere and now they're quite rare. Until a couple of years ago there were still a few streets near here with them, but now they've been replaced with (white) LEDs. For which I'm quite glad. Why would you want to replicate that colour-sapping dull yellow glow?
I collect light bulbs. This is not something I thought I'd ever admit to in public, and probably puts me fairly high on the nerd scale.
But you score highly on self-awareness!  ;) By the way, do you have a brother called Bobby!

The lamps that are no longer manufactured are low pressure sodium, these give a deep orange/yellow light without any colour rendering. Not normally considered to be an attractive light, but some heritage locations may prefer them in order to look traditional, they have been in general use for at least 60 years.
If the original appearance is not required, LED retrofit lamps are available.

High pressure sodium lamps, often known as SON lamps, are still manufactured and remain very popular. They give a lighter golden yellow light, this badly distorts colours but does allow some colour rendering.
I doubt that many new fixtures for SON lamps are being installed, but there is a considerable demand for replacement lamps for existing equipment.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: TonyK on September 26, 2020, 14:59:05
Many councils are actively changing sodium lighting for LEDs. Some are citing lower maintenance costs, and a 60% saving on electricity. Central government is encouraging this with grants. They are also more versatile, with some having the ability to dim at certain periods of night. All told, it looks like the end for that yellow-orange glow. I wonder if that colour, a very narrow band of the spectrum, can be emulated by a LED light?


Title: Re: Low pressure sodium lamps now hard to find.
Post by: ellendune on September 26, 2020, 19:18:06
Many councils are actively changing sodium lighting for LEDs. Some are citing lower maintenance costs, and a 60% saving on electricity. Central government is encouraging this with grants.

Swindon currently is currently 6 months into an 18 month program to change all its lights. Not only the saving on electricity but in changing lamps.  When I was last involved in street lighting (ok so 40 years ago now but the SON was the modern technology then) lamps needed changing every 2 years. 

They are also more versatile, with some having the ability to dim at certain periods of night.

Benefits of reduced light pollution which is known to affect wildlife.

All told, it looks like the end for that yellow-orange glow. I wonder if that colour, a very narrow band of the spectrum, can be emulated by a LED light?

Yes it can, as easy as white actually. AIUI colours can be produced by mixing native Red Blue and Green, but white light produced this way is not good.  Yellow and White can be better produced with a UV LED by fluorescence. The different coatings can produce a very blue white light or a yellow, mixing them allows a range of whites and if required a yellow.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: stuving on September 26, 2020, 20:13:21
Many councils are actively changing sodium lighting for LEDs. Some are citing lower maintenance costs, and a 60% saving on electricity. Central government is encouraging this with grants. They are also more versatile, with some having the ability to dim at certain periods of night. All told, it looks like the end for that yellow-orange glow. I wonder if that colour, a very narrow band of the spectrum, can be emulated by a LED light?

Depends how close you look at the light! Astronomers were relatively happy with the light pollution from the original sodium lamps, as the light was confined to the two narrow spectral lines characteristic of sodium. So while the lamps and luminaires may have been quite bad for the amount of light they chucked about, it could be filtered out within instruments leaving most of the spectrum clear for observations. At high pressures, the sodium vapour emits a broad spread of light across much of the visible spectrum that doesn't allow that to be done. Hence the astronomers were really hacked off by that change.

You can't get good colour rendering in a lamp with narrow spectral lines, so the flourescent phosphors are chosen to give the broad spread required for that - leading to more upset astronomers. And then along comes Elon Musk as well ...

LEDs are more directional, which helps, but that's a quite modest factor compared to a good filter. I don't expect we'll see the Milky Way making a return to our urban skies.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: TonyK on September 27, 2020, 00:46:00
I don't expect we'll see the Milky Way making a return to our urban skies.

One of the bigger advantages of living on the edge of a small Devon village, with a massive amount of sky available to me, is that I can often see the Milky Way. In Bristol, I couldn't often see more that a dozen stars.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Bmblbzzz on September 27, 2020, 21:09:20
In Bristol, I couldn't often see more that a dozen stars.
You just need to hang around the Hippodrome.  :D


Title: Re: Low pressure sodium lamps now hard to find.
Post by: johnneyw on September 27, 2020, 21:33:02
In Bristol, I couldn't often see more that a dozen stars.
You just need to hang around the Hippodrome.  :D

Or late night refreshment at Renato's Taverna dell'Artista....The hostelry of preference for the theatre casts and crews after last curtain....or at least it was when I frequented it all those years back.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Trowres on September 27, 2020, 22:34:23
My short road currently has one LED, 2 low pressure sodium and one high pressure sodium lamps.

