It used to be European choke style ballast were marked for only mercury vapour, or halide, or HP sodium. I keep finding newer ballast marked for either HPS
or Halide use and even Mercury Vapour or Halide. This would suggest any of these ballasts can run HPMV, MH or HPS lamps of the same wattage. Some how I doubt
this is a good idea. I know there is an argument that older HPMV ballast may fail with igniter pulses, but I would think a HPS would under run on a HPMV ballast. Have lamps or ballasts changed over the years?

It used to be European choke style ballast were marked for only mercury vapour, or halide, or HP sodium. I keep finding newer ballast marked for either HPS
or Halide use and even Mercury Vapour or Halide. This would suggest any of these ballasts can run HPMV, MH or HPS lamps of the same wattage. Some how I doubt
this is a good idea. I know there is an argument that older HPMV ballast may fail with igniter pulses, but I would think a HPS would under run on a HPMV ballast. Have lamps or ballasts changed over the years?

I've found it depends, which probably doesn't help much..!

Some MH and HPS lamps can run on the same ballasts,I have 35W and 50W lamps of both types that will, but I don't think I'd put them on a mercury ballast. With higher wattage lamps it gets interesting. I have two 250W ballasts, one claims to be able to run MV and MH lamps at 2.13A and the other says it's for HPS and MH at 3.0A. So unless 250W MH lamps come in two current ratings, it's confusing and I'm not sure which one to use

At times like this, I envy the US ANSI ballast numbering system, where you know a 100W mercury lamp uses an H38 ballast, it's marked on the lamp packaging and often the etch as well. Unlike here, where it sometimes seems like a guessing game..! I just wish US ballasts looked a bit less like an explosion in a wire factory 

At times like this, I envy the US ANSI ballast numbering system, where you know a 100W mercury lamp uses an H38 ballast, it's marked on the lamp packaging and often the etch as well. Unlike here, where it sometimes seems like a guessing game..! I just wish US ballasts looked a bit less like an explosion in a wire factory 

There is also H44 for 100w lamps but a lower arc voltage higher current kind! Really there is some good deal of repeats and confusion that you have to look out for, But ballast codes where mostly fine till venture attached with there oddball wattage lamps, that muddled up the numbering for a bit! So if your a silly american like me, you have to sort of catch the small hiccups in the system, and know what you can substitute out if need bets will have to do. .

Once the explosion happened, we could never get all the wires back in place so our modern ballast  desing is what it is

I wasn't aware of the difference between H38 and H44. I've seen lamps marked for both, but wondered why. The PAR38 mercury lamps we have say H44 I think but H38 lamps seem to work on the same ballast. The Blak-Ray lamp ballast is potted in about a ton of tar, so without digging I've no idea which type it is

Yeah, that's what I've seen too, the 250W seems to appear in  HPMV/MH or MH/HPS versions 1kW & 400W in HPS and MH versions.

So how are you supposed to know which current rating your MH lamp is..? I don't think I've ever seen it marked on a lamp package, are you supposed to try and find the manufacturer's data sheet every time

One thing I've noticed with MH ballasts here was that all the probe start ballasts used to be marked with the ANSI code for the same wattage mercury lamp but due to the mercury ballast ban in 2008, all references to mercury vapour like the ANSI codes have been scrubbed from the ballast labels and literature, even though the part number for some of these ballasts haven't changed.

I don't know how it is over in Europe, but for wattages with more than one ANSI code, one is often more common than the other.

H38 is more common than H44 (100w mercury)
H36 is more common than H34 (1000w mercury)

S55 is usually more common than S56 (150w HPS)

A side effect of the ANSI code system is that most literature for lamps sold here unless you dig into the lamp engineering bulletins omit the lamp voltage and current and just specify the ANSI code instead. 

Well , what bugs me is the fact that previously, there were ballasts specifically labeled  "for H-36 MV" or "for M-47 MH" only.
Even the lamp catalogs said to run lamps on their specific ballasts ONLY ! I believe that the ballast manufactures simply combined rating that were "close enough" so they wouldn't have to stock all of the different  ballast ratings .

Well , what bugs me is the fact that previously, there were ballasts specifically labeled  "for H-36 MV" or "for M-47 MH" only.
Even the lamp catalogs said to run lamps on their specific ballasts ONLY ! I believe that the ballast manufactures simply combined rating that were "close enough" so they wouldn't have to stock all of the different  ballast ratings .

Yeah, that's what I suspect too. Must play havoc with MH colour temperatures and lamp life expectancy. Efficiency of lamp and ballast must be compromised too.

When a MV ballasts are proved to run a MH lamp then the ballast has an additional thermo fuse incorporated for the case the MH lamp would rectify and overheat the ballast and this thermo fuse is mostly only in newer ballasts.

I’ve learnt that some eol conditions of a MH lamp can be very harsh for a reactor ballast. MV and HPS are usually not a problem.

Some MH lamp types like the HQI from Osram are meant to be run either on 3.5A of a MV ballast or HPS ballast at 4.2A. On MV the light output and CCT is lower than on the HPS ballast. The newer Philips HPI Plus is also designed for MV or HPS.

Yeah, that's what I've seen too, the 250W seems to appear in  HPMV/MH or MH/HPS versions 1kW & 400W in HPS and MH versions.

When a MV ballasts are proved to run a MH lamp then the ballast has an additional thermo fuse incorporated for the case the MH lamp would rectify and overheat the ballast and this thermo fuse is mostly only in newer ballasts.

I’ve learnt that some eol conditions of a MH lamp can be very harsh for a reactor ballast. MV and HPS are usually not a problem.

Interesting, I'll watch out for a thermal fuse, although it's probably well buried in the windings. I have have old SON lamp which can be nasty to ballasts. It quite often spends 3 or 4 seconds behaving like a diode when first switched on. Sounds really angry on the ballast and can take the mains fuse out if neatly rated. It does settle down, so I guess the ballast only has a few seconds to deal with the overload.

I may have maybe a defective Philips BSN MK4 ballast which I can open and show you the fuse. Since it is for also for designed for CMH/MHN it is also has a fuse built in and the MK 4 are notorious for failing suddenly without a trace of burning or so.

Interesting, I'll watch out for a thermal fuse, although it's probably well buried in the windings. I have have old SON lamp which can be nasty to ballasts. It quite often spends 3 or 4 seconds behaving like a diode when first switched on. Sounds really angry on the ballast and can take the mains fuse out if neatly rated. It does settle down, so I guess the ballast only has a few seconds to deal with the overload.

Well , what bugs me is the fact that previously, there were ballasts specifically labeled  "for H-36 MV" or "for M-47 MH" only.
Even the lamp catalogs said to run lamps on their specific ballasts ONLY ! I believe that the ballast manufactures simply combined rating that were "close enough" so they wouldn't have to stock all of the different  ballast ratings .

Hmm aside from a post 2008 ballast, I don't think I've seen a pre 2008 MH ballast that didn't list the MV ANSI code too. My understanding is that the MV and MH ballasts in the 175w to 1kW range are basically the same but the MH version had a higher OCV to start the MH lamps and the lamp current was close with MH probably having tighter current regulation. 

Just looked at the rating for a 1kW MH/HPS ballast 10.3A-HPS 9.5A-MH. Don't think I could trust in with a MV only pulling 7.6A