Low pressure sodium lamp

[Don Klipstein]

Perhaps that's why I love clear HPM lamps so much. Because I was
born after they were changed. Some people find CFLs annoying. I can
practically read, write and do all my regular nightly chores under
clear HPM lighting. This kind of light makes me feel invigorated. Go
figure.

I have a little bit of a good feeling for HPM lighting at home, and I
find something invigorating about having one fired up at home.
However, I suspect it gets down to being sentimental about an old
technology that stands out as being good at a far-back time, along with
the lamps having distinct unobscured arcs. I have a bit of a thing for
unobscured arcs and glow discharges, though I often find MH "more
ordinary" - maybe because the arc tube is prone to being clouded or
discolored - or maybe because its light is "more ordinary" (4100K MH
has color close to that of "cool white" fluorescent and color rendition
shorcomings mostly similar to those of "cool white" fluorescent).
Maybe the very wierd color rendering properties of clear HPM get me in a
good mood. Or maybe I have a liking for lighting that gets wierd by
having a scotopic/photopic ratio that is very unusual for its color (clear
HPM achieves .8 while more usual for close-to-its color is at least 2).
If I light up my living room and my home work area with clear HPM, it
definitely looks "stark" but feels a little invigorating to me.
Fluorescents of most-similar-color I find "more dreary" and more
depressing, with the room's lighting appearing "dim and dreary" and
resisting improvement by adding more of such light. I seem to find 6500K
with s/p ratio 2-2.4 or so resisting "looking good" for home lighting
until something like 10,000-20,000 lux of illumination level is achieved -
and that is not usual indoor ambient lighting.

- Don Klipstein ([email protected])

 

[Andrew Gabriel]

You know, it wasn't very long ago that the City of Toronto replaced
its incandescent street lighting with metal halide (mid '90's?). It's
been thirty years since I last visited Rome, but can anyone tell me if
that city still uses incandescent sources?

Looking back at photos I took in 1990/1991 when working there,
it's all HPS.

 

[Paul M. Eldridge]

Looking back at photos I took in 1990/1991 when working there,
it's all HPS.

Thanks, Andrew. In a way I'm disappointed to hear this, but I guess
it should come as no surprise. The street lighting, albeit
comparatively dim by North American standards and horrifically
wasteful in terms of its energy efficiency, seemed "charming" in this
old world setting. I suspect walking down the Scalinata della Trinità
dei Monti under the harsh glare of HPS wouldn't be quite the same. :-(

Cheers,
Paul

 

[Paul M. Eldridge]

I have a little bit of a good feeling for HPM lighting at home, and I
find something invigorating about having one fired up at home.
However, I suspect it gets down to being sentimental about an old
technology that stands out as being good at a far-back time, along with
the lamps having distinct unobscured arcs. I have a bit of a thing for
unobscured arcs and glow discharges, though I often find MH "more
ordinary" - maybe because the arc tube is prone to being clouded or
discolored - or maybe because its light is "more ordinary" (4100K MH
has color close to that of "cool white" fluorescent and color rendition
shorcomings mostly similar to those of "cool white" fluorescent).
Maybe the very wierd color rendering properties of clear HPM get me in a
good mood. Or maybe I have a liking for lighting that gets wierd by
having a scotopic/photopic ratio that is very unusual for its color (clear
HPM achieves .8 while more usual for close-to-its color is at least 2).
If I light up my living room and my home work area with clear HPM, it
definitely looks "stark" but feels a little invigorating to me.
Fluorescents of most-similar-color I find "more dreary" and more
depressing, with the room's lighting appearing "dim and dreary" and
resisting improvement by adding more of such light. I seem to find 6500K
with s/p ratio 2-2.4 or so resisting "looking good" for home lighting
until something like 10,000-20,000 lux of illumination level is achieved -
and that is not usual indoor ambient lighting.

- Don Klipstein ([email protected])

Hi Don,

This is an interesting topic for me. I'm a bit of an efficiency nut,
so my previous home in Toronto had two foot square, nine cell, deep
parabolic fixtures recessed into the ceiling throughout (32-watt 830s
on dimmable ballasts). As my real estate agent said, it gave the
place an "institutional" feel, bit it was bright, cheerful, energy
efficient and it suited my tastes just fine, and I would argue not
completely out of place in a modern, pseudo-rustic 1950's ranch.

