As for why you are getting high voltage across the capacitor and inductance, that is the way series resonant circuit works. You still have (not accounting for actual distorted non-sinewave current!!) U=I*impedance (of an inductor or capacitor) but the voltage across the whole circuit is low as these voltages are about 180 degrees out of phase and largely cancel each other.

Have a good read here: https://en.wikipedia.org/wiki/LC_tank

I bet that rough explanation of how these circuits work is while this kind of ballast has low impedance at fundamental 60Hz, inductance value is high enough to store energy available to fast transients like discharge re-ignition. In harmonic way of thinking, ballast impedance is low and capacitive at 1st harmonic, but high and inductive at higher harmonics.

Next, you are doing a few things wrong -

You are probably getting strongly distorted voltage and current lamp waveforms in your circuit. So you can not measure them properly with a regular multimeter, you need true RMS one. More, the product of multiplication of even true RMS voltage to true RMS current will not give you a proper power value for signals of non-sinewave waveforms and also unknown phase relationship.

That's the area where oscilloscopes belong to.

I have quite a large collection of Japanese HID lamps which I bought from Japan. Many of them are mogul base.

I've noticed that the 200w and 250w lamps use either a bt28, ed28 or bt32 outer envelope. However, those envelopes have a neck that is longer than a standard bt28 or ed28 lamp.

I think the reason for this is they will fit better in fixtures designed for 400w bt37/ed37 lamps without adjusting the optics. Another reason could be the short neck bt28 or ed28 lamp would not fit because the neck is too short.

This seems to apply for many of their fixtures like floodlights or streetlights.

I have found documentation of fixtures listing wattages of 110-400w HID: Floodlight, Pole Light, Cobrahead

The 110w refers to an HPS or CMH lamp with a mogul base and a bt28 long neck envelope.

As far as I know, I haven't seen long neck bt28 or ed28 HID lamps used anywhere else other than Japan.

 I've seen a few different ways around this .  Not using the word Incandescent in the listing , spelling it wrong I.E. Incande$cent , No LED , Old Style light bulb , ETC.

Yes, they have a neon-argon penning mixture gas to facilitate starting on probe start metal halide ballasts without the need for an external ignitor.

and also, Philips’ CDM330 AllStart ceramic metal halide retrofit lamps

Are these compatible with probe-start ballasts?

Note: I am in the USA, so 120V 60Hz. Also this post is really long so, sorry in advance, but if y'all can help that would be super great!

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PREFACE:

Normally if you are using an inductive choke ballast for any type of electric discharge lighting, the supply voltage has to be (approximately) at least twice the running voltage of the lamp. But, if you use the right capacitor in series with the right choke, this requirement is somehow bypassed(?). I hear this is called semi-resonant. I am sure many of you have heard of this, like in those cheap Lights Of America shop lights.

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THE EXPERIMENT:

I recently powered an F40T12 rapid start lamp with a .2H choke and 2.5uF capacitor in a standard preheat configuration with a manual starter switch. The lamp lit beautifully (with some initial striking problems), even though the arc voltage of one of these is supposed to be 100V (way more than half of 120V). The circuit drew .455A, which would suggest that the lamp was overdriven, but the lamp was still quite dim (we'll get to that later). I posted a picture of this lamp lit connected to this circuit in my gallery:
https://www.lighting-gallery.net/gallery/displayimage.php?album=8574&pos=0&pid=255553

The following circuit was made (excluding the starting preheat circuit):

Hot--(A)--{.2H CHOKE}--(B)--{2.5uF CAP}--(C)--{F40T12 TUBE}--(D)--Neutral

I also made a to-scale paper schematic drawing with physical distances representing voltage differences (also with voltage labels):

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QUESTIONS:

My questions are as follows:

1: Cap and choke voltage
How is the voltage across the inductor and capacitor so gosh darn high if the supply voltage isn't? I know the phase angle of them makes it all add up to 120V in the end but what is making it do that in the first place? Nothing about this makes sense.

2: Tube voltage:
How is the voltage across the tube only 37 volts? This calculates to around 17W, which explains the dimness of the tube. How is the tube being overdriven by a few milliamps but still managing to output less wattage?

3: HIDs?
Could this concept be used with HID lighting? I am thinking of trying it out but I am not sure if it is a good idea.

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Thanks for reading this whole darn thing, I know this is a lot to ask, but maybe someone can help me out. I tried as best as I could to make this easy to understand, but let me know if you need any clarifications. I think this is an interesting thing for us to investigate, especially for the people like me who live in 120V countries. Thanks!

What are the new ones?

@Baked bagel 11 Yes I have. Most of my collection is stored at my parents factory but will eventually come to the new house once my new work area is ready. At the moment, it's being used to store the lawn mower, some of my dad's motorbikes and a few garden tools.

Man, It should be the other way round- LEDs get banned and Incandescent get to be sold. I have no clue why are they trying to get rid of these incandescent bulbs even though they have no mercury + toxic gases in them. The only thing what I see a negative in them is that they get very hot and maymelt if current gets too high. Otherwise, these nasty things should be