A little backstory. The plant where I work has deemed the 100W medium base HPS bulbs as obsolete and does not stock them. I know they aren't obsolete but some pencil sharpener somewhere has tied his bonus to saving the cost of stocking these lamps. We have hundreds of these sized fixtures scattered all over the plant site, along with every other variation of every different style/size lamp invented. It is suggested I replace the perfectly good fixtures with Metal halide or LED fixtures. Which I do as I am not averse to changing a bad fixture with something more modern, but it angers me to tear out a perfectly good fixture, spend upwards of $700 on a new fixture and labor for a $10 bulb. Since we have an abundance of 70W HPS Medium based bulbs still in stock, what are the risks or pitfalls of using this lesser watt lamp in a higher wattage ballast? Remember, if it ruins the existing fixture It will be replaced with probably an LED fixture. Sunday night is lighting night.....yippee!
70W HPS bulb in a 100W HPS fixture.....
- Thread starter sloinker
- Start date
Are the fixtures 120V? If so just bypass the ballast in the HPS fixture and put cheap LED equivalents in them. Your pencil sharpening bean counter will think you're a genius. Edit: nevermind, forgot HPS light output is nuts compared to LED or incandescent... isn't it? I only suggested this because I did this a LONG time ago, but I honestly can't remember what wattage HPS we replaced with LED, or what wattage the LED bulbs were.
I don't think you're SUPPOSED to use lower wattage bulbs in HPS or MH fixtures but it's somebody else's money, so...
I don't think you're SUPPOSED to use lower wattage bulbs in HPS or MH fixtures but it's somebody else's money, so...
Last edited:
They actually sell a direct replacement LED without bypassing the original ballast but they aren't buying them. Once I crack the fixture open to do the bypassing, I am a quarter way to just replacing it anyways. W.B. can afford it. Just seems wasteful.
I think I've tried that once and it didn't work, the light would flicker. but that could have just been in the particular combination of bulb and ballast, and 230V supply.
yes, I accidentally grabbed a 70W bulb when we were out of 100W
I used to work for an electrical-supplies wholesaler and received a lot of training in the lighting of the time. Every HID type and wattage has its own ballast for a reason. LED lighting has made my old training obsolete, and I'm not sorry. HID fixtures had lots of failure points, including the bulb, the capacitor, and the ballast, and the assembly was very heavy. A "cobrahead" streetlight fixture with bulb, glass, and ballast could weigh nearly 50 lb (~20 kg), and it isn't unusual to see old streetlight arms on power poles bent from corrosion + fixture weight.
Like my training, all HID, including high-pressure sodium, mercury vapor, and metal halide, is very obsolete. If you insist on trying 70 W bulbs with a 100 W ballast, even if they work (they won't, at least not well), you're just postponing the inevitable. Just change to LEDs and don't look back. The heat load in the building will drop dramatically, and you should see some savings in electricity usage too.
In my house I changed to compact fluorescents and, more recently, some LEDs. No way I'm going back to old-style incandescents. You should look at those old HIDs the same way.
Like my training, all HID, including high-pressure sodium, mercury vapor, and metal halide, is very obsolete. If you insist on trying 70 W bulbs with a 100 W ballast, even if they work (they won't, at least not well), you're just postponing the inevitable. Just change to LEDs and don't look back. The heat load in the building will drop dramatically, and you should see some savings in electricity usage too.
In my house I changed to compact fluorescents and, more recently, some LEDs. No way I'm going back to old-style incandescents. You should look at those old HIDs the same way.