I couldn't get away with anything like that this time around, so I
opted for a combination of 4 and 6 inch Halo recessed fixtures with
clear, specular reflectors. The initial lamps were GE 100-watt HIR
PAR38s and Diamond Precise PAR20s. I was pleased with the overall
look and performance, but felt increasingly guilty about the amount of
energy they consumed. Ultimately, I swapped out the HIRs for 25-watt
CFLs but, to put it bluntly, I grew to hate them more with each
passing day. I then tried Philip's 25-watt MasterColour PAR38s; I
liked these a lot more than the CFLs, but they too had their colour
rendering issues and likewise lacked the "warmth", "sparkle" and
"crispness" of a halogen. Now, after all this, I'm back to the
original HIRs.

I use CFLs in table lamps (mostly 3,500K Sylvania Daylight Plus) and
they do a terrific job and seem well suited to this kind of fixture.
But when it comes to down lighting in a residential setting, there's
really nothing that can touch halogen. I wish I could be satisfied
with one of the more efficient alternatives but I'm not, and I've
decided that in this type of setting, light quality trumps energy
efficiency. However, once GE releases their HEI reflectors, I expect
these internal demons to be put to rest once and for all.

Cheers,
Paul

 

[Paul M. Eldridge]

Though I seldom get the chance to do so these days, I love running
carbon arcs. A couple of years ago I actually got to project some
nitrate film with them. Steam engine enthusiasts will tell you that
there's something almost alive about a steam engine compared to a
Diesel; carbon arcs seem rather similar somehow.

A carbon arc AND >>>nitrate<<< film?!? Clearly, this should be
accompanied by one of those "Kids, don't try this at home"
disclaimers. ;-)

You'll probably appreciate the opening titles of this outstanding
series:

Cheers,
Paul

 

[Don Klipstein]

My cousin saved this welding machine which now sits in his basement. One
of these days I am going to bring it home, because I need to add one more
spectrum to my collection: Old copper-sheathing carbon rods filled with
various salts, which were used before xenon short arc lamps for cinema
projection. These run nicely on regular welding machines.

The problem is that I don't know what these carbon rods contain. I know
their envelope is copper, but I have no idea what the salts in the core
are. Their arc gives an excellent daylight color, estimating it to be in
the vicinity of 6,000-6,300 K.

I believe this is the "white flame" carbon arc. I found a reference
saying it's 6200 K, amd usually filtered with a pale yellowish or orangish
filter to remove much of the UV and to decrease the cct to 5700 K.

I had trouble getting Google to show me what's in them. However, some
other (maybe similar) arc, known as the "luminous arc", and one electrode
is an iron tube packed with magnetite (an iron oxide) and titanium oxide.
I found a Google-provided link saying titanium was used in "flame arcs".

There is also the yellow flame carbon arc. I found a spectral power
distribution making me think sodium and calcium and a bit of thallium.
I remember (I hope correctly) seeing some of my Google attempt here saying
sodium and calcium were used in the yellow flame arc. The yellow flame
arc was said to have a cct of 4100 K.

I also saw a spectral power distribution for a mildly filtered white
flame arc. It was close enough to continuous for me to be unable to
figure out what was in it.

- Don Klipstein ([email protected])

 

[TKM]

Thanks, Terry; it's great to learn more about the marketing of this
technology here in North America. I first recall seeing LPS used at
major road crossings and interchanges in our province back in the late
'60s -- most of these fixtures have since been replaced by HPS.
Everything else at that time would have been your standard issue merc
and to a much lesser extent fluorescent (e.g., the town of Truro was
once almost exclusively fluorescent and still has a large population
in active service today).

You know, it wasn't very long ago that the City of Toronto replaced
its incandescent street lighting with metal halide (mid '90's?). It's
been thirty years since I last visited Rome, but can anyone tell me if
that city still uses incandescent sources?

Cheers,
Paul

That fits with what I remember, Paul. Toronto went through quite an
agonizing time when folks, led by an artist, tried to retain their
incandescent street lighting. I corresponded with a Toronto City Council
member at the time and we debated the pros and cons of HPS and incandescent.
There were strong citizen feelings that the "soft glow" of incandescent
wasn't the same as the organge glare of HPS. Finally, someone recommended
MH and there was a general conversion to that using 175 watt lamps as I
recall.

