Interesting, it's a HX-NPF ballast instead of a CWA. Might be useful for some NEMA head conversions.

this may have lit a Mh fine when It was installed. Some MH lamps start easier on MV ballasts. I've gotten 175W MH Sylvania lamps to light in my M-250R1 but most of the time i need to turn it on and leave it alone. One electrode will glow blue on the end for like 15 minutes then the lamp will start flashing and then it'll make an arc and start up. out of the 3 NOS Sylvania 175W lamps (from the same batch), one will usually start right up, one will do that thing i described, and the other won't do anything on the M-250R1's ballast no matter what. (it's a 120X240V CWA, though for some reason GE labeled their 120X240V CWA ballasts as "regulator" ballasts, as my M-400, M-250R1, and the spare 1966 175W 120X240V ballast all have "REGULATOR BALLAST - NOT FOR ORDERING".

I've always prefered HX MV ballasts over CWA since they're smaller and simpler, meaning they're more universal, cheaper, and don't have a cap that can fail. It's annoying that only multivolt CWA replacement ballasts are made for MH and PSMH lamps and for >150W HPS because often with fixtures, multivolt ballasts don't fit because the original ballast is a single tap reactor or HX.

Yeah, some MH lamps will start when new on a MV ballast but as the lamp ages, the starting voltage goes up and starting gets iffy on a MV ballast. It seems probe start MH is a bit iffy to start though, I have a 175w on a MH ballast that always takes a few seconds to strike even though both lamp and ballast are basically brand new (I probably have ran both for 24 hours total at most).

It seems that ballast makers have trimmed down their ballast offerings too, it seems back in the day 175w MV ballasts were offered in 240v reactor, 120v HX, 120v CWA, multitap CWA, multitap CWI by most companies but as the ballast ban drew closer only multitap CWA MV ballasts were offered.

In fact I think even with MH and HPS, the choice of ballast is pretty limited, with HPS you usually get 120v reactors or a multitap HX for lower wattages. For higher wattages multitap CWA is basically all you can get.

Same with MH too, lower wattages are HX multitap while high wattages are multitap CWA. I never had a problem with replacement ballasts not fitting though but I guess it's usually because I downsize the wattage when replacing a ballast to save energy and to lower the lumens.

yeah even PSMH lamps have trouble starting a lot too. sometims nothing happens for like 30 seconds.

Ahh, my PSMH lamps usually strike instantly like mercs and HPS but I've had the delay for probe start lamps.

I have a few 400w MH lamps (probe-start) that take awhile to start...the ballast will sit there buzzing then there'll be an "arcing" sound then the lamp lights. The 400w Philips I'm currently using (Which is rarely at that; I don't need that much light and it draws too much power anyway) starts right up though as soon as power is applied.

I've seen plenty of pulse start ballasts not strike up new lamps right away, one took 4 minutes! Usually they come on right away though, if they're slow I would say the ignitor is on its way out

i don't know if it has to do with the igniter. With my two M-400A2s, they both have ED28 320W PSMH Philips lamps and one lamp starts right away regardless of which M-400A2 it in. the other takes like 20 seconds to start in either A2 as well.

Mike, how many streetlights do you have now? 6 I think?

The OV-25, the M-400, the OV-10, the M-250A, the OVC, the M-250R1, the other "C" M-250R1, the two M-400A2s, the RMA nema head, and sometime next year I'll be getting an OV-15 TuDor from Joe Maurath and maybe I'll see if I can accomodate room for a silver 60s M-250R. So ten right now (11 right now if you count the LED street light, though i don't lol)

Wow! That's a lot already!
The only ones like that I have are an ElectriPak 175W MV yardblaster and that 70s 250w HPS M-400A my godfather has that I will pick up someday.

Does the M-400A have a NEMA tag? it could also be an 80s M-400A too. The M-400A was made from the mid-to-late 60s up until the mid 80s I believe. Then the M-400A2 took over, which looks almost the same. The only external differences are that the PC got moved up, the spring latch became a bail latch, the slipfitter went from a external 2 bolt to an internal 4 bolt, and the later M-400A2s didn't have the ridges in the top housing. internally there are more changes thogh.

the reflector was changed and the lamp became street side instead of house side. That said, the socket bracket had to change. The very first M-400A2 powr/modules had vents but when they got rid of the ridges they got rid ofthe vent holes. The M-400A and M-400A2's powr/modules are interchangeable (but the plugs are different). I'm sure the screw holes are different too. The M-400A2 and M-400R2 use the same top housing so the ballast in a M-400A2 could potentially be top-mounted but it wasn't ever sold that way as far as I know... Inside the slipfitter rocker was replaced with a simpler 4-bolt fitter (though the early M-400A2s and R2s had the 2-bolt rocker fitter at first). The M-400A2 also had the new tool-free spring-held PC receptacle whereas the M-400A had the two-screw PC receptacle.

Most of that is going over my head honestly as I'm not very familiar with /interested in streetlights but IIRC the socket was "house-side"; it was on the side that pointed TOWARD the street; it was part of the whole ballast assembly. My godfather and I opened it up and we were like, "That's a lot going on in there!" then scratched our heads for a bit then closed it back up.
Yes it had a NEMA tag, with the 25. It was faded to silver so I couldn't tell if it was MV. (I was kinda hoping it would be). It might be but otherwise why would there be a circuit board-looking thing? I assume that would be an ignitor. I would check again but it's not mine yet and is in another state (I'm in Alaska, it's in California).

Sounds like a 250w HPS unit to me. The silvery tag suggests that it originally had a foil yellow tag, and of course the circuit board thing is the ignitor.

Yeah my thoughts exactly...the tag likely faded.

yep silvery 25 tag is a 250W HPS M-400A. For clarity, is it about 3ft long? you might want to make sure it's 120V, though if it's got a huge ballast it likely is. the 200+ older HPS fixtures were commonly 240V since simple reactors could be used.

Yeah, luckily my B2255 was a 120v light. It's 120v single tap though.

There were two "transformer" looking things...like a giant preheat choke. (I know, that sounds pretty dumb). I think we may have figured out it was 120v by following wires but I don't remember.

If there's two coils it's probably not a reactor ballast. It's probably a CWA or a HX then which means it might be a 120v ballast.

yeah a reactor has one single coil grouping like a prehat choke. Also the voltage is marked inside the fixture on a white paper tag titled GENERAL (GE) ELECTRIC and underneath that the subtitle is LUMINAIRE. the paper label may have corroded though. it is typically near the ballast on the inside of the top housing. the powr/door should have a little label inside too.