What I’ve noticed, is that metal halide lights are WAY less common than HPS or mercury vapor offerings for city-owned streets. I was never sure why. Metal halide puts out a much better light quality than HPS. MH is my favorite HID source and I wish they became standard on streets rather than HPS. I’m not a fan of clear mercury either but I even like those better than HPS.

I get that they don’t last as long as MV or HPS, but they look good and they actually are a white light. MH NEMA heads and MH coach style lanterns or UFO style post tops also seem rare. Now, LED has taken over, and quality LEDs have even better light quality than MH. HPS made visibly on roads worse, and they also were a very warm color which wasn’t the most appropriate for a street.

The only time you’d find an MH cobra or post top was in cities that refused to use HPS (like Charleston, SC) or in upscale parts of a city. MH NEMA heads are pretty much non-existent, and only Cooper made them.

Shoeboxes, floodlights, decorative teardrop lights, and acorns seem to be an exception, as they’re all common in MH. Wall packs, bay lights, grow lights, and recessed cans don’t count as they’re not street lights.

Because they have lower efficiency and frequently explode at EOL. Just imagine maintaining thousands upon thousands
of MH fixtures. You will need many more spare parts for all the shattered refractors and dented reflectors.

Conventional probe start MH, especially when operated horizontally in a cobrahead tended to perform pretty bad compared to MV or HPS in terms of lamp life. There were some horizontal probe start lamps developed with curved arc tubes but they required special lampholders to allow for the proper orientation so they weren't that common.  Pulse start and CMH was a bit better but by that time most cities already converted to HPS and only opted to use those systems for upscale areas with higher budgets.

Toronto used quite a bit of MH in the older parts, a lot of streets used MH gumball luminaires ranging from 70w to 150w replacing incandescent gumballs in the mid 90s. They tended to use dual arc tube pulse start quartz lamps to get better lamp life and the gumballs had vertical lamps which worked better than cobraheads. There were some cobraheads and decorative MH luminaires with horizontal lamps, but they weren't as common as the gumballs.

I’d say @joseph_125’s statement pretty much summed up why MH wasn’t really used around here either. They were expensive to maintain and operate, so they were often reserved for special situations, such as downtowns, business districts, private developments etc. where aesthetics/better color rendition were desired.

Meanwhile had CMH come out much sooner for roadway use, we may have seen it more widespread as those did negate some of the disadvantages of conventional MH lamps, while offering better efficiency and improved color rendition. However it was simply too late, the writing was already on the wall because of LEDs.

Philips did try to sell them. The Citywhite or Cosmowhite or whatever they called it, can be swapped straight into SON compatible fixtures. My old neigborhood actually has one single HID lamp swapped into an entire neighborhood of HPS lamps. Why? No clue. Installer probably was one lamp short for a group relamp and reckoned no one will bother complaining about it. Alternatively one rolled into the box of tubular HPS lamps and it didn't get noticed until it was screwed in. The arc tube obviously looks very different to a SON arc tube, but maybe the guy thought 'Heh, (...) it, it is the final couple of years for this installation, let's see if anyone notices'.

I have two of them, and although it works on my HPS gear completely fine, i don't have an explosion-proof fixture.

We have and had so many SON fixtures, but i know only of the city of Groningen, on the Vestdijklaan, that actually seemed to use HID for public street lighting (except for an art project in Den Haag that used blue HID lights as the sole form of street lighting, giving the same impression as purpled out LEDs).
I delivered mail there, and i stared into those lanterns a lot of times, wondering about the cool white light and what kind of lamps those could've been, since LEDs were large panels, and SOX was never cool white. It was right at the start of the big ledification push, in 2020-2021. It was too bright and too much of a point source for LED so after a while i concluded MH
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Private lighting projects used HID slightly more often, buildings and walkways on commercial terrain were more often lit with HID or fluorescent than with HPS. If they haven't been removed by now, under the highway overpass where an Albert Heijn is located in Zaandijk (under the A8 highway) there are a bunch of HID flood lights lighting the underside of the overpass to make it more attractive to people shopping there.

EDIT: i think there actually is another HID installation still running in my city, either that or only a few SON's relamped with MH - Cornelis Bruijnzeelweg near Hornbach DIY store. I will verify next time i am there.

We did have some Philips CosmoPolis lamps migrate to the US. In fact one manufacturer, AEL, offered a 325 series luminaire that was equipped with compatible CMH components for them. The only city that would adopt CMH in a significant scale was Chicago, however they only used them in portions of the city and ultimately never did a total conversion. Pasadena, Calif. meanwhile did install a small group of CMH in their old town business district, but that was a one-off occasion.
 

MH lamps generally have shorter life than HPS and MV lamps.

That is correct…

I’d say @joseph_125’s statement pretty much summed up why MH wasn’t really used around here either. They were expensive to maintain and operate, so they were often reserved for special situations, such as downtowns, business districts, private developments etc. where aesthetics/better color rendition were desired.