BG's post has caused me to look at the nearest LP example with the same feeling I would reserve for a disappearing locomotive class  :( ::)


Title: Re: Low pressure sodium lamps now hard to find.
Post by: MVR S&T on September 27, 2020, 23:00:12
Oh, do those tall posts have a function, having only been allowed out for shopping, then going to/from work, not seen a lit street light since March, though they are stating to come on under the trees on my back from after work shopping now.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: broadgage on September 28, 2020, 00:40:06
If anyone wants a low pressure sodium lamp, these can still be found on fleabay but stocks are declining and prices increasing.
If you wish to light a low pressure sodium lamp, it is VITAL not to connect it directly to the mains, the correct control gear MUST be used, also available on line.
Low pressure sodium lamps usually have a standard bayonet cap, but this does NOT mean that they should be inserted into standard mains lamp sockets.
Most types must be operated horizontally, or nearly so.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Electric train on September 28, 2020, 20:01:29
I am not sure that SOX were that common on station platforms the colour being to close that of a yellow aspect, all the station lighting I was involved back in the 1980's was MBFU or tungsten-halogen with some rare place with plan incandescent tungsten.

LED lamps come in a wide range or colour temperatures and further colour adjustment could be done with photographic / theatre lighting gel. 

The energy saving of LED for a heritage railway could be substantial from a 40W to 100W or higher SON to 11W to 25W LED

Just as a side note the large (1960's) sliver shaded lights at Paddington station (removed in the 1990's) were 1000W MBFU and there was about 100 of them ............... I know I changed a fair few lamps and replace a number of ballasts back in the 80's


Title: Re: Low pressure sodium lamps now hard to find.
Post by: bobm on September 28, 2020, 20:26:40
Swindon currently is currently 6 months into an 18 month program to change all its lights. Not only the saving on electricity but in changing lamps.  When I was last involved in street lighting (ok so 40 years ago now but the SON was the modern technology then) lamps needed changing every 2 years. 

My area of Swindon was converted a couple of years ago.  There have been complaints they are too bright but, despite having one outside my bedroom window, I have not had a problem with them.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: stuving on September 28, 2020, 22:27:48
Swindon currently is currently 6 months into an 18 month program to change all its lights. Not only the saving on electricity but in changing lamps.  When I was last involved in street lighting (ok so 40 years ago now but the SON was the modern technology then) lamps needed changing every 2 years. 

My area of Swindon was converted a couple of years ago.  There have been complaints they are too bright but, despite having one outside my bedroom window, I have not had a problem with them.

I find that surprising. My impression (and other's comments) is that they are as bright close to, but leave unlit areas between them. The actual light source is bright if you look at it, but more directional, hence the narrower beam to keep direct light out of drivers' (and walkers') eyes. So you need more of them - which rather defeats part of the reason for putting them in. 


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Electric train on September 29, 2020, 07:24:00
Swindon currently is currently 6 months into an 18 month program to change all its lights. Not only the saving on electricity but in changing lamps.  When I was last involved in street lighting (ok so 40 years ago now but the SON was the modern technology then) lamps needed changing every 2 years. 

My area of Swindon was converted a couple of years ago.  There have been complaints they are too bright but, despite having one outside my bedroom window, I have not had a problem with them.

Many local authorities use lamps that switch to a reduced Lux level over night (I think 23:30 to 06:00 or thereabouts).  Many stations use lamps that have PIR sensors on sections of the platforms where the lamps run at reduced Lux levels and switch to the higher level when movement is detected.

I feel its peoples perception that LED lights are brighter due to the LED colour temperature range between 4500oK and 6400oK (oK = degrees Kelvin) typically SON are 2000oK and MBFU 3200oK  Normal daylight is around 5000oK.   Also as  stuving has mentioned the LED street lights are a more focused light that that offered by a SON, MBFU or SOX fitting.

LED lights have drastically reduced the levels of light pollution, I can clearly see stars in the night sky without them being masked by a hideous orange glow


Title: Re: Low pressure sodium lamps now hard to find.
Post by: bobm on September 29, 2020, 08:15:32
Many stations use lamps that have PIR sensors on sections of the platforms where the lamps run at reduced Lux levels and switch to the higher level when movement is detected.

I have been at Pewsey Station at night and seen a "wave" of light follow a non stopping train along the platform as each column detects the train.