There was a major fluorescent roadway lighting system in Toronto too -- the
Don Valley Parkway. It was great quality lighting -- the best that I've
ever seen for driver visibility in rain; but it was expensive to maintain
and was replaced with LPS. That was quite a good conversion because the
poles were already on fairly close spacings. Other LPS systems included the
QEW through downtown and west.

I don't remember any incandescent streetlighting in Rome when I was last
there in late 2000 -- seems like it was mostly HPS at that point.

Terry McGowan

 

[Paul M. Eldridge]

That fits with what I remember, Paul. Toronto went through quite an
agonizing time when folks, led by an artist, tried to retain their
incandescent street lighting. I corresponded with a Toronto City Council
member at the time and we debated the pros and cons of HPS and incandescent.
There were strong citizen feelings that the "soft glow" of incandescent
wasn't the same as the organge glare of HPS. Finally, someone recommended
MH and there was a general conversion to that using 175 watt lamps as I
recall.

There was a major fluorescent roadway lighting system in Toronto too -- the
Don Valley Parkway. It was great quality lighting -- the best that I've
ever seen for driver visibility in rain; but it was expensive to maintain
and was replaced with LPS. That was quite a good conversion because the
poles were already on fairly close spacings. Other LPS systems included the
QEW through downtown and west.

I don't remember any incandescent streetlighting in Rome when I was last
there in late 2000 -- seems like it was mostly HPS at that point.

Terry McGowan

Hi Terry,

I was living in Toronto at that time and I recall hearing stories
about that. Correct me if I'm wrong, but in a public response to this
controversy, didn't the City set up four test streets in the Riverdale
area with incandescent, HPS and MH and ask local residents to pick
their favourite and, horror of horrors, the majority actually
preferred the HPS and not the MH that the City wanted? [Opps!]

I do remember the original fluorescent and subsequent LPS conversion
of the DVP and Gardiner Expressway and both were really quite good, as
you say. I don't know if the original guard rails are still in place,
but the base of the top rail along the on and off ramps included
fluorescent strips that shown downward to illuminated the pavement
(very cool). Unfortunately, dirt and grim and winter slush seriously
degraded their light output and they were never properly maintained.
Then, five or ten years ago, Toronto replaced the LPS lighting on the
DVP and QEW approach to the Gardiner with high mast HPS. That removed
a tremendous amount of visual clutter (interestingly, power
consumption went up, but maintenance costs went down).

Cheers,
Paul

 

[Don Klipstein]

That fits with what I remember, Paul. Toronto went through quite an
agonizing time when folks, led by an artist, tried to retain their
incandescent street lighting. I corresponded with a Toronto City Council
member at the time and we debated the pros and cons of HPS and incandescent.
There were strong citizen feelings that the "soft glow" of incandescent
wasn't the same as the organge glare of HPS. Finally, someone recommended
MH and there was a general conversion to that using 175 watt lamps as I
recall.

There was a major fluorescent roadway lighting system in Toronto too -- the
Don Valley Parkway. It was great quality lighting -- the best that I've
ever seen for driver visibility in rain; but it was expensive to maintain
and was replaced with LPS. That was quite a good conversion because the
poles were already on fairly close spacings. Other LPS systems included the
QEW through downtown and west.

I don't remember any incandescent streetlighting in Rome when I was last
there in late 2000 -- seems like it was mostly HPS at that point.

I was living in Toronto at that time and I recall hearing stories
about that. Correct me if I'm wrong, but in a public response to this
controversy, didn't the City set up four test streets in the Riverdale
area with incandescent, HPS and MH and ask local residents to pick
their favourite and, horror of horrors, the majority actually
preferred the HPS and not the MH that the City wanted? [Opps!]

<SNIP from here>

That reminds me of when I was in Philadelphia, and was eager to have my
neighborhood retrofitted from phosphored HPM to mercury-retrofit-HPS.

I was eager then! I was excited when the change occurred!

After I got used to HPS streetlighting, I wanted pretty much anything
else!

I would greatly prefer metal halide. It appears to me that
streetlighting does well when scotopic/photopic ratio is about that of
incandescents, gas mantles, or moonlight - as in about 1.4-1.8. I would
also like CRI higher than the 20's, and I really don't like streetlighting
making foliage look dark rather than reasonably illuminated greenish.
(I am aware that both HPM and HPS have low s/p ratio and low CRI, though
"deluxe white" HPM has CRI around 45 rather than 20's.)

