Update - I never thought this would ever happen, but https://youtu.be/1Vjd6NmA9Hs?si=Q8FeE5m7VTbl1bv0 this video (skip to ~2:30) that dropped yesterday pretty much confirms what I suspected. James Cameron says that they went around LA with a light meter looking for streets with bright enough lighting to shoot night scenes on, and explicitly says they settled on streets lit by mercury vapor lamps.

I don't know, but I get the impression that stadiums were some of the first places to use metal halide lamps when it came to efficiency replacements, whereas most other mercury vapor lamps got replaced with HPS, since the CRI of HPS lamps is far too low for stadiums. Pretty sure some of the oldest MH lamps I've seen are stadium fixtures. Someone who's more familiar with the lighting from this time period will definitely know better than me though.

Advance RC-2S85-TP is the 120v version of the ballast posted above.

For shorter lamps and for converting existing fixtures the Universal 631-LH-TC-P is probably a better option. The OCV is lower so shorter lamps aren't as likely to instant start and the shorter ballast height means it will fit into more fixtures compared to the Advance.

Yes, I had come across that one and didn't buy it for that reason.

Detroit used to do this all the time with their series circuits, since it was easier to run regular secondary wiring instead of stringing the series circuit all the way to a pole that may sit out of the way. In this case I'm not sure why, as this appears to be a regular streetlight circuit.

When clear mercury vapor lamps are new, they tend to be a little bit bluer, once you use it for a little while it'll shift more green. As others have mentioned, there is some blackening at the ends of the arc tubes in that photo, but that can also occur if the lamp is switched on momentarily and immediately shut off, for example if the seller wanted to test it. If you let it warm up and the arc tube goes clear once extinguished, you'll know that it's new. But definitely use it for a little bit, it will turn green after a while.

@Ugly1
That is true, I guess I don't know how to read lol

 The listing says 120 volts, but the ballast label is red and says 240 volts.

@Ash
I did see different power factor numbers for different wattages, but no real trend so I just averaged them. Ideally there would be a special number to plug in for every individual lamp but I am not about to go through all of that effort lol. Ideally if you need a very precise answer for a particular lamp, you wouldn't be relying on something some stranger on the internet made, though I may or may not have done that in the past

I just used Desmos because it is what we were constantly using in middle/high school and it is just what I am familiar with. I am sure there are many more graphing calculator sites out there.

I will definitely click through Street Lights Online later today, that seems like a good source.

The lamp PF varies also by the individual lamp spec within the same lamp type. The ballast have some losses that vary by lamp type and power, and by the ballast efficiency class. Those two would further close the gap between the current calculator results and the standard specs

For ballasts here are some examples i recall (all 230V 50Hz chokes)

FL 36W T8/40W T12 :

 - ~1960s 70s ballasts : Seen 10W quoted in a book printed in the early 80s, but i think that "open core" ballasts (which production was ending around that time, but were probably still the most common in installed luminaires) may be less efficient than this

 - Standard from the 80s onwards : Typical 8W

 - Lowloss from the 80s onwards : Typical 6W

MBF 400W (used also for Halides) :
 - Seen 40W in multiple sources. Probably does not vary that much between old and new ballasts

For a fairly big set of measurements of ballasts (power consumption of lanterns or other luminaires) go to Mike Barford's site at https://streetlightonline.co.uk/ , go through the lanterns and other luminaire types in the collection



The website you used for the calculator seems to replicate some of the features of Kmplot - a local (offline) program that has drawing plots with parameters and an expression calculator