Hi there.

I'm on to my next HID lighting project and I plan on building a 50w Mercury Vapor "mini bucket" light, Like the white and black 100w MV Regent used to sell back in the day.

I know a 50w MV ballast is going to be tough to find locally but what are my other options as far as ballast choices?  I have seen other members use non MV ballasts on Mercury lamps before.

Whats the lowest wattage PSMH ballast you can get? I'm pretty sure I want to stay away from the new electronic type if I'm correct?

Thanks!

I saw that you can use a f40 autotransformer ballast on a 40/50w merc. I don't think it'd fit in a standard NEMA head due to length but you can house it in a waterproof metal enclosure.

A 50w MH ballast would work, just without using the ignitor. The mercury lamp will be overdriven a bit, but wont affect life to badly. A 39w MH ballast would be ideal, but today your only option for that is electronic, which I wouldn't recommend.

I saw that you can use a f40 autotransformer ballast on a 40/50w merc. I don't think it'd fit in a standard NEMA head due to length but you can house it in a waterproof metal enclosure.

I'm going to try this and I see what you mean, the F40 ballast is not going to fit very well in a Nema head lol.

I dont think the F40 ballast will run the 50w MV lamp to full brightness tho. Only one way to find out!

A 50w MH ballast would work, just without using the ignitor. The mercury lamp will be overdriven a bit, but wont affect life to badly. A 39w MH ballast would be ideal, but today your only option for that is electronic, which I wouldn't recommend.

Himm sounds like an option. I if I was to install a capacitor in series before the lamp, would this be a form of Bi level dimming? Can you install a cap in series before the ballast or before the lamp to reduce lamp output?

Carefull there, wrong value of the capacitor may increase the output. Posibly even to the point of immediate lamp damage

The capacitor would have to be on the lamp side (so on the secondary), to not reduce the OCV.
But as Ash wrote, if it's some wrong value (the worst would be 9uF), the current would be practically not limited, so you will most likely fry all things there: The lamp, ballast, as well  as the capacitor.

For real dimming the capacitor would have to be below about 4.5uF (so about 3uF would lead to about half of the lamp power), but it would have to be rated for at least 450VAC/60Hz.
Better would be to use some series choke, e.g. some 55V HPS ballast (only the inductor, leave the "Neutral" not connected; e.g. the 35W HPS ballast inductor would work fine), there you have no risk of the current becoming accidentally higher instead of lower.

I kinda understand whats going on here but Im pretty lost lol.

I would like a way to be able to reduce the lamp lumens output of my 100w MV and 175w MV Nema fixtures.

Here is a magnetic 39w MH ballast.

Here is a magnetic 39w MH ballast.

Hey there and thanks.

I wonder if I could locate this here in my town. Are these rare?

You could try an electrical supply store. They don't seem to be very common, though, as most are electronic.

I will call around and ask. I did some digging and found a Sylvania PN#47203 is a 35w MH ballast kit. Most electrical supply places in my area are very unhelpful when it comes to this sorta rare hard to find stuff. I wish a 50w MV ballast wasn't so hard to find! I bet at one time they were easy to buy from your electrical supply store.

That Sola is going to be your only option for a magnetic that's closest to the 50w MV spec. Im actually surprised that's even available, all other manufacturers, GE, Advance/Philips, Sylvania have done away with magnetic 39w MH years ago. I personally would go with a 50w MH ballast, a bit more light out of the mercury lamp, as well as the option for you to switch to a MH lamp and instantly double the light if you ever needed more light. (a 39w medium base MH lamp is nearly impossible to find unless you want a reflector lamp)

Back in 2005 I worked with a contractor that replaced a few bad ballasts in 50w MV recessed cans, those shiny new Advance 50w mercury ballasts cost just $15.00 each from Graybar, kinda makes you sick doesn't it...  I hate bulb/ballast bans

I got my VS 50W MV ballast in 2013 if I still remember. The ballast costs me HKD$98 (about USD$13, or £8)
Pretty good ballast these, but runs a bit too hot!