I am starting to think that just about every 400 watt HPS streetlight is
a candidate to change to 250 watt metal halide, and every 150 watt HPS
streetlight is a candidate to retrofit with a 100 watt metal halide.
Preferably with MH lamps with ceramic arc tubes and not afraid to have
indium and thallium, preferably with rather than replacing scandium, in
addition to the usual sodium, with cct in the 3,000's. Heck, I think a
400 watt HPS luminaire could be replaced by a 150 watt MH one with
more-ideal radiation pattern, high CRI, cct in the mid 3,000's, and s/p
ratio like that of blackbody with same cct.

- Don Klipstein ([email protected])

 

[TKM]

It's interesting that they were promoted as 'new' Over here the first
low pressure sodium streetlights were installed by Philips in 1932, on
a section of the Purley Way, just a couple of miles from where I am
now. This was 25 years before I was born, and by the time that I can
remember various types of low pressure sodium lamps, SO/H, SOI/H and
finally, from the mid '60s, SOX were almost universal in this part of
the country. I think I first saw high pressure SON lamps sometime in
the early '70s, so here SOX was 'old', while SON was 'new' Now metal
halide is the 'new' lighting.

Maybe Philips considered them "new" because the design had changed somewhat.
The lamps used in Long Beach and other Philips installations were the SOX
types with U-shaped arc tubes incorporating glass dimples for uniform sodium
storage along the arc tube. There was also the novel use of heat-reflecting
films, but I don't recall if they were applied on the outside of the arc
tube or the inside of the outer jacket. The lamp design was also unique
because the lamp wattage increased with lamp burning hours, unlike the GEC
lamps. Philips promoted that since that gave the lamp light output a 1.0
lumen maintenance factor; but it had to be taken into account in energy cost
calculations and wiring designs. If memory serves, the 180 watt lamp ended
up drawing about 196 watts at rated life.

Terry McGowan

 

[TKM]

That fits with what I remember, Paul. Toronto went through quite an
agonizing time when folks, led by an artist, tried to retain their
incandescent street lighting. I corresponded with a Toronto City Council
member at the time and we debated the pros and cons of HPS and
incandescent.
There were strong citizen feelings that the "soft glow" of incandescent
wasn't the same as the organge glare of HPS. Finally, someone recommended
MH and there was a general conversion to that using 175 watt lamps as I
recall.

There was a major fluorescent roadway lighting system in Toronto too --
the
Don Valley Parkway. It was great quality lighting -- the best that I've
ever seen for driver visibility in rain; but it was expensive to maintain
and was replaced with LPS. That was quite a good conversion because the
poles were already on fairly close spacings. Other LPS systems included
the
QEW through downtown and west.

I don't remember any incandescent streetlighting in Rome when I was last
there in late 2000 -- seems like it was mostly HPS at that point.

Terry McGowan

Hi Terry,

I was living in Toronto at that time and I recall hearing stories
about that. Correct me if I'm wrong, but in a public response to this
controversy, didn't the City set up four test streets in the Riverdale
area with incandescent, HPS and MH and ask local residents to pick
their favourite and, horror of horrors, the majority actually
preferred the HPS and not the MH that the City wanted? [Opps!]

I do remember the original fluorescent and subsequent LPS conversion
of the DVP and Gardiner Expressway and both were really quite good, as
you say. I don't know if the original guard rails are still in place,
but the base of the top rail along the on and off ramps included
fluorescent strips that shown downward to illuminated the pavement
(very cool). Unfortunately, dirt and grim and winter slush seriously
degraded their light output and they were never properly maintained.
Then, five or ten years ago, Toronto replaced the LPS lighting on the
DVP and QEW approach to the Gardiner with high mast HPS. That removed
a tremendous amount of visual clutter (interestingly, power
consumption went up, but maintenance costs went down).

Cheers,
Paul

Good memory, Paul. Yes, as you say, there were some full-scale tests in
Toronto so city residents could compare the look of various light sources.
I didn't remember the preference for HPS though. My contact there was not
re-elected to City Council and so I lost track of the developments I don't
know if the lighting controversy had anything to do with the election
results

The guard-rail fluorescent systems were beautiful (Montreal had many of them
too about the time of Expo '67) and they worked well where there was little
snow and (most importantly) where the failed lamps were replaced promptly.
A stretch where some lamps were out was annoying because of the bright/dark
flashes. Maybe others know if such systems are still around. LaGuardia
Airport in NYC had one in the pick-up/drop-off area; but the largest one
that I knew about was on the San Mateo-Hayward Bridge crossing San
Francisco Bay. That installation was more than 5 miles long. It seems to
have been removed too from what I could tell driving the bridge a couple of
years ago.

