I believe it has been long established that 150W S56 HPS lamps (NOT S55) are compatible with 150W pulse-start metal halide ballasts. These two types of lamps / ballasts have nearly identical specifications. But, I have a dilemma that I need answers to:

I just recently acquired a 150W MH probe start ballast. I am pretty sure it has the same operating specifications as pulse-start, but with a higher OCV and without an ignitor tap. Theoretically I should be able to use a superimposed ignitor with this ballast to operate a pulse start MH lamp or an S56 HPS lamp. BUT, this darned 150W ballast that I just got is the dreaded CWA type *gasp*.

Now, I know CWA HPS ballasts do exist, but from my understanding they work slightly differently than MH / MV CWA ballasts. Is this stupid CWA ballast going to be a problem if I were to try and power up a 150W S56 HPS lamp on it?

Thank you!

Hmm I thought it was the other way around, S56 (150w HPS, 100v) lamps would run ok on M102 (150w PSMH) ballasts as I have a factory S56 luminaire that was equipped with a ballast rated for both S56 and M102 lamps.

I believe it is both ways, but S56 ballasts are near impossible to find so I just didn't mention it. They are both compatible with each other.

In 230V part of the world we have practically unlimited supply of 150W sodium / MH chokes + ignitor combos often given out for free. Just got a couple yesterday, that was not my intention, I wanted electronic, but could not stand for a couple of NOS pretty Tridonics with the ignitors in useful sheetmetal ballast boxes and coming in factory  sealed cartons. Cost? $3 both

Interestingly, there is no such thing as 150W probe start lamp in Eurasian part! Something very rare. Practically everything has to be pulse start. Though in Kazakhstan I got some probe start lamps in 250-400W (and sadly missed getting some 1kW purples) that certainly leaked there from China with one of Chinese specs.

By the way you can dig up some electronic 150W ballast for your MH/100V HPS lamps. Small and lightweight. Whatever magnetic Luddite idiots say
electronics run lamps BETTER!

Though your CWA will probably run S56 lamps, at least new, as well. Adventures with thermal runaway may begin when when the lamp ages but I doubt you will run this combo for years. You can verify system power at primary input, I guess you should get ~170W measured, 150W + some 20W losses. In theory, high OCV can kill a superimposed ignitor, but not very likely.

What is ANSI code of your ballast? Isn't it a M107 ballast intended to run 1.5A reduced power 175W metal halides? If so, such a ballast will run 100V 1.8A lamps, but likely somewhat underpowered.

@RRK

Yes, 150W ballasting accommodations are very common here as well, but they are almost all S55 (55V), not S56 (100V). Just because whoever made American HPS decided that 55V was a good thing.

You are correct, I won't be running this combination 24/7, I will just run it to see some HPS light every now and then. I could get an electronic ballast, but I already have a magnetic one and it should work fine for temporary use.

I don't actually know the ANSI ballast code right now, as I am away from home for the weekend, but I will check when I get back.

Sure it is pretty damn logical to have 55V lamps in US!
As you can run them right off the line using cheap and efficient chokes and a simple ignitor worth of three electronic components )

Some efficiency penalty compared to 100V lamps is probably offset by completely getting rid of inefficient and expensive leak transformers.

(unpopular opinion)

Well MH isn't 55V, MV isn't 55V, we just use autotransformer ballasts. Multi-tap autotransformer ballasts are so much more convenient for the unreasonably many voltages present in the US that HPS choke ballasts are rarely used. I just think that the benefits of making American HPS that has PSMH characteristics would outweigh the potential drawback of not being able to use choke ballasts on 120V. But I digress, it is way too late to change now.

(unpopular opinion)

Well MH isn't 55V, MV isn't 55V, we just use autotransformer ballasts. Multi-tap autotransformer ballasts are so much more convenient for the unreasonably many voltages present in the US that HPS choke ballasts are rarely used. I just think that the benefits of making American HPS that has PSMH characteristics would outweigh the potential drawback of not being able to use choke ballasts on 120V. But I digress, it is way too late to change now.

misguided opinion more like in that 55V HPS lamps existed long before any sort of low wattage pulse-start metal halide that we know of today existed, and while indeed I do find it rather amusing how as you say, there are plenty of massively bulky lossy multi-voltage HX and CWA ballasts in the US for 55V HPS lamps, I have seen my fair share of regular choke ballasts for the type, for example, one of the most popular default off the shelf streetlight's from AEL uses a choke ballast https://www.lighting-gallery.net/gallery/displayimage.php?pos=-203794


(also low voltage choke operated 100V-130V mains mercury vapour lamps, in both Medium pressure and High pressure form did exist at a couple points in history, but they never took off)

Really? I had no idea they were really used that much. Yes I know PSMH was very late, but we could have used European specs. I suppose some small advantage is had by using choke ballasts. The more I think about it, I really wish the North America had 240V live wires, then it would essentially all be the same around the world (apart from frequency).