Lower wattage HPS bulbs?

[BatteryCharger]

I'm installing a 250 watt HPS flood light fixture on the outside of my shop, using this particular fixture because it was free, brand new, and industrial grade. I think 250 watts might be a little too bright though. Is it possible to use lower wattage HPS bulbs in a 250 watt fixture? (magnetic ballast) Something like 150 would be a lot better...

 

[shortstack]

Did it come with a manual? I know on my 70w HPS light I got froms lowes, in the manual/instructions it says to use a 70w or less for a bulb. You should be fine with a smaller wattage bulb Check the manual? Maybe someone else can also verify this.

 

[Random Guy]

No. Discharge lamps and their ballasts are a matched system. A 150 watt lamp on a 250W ballast would be severely overdriven, and may explode. If you want less light, you will have to use a different fixture. Conversely, it is also bad to use a lamp on a ballast meant to drive a smaller lamp (say, a 400 watt lamp on a 250 watt ballast). The lamp will never warm up properly, and will draw too much current. This will cause the ballast to fail.

 

[BatteryCharger]

Hmmm, I might get a new 150w metal halide ballast instead - not too excited about the HPS light color anyway. I don't know though, I'll plug it in and see what it looks like...

 

[Random Guy]

Keep in mind that metal halide is less efficient than HPS, so a 150W MH lamp will be dimmer than a 150W HPS lamp. However, the light will be much whiter (About 4000K instead of 2000K, and no, that is not a typo) and render color much better (a CRI of about 60-70 instead of about 20, also not a typo). Look at the specs for different wattage MH and HPS lamps to decide on a type and wattage you want. Make sure you look at mean lumens, not initial lumens, as HID light sources can get quite a bit dimmer over their lives. Also, buy good quality lamps. With HID lamps, you pretty much get what you pay for. Cheap lamps will not last as long, and you will find yourself getting out the ladder to change the lamp more often than you'd like.

 

[JohnR66]

I agree with Random Guy on this. I understand that there are phosphor coated MH bulbs available that have even better CRI. Since the color of MH has much more green in the spectra, it may appear brighter than HPS even though the HPS lamp puts out more lumens.

 

[BatteryCharger]

Yeah, that's why I wanted to use the MH bulb, because the rest of the place is already lit up with them. I think the HPS would stand out too much and look funny. They do make 250w MH "conversion" bulbs that should work in this fixture, though I'm not sure if that will be too bright or not. This is an industrial building but there is a guy living on the second story in the building across my parking lot...I don't think he wants me blasting him with lights all night.:ironic:

Then again I may just put the whole fixture as is on ebay, it's really just more than I need. I'm sure it was expensive, it's definately nice, heavy duty commercial quality. Somebody will probably want to grow pot with it. LOL

 

[BatteryCharger]

Another thought - could I use a 250w MH lamp with the 250w HPS ballast if I remove the ignitor? How does an HPS ballast differ from a MH ballast?