Terry McGowan

 

[[email protected]]

[re: Don Valley Parkway or Gardiner Expressway in Toronto, Canada]
I don't know if the original guard rails are still in place,
but the base of the top rail along the on and off ramps included
fluorescent strips that shown downward to illuminated the pavement
(very cool).

The guard-rail fluorescent systems were beautiful (Montreal had many
of them too about the time of Expo '67) and they worked well where
there was little snow and (most importantly) where the failed lamps
were replaced promptly.

I recall seeing something kind of similar on the Kansas Turnpike (I-70)
west of Kansas City, maybe 15 years ago. The highway had the normal
concrete "Jersey wall" barriers in the middle, but there was an
illuminated strip on top of the wall, maybe 3 or 4 feet (1-1.3 m) off
the road surface. At first it looked like a really good retroreflector,
but on closer inspection (or as close as you can do whizzing by at
65 mph or 105 km/h), they appeared to be internally illuminated. It
looked like the strip was in sections maybe 8 feet (2.6 m) long, and
had some kind of lamp at one end of each section - the brightness was
good, but you could tell that it was a little brighter at one end and
evenly tapered to a little dimmer at the other end. Then there would
be a joint or seam and it would get bright again.

These were installed where there was a substantial curve in the roadway
- I'm pretty sure a couple of them were in or near Topeka. Sometime
around the same time, 3M was advertising some kind of highway lighting
product that sounded like what I saw, but I never found out if that was
what I saw.

Here in Tulsa, the city takes an "organic" approach to street lighting.
When a street-light tree gets old, its lamp burns out. The tree is left
in this condition until it is attacked by one of its natural enemies,
such as a Toyota or a Ford. The trunk then lies on the side of the road,
and almost immediately, a "bud" sprouts from the old trunk: a bright
orange cone. The bud remains in place for 1 to 5 years; sometimes the
old dead trunk is removed during this time and sometimes not. Then, a
new street-light tree grows in its place, almost overnight. That part
of the street will be illuminated until the lamp burns out, and the
circle of life repeats.

Matt Roberds

 

[Don Klipstein]

Don Klipstein wrote:

if you find any online link refs for any of those (including warmer
flames), please post them.

http://www.gutenberg.org/ebooks/17625

http://books.google.com/books?id=46NUFun4QQ0C&pg=PA72&lpg=PA72&dq="
white+flame%22+%22yellow+flame%22+carbon+arc+spectrum&source=web&ots=
oxMMngi0n8&sig=dZsh6UesHM-v2lfodp5bRzK6Xgs#PPA80,M1

Professional Lighting Handbook

Especilly pages 79 and 80. Only now I am having doubts about much sodium
being there. That peak around 600 nm makes me think of strontium, but
that also normally has a strong spike at about 460 nm, and I see only a
small one there.

- Don Klipstein ([email protected])

 

[TKM]

I find that adding a small amount of white light to low pressure
sodium greatly improves the look of the illumination. For example,
adding a two foot 20 Watt fluorescent tube to the light of a 55W SOX
lamp makes a considerable improvement to the colour rendering, even
though the light output of the fluorescent tube is quite small
compared to that of the SOX lamp.

Yes, it doesn't take much of just about any color of light -- except yellow,
of course to improve the color quality of LPS. "Blended systems" are
recommended for tunnel lighting, for example. Some of the new LED
streetlights contain various colors of LEDs so that the color of the light
output can be varied, perhaps by time of night, or to suit the character of
the street.

Terry McGowan

 

[[email protected]]

| Yes, it doesn't take much of just about any color of light -- except yellow,
| of course to improve the color quality of LPS. "Blended systems" are
| recommended for tunnel lighting, for example. Some of the new LED
| streetlights contain various colors of LEDs so that the color of the light
| output can be varied, perhaps by time of night, or to suit the character of
| the street.

Or the holiday in effect

 

[Victor Roberts]

[email protected] wrote:
[snip]

Philips make electronic ballasts for some of the smaller SOX lamps,
but I've never seen one. On 240V most sizes, I think up to 135W, can
be run with a simple choke ballast and a low-Voltage, ~700V, two wire
parallel ignitor, which is the most common type of gear these days.
180W lamps require a leak transformer, which are sometimes also used
with smaller lamps.