I find that surprising. My impression (and other's comments) is that they are as bright close to, but leave unlit areas between them. The actual light source is bright if you look at it, but more directional, hence the narrower beam to keep direct light out of drivers' (and walkers') eyes. So you need more of them - which rather defeats part of the reason for putting them in. 

I was a bit surprised - but it made the Swindon Advertiser (https://www.swindonadvertiser.co.uk/news/18711616.led-street-light-brightness-row-discussed-jeremy-vines-bbc-radio-2-show/) and Radio 2!

Quote
PROBLEMS with new LED street lights shining into people's bedrooms became a hot topic on Jeremy Vine's Radio 2 show.

The Adver first covered the complaints caused by the borough council's ?6.9 million scheme to replace 28,000 orange street lights with money-saving energy-efficient LED lanterns.

Helena Williams Bowie from Penhill Drive told us about how the brighter lights were affecting her sleep and that of her light-sensitive husband John.

She then discussed the issue live on-air with Jeremy Vine and Coun Maureen Penny live on Radio 2 yesterday.

Helena said: "They were so bright it was like Wembley Stadium. The blackout curtains will be a short-term solution to an ongoing problem."

When Helena posted about her problem on a Facebook community group, she got mixed responses. One person said the lights were 'brighter than the sun' - a phrase Jeremy Vine emphasised throughout the radio segment.

Mr Vine asked Coun Penny if the lights could be dimmed and suggested that everyone misses the old orange lights.

Coun Penny replied: "We dimmed the lights in Mrs Williams Bowie's street last Friday and have undertaken further work yesterday to optimise the brightness so that it's set at a siginficantly lower rate at night time.

"I'm really sorry that she has been experiencing these problems. We have only had two complaints and we were expecting some complaints but it's important that we change over to these LED lights."

Mrs Bowie added: "It's a matter of knowing how to complain. The lights have dimmed a bit but the light is still affecting our house.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Godfrey Tables on September 29, 2020, 12:20:33
I predict that in the future, ultra modern LED streetlights would have a beam pattern that could be controlled in software.
With one LED cluster behind carefully configured optics, different parts of said cluster could be controlled remotely depending on which part of the optics are to be lit. Besides flexibility in application, any complaints about unwanted light spill, and the offending sub-cluster of LEDs could be shut off remotely, without the need of an engineer to visit with paint.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: rogerw on September 29, 2020, 17:34:22
I had a street light outside the kitchen window (1st floor) in my Trowbridge flat. With the street lighting engineer as a neighbour it was used as a trial for LED lights so that he could monitor it easily. Because the LED gave a more directed light it didn't light my kitchen as well as the previous SON unit. I have replaced tungsten bulbs in my house and, despite being  of a lower equivalent wattage, they appear brighter as the light is very white


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Red Squirrel on September 29, 2020, 18:13:59
A pedantic friend of mine refused to refer to old-style light bulbs as such; he called them 'heat bulbs'. His logic was hard to fault; an incandescent bulb converts 90% of the input energy into heat, and barely 10% into light...


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Surrey 455 on September 29, 2020, 20:36:01
Many local authorities use lamps that switch to a reduced Lux level over night (I think 23:30 to 06:00 or thereabouts). 

In my street the lights switch off completely between 1am - 5am. If you need the loo during the night and see streetlights, you know it'll soon be time to get up.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Bmblbzzz on September 29, 2020, 21:50:32
Many stations use lamps that have PIR sensors on sections of the platforms where the lamps run at reduced Lux levels and switch to the higher level when movement is detected.

I have been at Pewsey Station at night and seen a "wave" of light follow a non stopping train along the platform as each column detects the train.
Sounds entertaining! And good sense too. I've heard that some streetlamps are being so equipped but it seems to be a very rare thing so far.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: MVR S&T on September 29, 2020, 22:16:59
Got the PIR LED lights at Christchurch too thought here at Hinton Admiral the platform lights stay on all night and the footpath lights dont come on at all!


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Red Squirrel on September 29, 2020, 23:04:30
Am I allowed to wheel out my Dad's old story of returning from Pensford to Brislington one summer's evening?

5 minutes before the train rolled in, a chap in railway uniform rolled up, whistling, on his bicycle. He lit the lamps, the train stopped, Dad and his brother got on, and as the train pulled out of the station they saw the man snuffing out the lights. Most economical.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: broadgage on September 29, 2020, 23:06:05
Many local authorities use lamps that switch to a reduced Lux level over night (I think 23:30 to 06:00 or thereabouts). 

In my street the lights switch off completely between 1am - 5am. If you need the loo during the night and see streetlights, you know it'll soon be time to get up.

