Hello, I recieved three retired mercury vapor fixtures that were on a pole. Does anyone know what year this may be from or estimate. Also, I wanted to know if there was a way to reduce the amount of power these use my using a dimmer of some sort. Can I reduce the power with the same 175w bulb?

I wanted to do this to reduce ballast wear because new ballasts are getting harder to find. I plan to keep them on 24/7 but wanted to reduce power costs.

Thank you

I’m not sure what year they are from, but it could be as late as the 1980s or 1990s. The curvature of the top area suggests earlier, more around the 60s or 70s. No, there is no way to reduce the power going to the fixture using a dimmer or any other method of power reduction. It’s meant to only run at full power; trying to limit it would probably cause more damage to the ballast, especially if you use a dimmer.

Isnt the ballast only used during start up?

No, the ballast regulates the current going to the bulb the whole time it is on. The ballast is used for the whole time the bulb is on.

I see. Will a 175w mercury bulb cost the same in electricity as say a 175w incandescent bulb? Or is the 175 rated watts for the mercury bulb a equivalency number kinda like how LEDs are.

A 175W mercury vapor bulb takes 175W. It is not an incandescent equivalent rating.

One more question:

What are some tips and tricks for lengthening the life of these ballasts? Hopefully, these ballasts can last a good 40 years.

Make sure the ballast doesn’t overheat and run it only on the voltage and frequency it was designed for and only use the tybe of bulb it was made for. That’s all I really got.

Nice, these look a bit like American Electric Series 11 NEMA heads. The utility grade ones with the full terminal block. Anyway there some ways to reduce power but they all involve using some alternative non MV lamp.

150w Sylvania Unalux bulbs are made to run on this type of 175w MV ballast and are a drop in replacement but their HPS so they look yellow instead of the bluish green of MV.

I suppose you could also use screw in LED bulbs, some can run directly on the ballast while some require you to bypass the ballast.

To lengthen ballast life, you could try revarnishing the ballasts with some Class H 180C rated transformer varnish or just remove them and remote mount them in a suitable enclosure. That will make them run cooler since it's away from the heat of the lamp which should mean they'll last longer. MV ballasts can be remote mounted from the bulb a fair distance unlike HPS.

HID fixtures are pretty much made for that wattage lamp and if you want to use a lower wattage you'll typically have to replace the ballast to one that run a lower wattage.

175w MV lamps are rated for around 7200 lumens but the light output drops so the incandescent equivalent would be around 300-400w incandescent. 

Where can I apply this varnish? Also do these MV ballasts even fail? Im unsure on how often these mercury ballasts last and if turning them on and off even reduces life?

I made this post for another reply but it might be a help here too. These NEMA lights use a what's called a HX-NPF ballast, which is a fairly simple type of ballast as they don't use capacitors. This also means they will probably be able to last up to 50-60 years doing dusk to dawn service as long the ballast doesn't overheat.

"Any class H or 180C rated transformer varnish should work for this. I usually use MG Chemicals products as my local electronics store stocks them. No. 4228 red varnish works but it bright red in colour so if you don't like that look (works well for early Westinghouse ballasts with were red varnished) you can try something else. I think No. 4226 might work pretty well too since it's clear.

I recently re varnished a ballast using the No. 4228 red varnish and here's how it looks after.

Here's how I usually revarnish my ballasts:
1) remove ballast from luminaire.
2) sand off all loose rust and varnish from the core, be very careful not to damage the coils when doing so.
3) clean off the debris with compressed air, followed by some isopropyl alcohol.
4) run the ballast for about an hour to get the core to operating temperature.
5) disconnect power, then apply varnish by brush directly to the coil and coil. Optionally run ballast periodically to work varnish into coils.
6) let sit for around 30mins at room temperature.
7) run for 1-2 hours to allow the ballast to reach operating temperature which will help it cure faster.
8 ) if you're not in a rush you can leave it overnight before reinstalling.

Bare in mind the varnish does smell quite pungent so make sure to apply in a well ventilated area or wear respiratory protection."

You can reduce power costs on these fixtures by using 150w Sylvania Unalux high pressure sodium retrofit bulbs in these fixtures.

Here is a case of 10 if you really want to minimize power usage on these fixtures:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=ulx150&_sacat=0&LH_TitleDesc=0&_odkw=relco+ignitor&_osacat=0

 Thing with these nema buckets there is not really a way to dim them
 As those mercury ballast runs of very tight voltage tolerences
  Otherwise lamp Wont be reliable staying lit.  And changing the mercury lamp to lower wattage ones. Will add stress to the ballast
A

Put inside them 100w ballasts, sell the 175w ones. Try to keep them MV but any lamp type species can be done, such as HPS, Metal-halide, CFL, ceramic-metal-halide. You're only limited by your imagination.

Hello, I recieved three retired mercury vapor fixtures that were on a pole. Does anyone know what year this may be from or estimate. Also, I wanted to know if there was a way to reduce the amount of power these use my using a dimmer of some sort. Can I reduce the power with the same 175w bulb?

I wanted to do this to reduce ballast wear because new ballasts are getting harder to find. I plan to keep them on 24/7 but wanted to reduce power costs.

Thank you

to make sure this ballast lives a long life, replace the light bulbs every year.  if you are running the fixtures 24/7, then turn off the light fixture for at least an hour every month.