Meanwhile had CMH come out much sooner for roadway use, we may have seen it more widespread as those did negate some of the disadvantages of conventional MH lamps, while offering better efficiency and improved color rendition. However it was simply too late, the writing was already on the wall because of LEDs.

Metal halide is less expensive to operate than mercury vapor. Mercury vapor is significantly less efficient than metal halide (but not as efficient as HPS). But yes, they are more expensive to maintain and they don’t last as long.

Also, MH lamps don’t usually fail violently except for low wattage PSMH lamps (some do, though). They were found a lot in business districts, private developments, and on and in businesses for a long time. They weren’t usually even found in subdivisions, mainly like on the outside of apartments or something like that, and if used, they weren’t normally cobra heads, they were shoebox lights or acorn post tops.

Also, CMH cobras are even rarer than QMH cobras in most cases.

Also, we don’t need every MH lamp to be CMH, and not all MH lamps explode (it’s not extremely common for most variations). Probe start lamps tend to actually explode less than PSMH lamps (especially PSMH lamps ranging from 50 to 150 watts). Ceramic metal halide is expensive and they often don’t last as long as HPS (many have similar lifespans to standard PSMH pulse start lamps), though I’ve seen some go up to 24,000 hours, and Chicago, IL had so many failures with the CMH fixtures, so that was an issue too. If all cities went to CMH, they’d pay a LOT of money just to replace them because the lamps are highly expensive (especially higher wattage ones), and I don’t think cities can use 100W CMH for all their lights, some parts would require 250W or 400W lamps to get sufficient brightness. You can’t use 100W CMH for a highway.

In general, electronic HID ballasts seem less reliable than magnetic ones (kind of like fluorescent ballasts), and many CMH lamps require an electronic ballast. If cities used probe start for street lights, it’d be just fine, they may not last as long, but cities used incandescent street lights at one point (which had significantly shorter lifespans than metal halide).

Nowadays, there is no point of using MH or CMH as street lights as we already have LEDs which are more efficient and last longer than MH, and have a comparable or better CRI. I actually like that the LEDs are full cutoff, as that design puts the most light on the road and sidewalk, and the least on the sides and up. I like 4000K the best for street lights (though I prefer 5000K for anything else). LEDs probably last longer than MV if properly designed (because LEDs do not experience the same lumen depreciation as MV normally). The primary issue with mercury vapor was that over time, they’d get dimmer and eventually they’d get so dim that they’re only as bright as a 15W incandescent. LED lights also cannot explode.

@Lightingeye60 - AEL made CMH/PSMH NEMA-heads in 70W/M98 (C98), and 150W/M102(C102)...

PSMH was quite common in SC, they were used as alternatives to mercury vapor lamps.

Maybe AEL did at one point, but the AEL PSMH nemas must’ve been short lived, since when I view their latest spec sheets for those they only show HPS.

Not all CMH has worse efficiency compared to HPS especially european ones like Osram HCI 4y serie and some Philips CDO, as far I know HCI-TT 250W 830 4y has quite similar light output as 250W SON-T PiA Plus from Philips, higher CRI and a bit higher CCT also will be brighter for human eye than HPS light even with same lumen or a bit less.
About durability, CDO-TT and HCI-TT especially these from older productions has tend to lasting around 7-10 years in street lighting

Yep, this explains why Metal Halide cobra's weren't all that common. My city has encountered Metal Halide Cobra's randomly popping up from time to
time... lighting up apartment parking lots, lighting the entrance to neighborhood roads, randomly lighting back roads... I still keep seeing them, to
this day. I can understand why they weren't so common, as bright as they temporarily were... some of them failed early before getting replaced with LED's
street lights.
There is one near me that is still lighting the entrance to a neighborhood, but it does appear to be getting dimmer, though it does not appear to be
greening out yet.

Do you prefer metal halide cobra heads or mercury vapor/HPS cobra heads?

What is your favorite light source to find cobra heads using?

@Lightingeye60 No utility around here really cared about lumens per watt to a certain extent. They cared about whether or not they would have to be back in a year or two to replace a rapidly lumen depreciated bulb. Metal halides are crap when it comes to life. they are the worse out of the bunch. MV lasts eons and good HPS has also been known to last a while. less maintenance = less cost. They let the mercury vapor lamps go until they die here.


As for the LEDs lasting longer than MV..... eh doubtful. Unless it is the little red indicators in a power strip or a dim white LED in a night light there is basically no chance of them hitting some of the rediculous hour times MVs have hit. Too many electronics and too complicated of a device that is being driven HARD to create such light. Realistically the MV lumen depreciation is not a hard and fast rule. some depreciate in a year and some take 15-20. The westinghouse in the bucket light at my mothers house has not depreciated noticably at all, still glows pinkish white and starts deep pink. and is now 10 years in use.