This is becoming more popular. It was tried in years gone by but then found little favour since a special and expensive time control was needed, these were rather complex to set and often set incorrectly.
These days, lighting for part of the night is easy by means of a "part night photocell" these are simple and require no setting up or programing.
They turn the light on at dusk, and off at midnight or such other time as may be specified, and then turn on again at 06-00, or such other time as may be specified, only if still dark.

These units automatically detect local midnight, they "know" that local midnight is half way between dusk and dawn, and of course that 01-00 is an hour after midnight.
When first put into use they turn on all night for the first few nights whilst they "learn" the time. They generally calculate local midnight on a rolling average basis as being half way between the average times of dusk and dawn for the previous week or so.
This maintains reasonable accuracy even if the light is turned on at noon one day due to a solar eclipse.

The drawback is that in most cases the times of operation cant be altered. They may be specified for whatever hours are wanted, but cant later be altered, except by replacing the photocell.
Also they calculate the LOCAL time of midnight and do not normally compensate for changes between summer time and GMT.
(A new version is under development, that DOES adjust for when we change the clocks. The photocell knowns when it is midsummer (shortest night) and also knows that the clocks go back XX days after midsummers day. It also knows when it is midwinter, and knows that clocks go forward YY days after midwinter)


Title: Re: Low pressure sodium lamps now hard to find.
Post by: stuving on September 29, 2020, 23:24:21
I predict that in the future, ultra modern LED streetlights would have a beam pattern that could be controlled in software.
With one LED cluster behind carefully configured optics, different parts of said cluster could be controlled remotely depending on which part of the optics are to be lit. Besides flexibility in application, any complaints about unwanted light spill, and the offending sub-cluster of LEDs could be shut off remotely, without the need of an engineer to visit with paint.

I suspect that exists - but deployment may depend on communications. But then soon every street lamp is going have a 5G nanocell built in, isn't it? That's not a new story, by the way - it was around before I retired in 2013 (and I had my own proposal ten years earlier for local positioning transponders...).

Here's one quote:
Quote
One of Ubicquia?s products is its Ubimetro small cell, which can be mounted onto existing streetlights. Aaron claims the Ubimetro for streetlights is a better option than deploying small cells onto new cellular poles or onto cable strands.
and here's another:
Quote
HKT is exploring the possibility to deploy small cells on lampposts. There are around 226,200 lamps in the HK Public Lighting System. Distance between two lamp posts is approx 30 ? 60 meters; typical distance is 50 meters or less. Each Small Cell / AAU covers up to 150 ? 180m in one direction.  Target is to install two Small Cells / AAUs on a lamp post. This way there is only a need to install the small cell on every sixth lamp post to achieve a continuous coverage.



Title: Re: Low pressure sodium lamps now hard to find.
Post by: TonyK on September 30, 2020, 08:41:55
I would imagine that somewhere, a line will need to drawn between cost and benefit. I am sure it will be possible soon, if it isn't already, to have lights that dim when no-one is around, self-adjust the times to match local conditions, and make disco patterns for New Years Eve. If the lighting is using under 10W of power, though, these refinements aren't saving much energy, and thus add expense without helping much.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Bmblbzzz on September 30, 2020, 10:56:01
Following on from the part night photocells Broadgage mentions, it would be clever if they learnt not only when the clocks change but which day of the week it is, so they can keep the lights on longer for the Friday/Saturday night revellers. 


Title: Re: Low pressure sodium lamps now hard to find.
Post by: stuving on September 30, 2020, 11:12:52
Following on from the part night photocells Broadgage mentions, it would be clever if they learnt not only when the clocks change but which day of the week it is, so they can keep the lights on longer for the Friday/Saturday night revellers. 

I don't know how much cleverness was specified for the lights at Wokingham station, but for the last few days they've all been on all morning (at least). And that includes most - but not all, for some reason - of the lights in Station Approach and the "north" (really south) car park.


Title: Re: Low pressure sodium lamps now hard to find.
Post by: Electric train on September 30, 2020, 20:09:55
Following on from the part night photocells Broadgage mentions, it would be clever if they learnt not only when the clocks change but which day of the week it is, so they can keep the lights on longer for the Friday/Saturday night revellers. 

I don't know how much cleverness was specified for the lights at Wokingham station, but for the last few days they've all been on all morning (at least). And that includes most - but not all, for some reason - of the lights in Station Approach and the "north" (really south) car park.

I can remember in BR days in the 1970/80s the job sheet that came out twice a year to adjust the solar time clocks for lighting at stations and depots, the time clocks did not adjust themselves for daylight saving



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