That's right. The principle is the same as for fluorescent tubes, with different
Wattages running sometimes on same ballasts. I think it was explained by Vic
some time ago for fluorescents. If memory serves right, the length of the lamp
determines voltage.

Correct. Discharge lamps of all types are operated from a
current source. You can connect lamps with different power
ratings in series if they all have the same rated current.
The power will be determined by the current, which is
determined by the ballast, multiplied by the voltage, which
is determined by the lamp.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

 

[TKM]

news:[email protected]...

[re: Don Valley Parkway or Gardiner Expressway in Toronto, Canada]
I don't know if the original guard rails are still in place,
but the base of the top rail along the on and off ramps included
fluorescent strips that shown downward to illuminated the pavement
(very cool).

The guard-rail fluorescent systems were beautiful (Montreal had many
of them too about the time of Expo '67) and they worked well where
there was little snow and (most importantly) where the failed lamps
were replaced promptly.

I recall seeing something kind of similar on the Kansas Turnpike (I-70)
west of Kansas City, maybe 15 years ago. The highway had the normal
concrete "Jersey wall" barriers in the middle, but there was an
illuminated strip on top of the wall, maybe 3 or 4 feet (1-1.3 m) off
the road surface. At first it looked like a really good retroreflector,
but on closer inspection (or as close as you can do whizzing by at
65 mph or 105 km/h), they appeared to be internally illuminated. It
looked like the strip was in sections maybe 8 feet (2.6 m)long, and
had some kind of lamp at one end of each section - the brightness was
good, but you could tell that it was a little brighter at one end and
evenly tapered to a little dimmer at the other end. Then there would
be a joint or seam and it would get bright again.

These were installed where there was a substantial curve in the roadway
- I'm pretty sure a couple of them were in or near Topeka. Sometime
around the same time, 3M was advertising some kind of highway lighting
product that sounded like what I saw, but I never found out if that was
what I saw.

Here in Tulsa, the city takes an "organic" approach to street lighting.
When a street-light tree gets old, its lamp burns out. The tree is left
in this condition until it is attacked by one of its natural enemies,
such as a Toyota or a Ford. The trunk then lies on the side of the road,
and almost immediately, a "bud" sprouts from the old trunk: a bright
orange cone. The bud remains in place for 1 to 5 years; sometimes the
old dead trunk is removed during this time and sometimes not. Then, a
new street-light tree grows in its place, almost overnight. That part
of the street will be illuminated until the lamp burns out, and the
circle of life repeats.

Matt Roberds

Long Beach: Low Pressure Sodium Street Lighting
I lived in Long Beach for seven years.
I recall very well the low pressure sodium street lighting used on
major roads and residential streets. The reason to use low
pressure sodium lighting was (at the time) regarded as having the
greatest lumens per Watt.

Unfortunately this was prior to considering S/P calculations should
have been used. I always wondered why; since the Purkinje shift in
human colour vision sensitivity has been know about since 1843.

At night Long Beach always seemed empty and vacant bathed with an
eerie yellow glow.

That it was and I was glad to see on a recent trip to Long Beach that most
of the LPS lighting has been replaced. The driving force for LPS, as I
recall, was a local consulting engineer that Long Beach retained to design
the installation as they tried to reduce costs. I was a technical support
person for the lamp sales folks hoping to sell Long Beach on HPS at the
time. We were doing O.K. in our efforts when the Long Beach consultant
announced that the whole streetlighting system was series wired and that it
would be too expensive to change. That made the case for LPS as series
ballasts were available. HPS lamps do not do well on series systems because
of the starting pulse requirement. But, the loss of Long Beach and several
other series-system projects prompted the development of a strange HPS lamp
that works on mercury ballasts including series types. GE calls their lamp
"E-Z Lux(R)". Light output is lower and rated life is shorter than standard
HPS lamps but it is an HPS lamp and looks like one.

I heard some years later that there was a continuing discussion about the
pros and cons of LPS involving color, crime, appearance, etc. The same
thing later happened in San Diego except that the city (through SDG&E)
actually installed some LPS, then decided to switch to HPS and installed
some of those, then went back and forth a couple of more times. It was
quite a battle.

Terry McGowan