Night Lights, Mercury Vapor VS HPS

[BobinIL]

I just finished building a new shed and was going to put a night light up over the main door. While I was in the local farm store I noticed two types. The old standard Mercury Vapor and then there was the High Pressure Sodium that I know nothing about. What are the pros and cons? I plan on getting one in the 175 watt range. I remeber when I used to farm some 15 years ago, we always had the old mercury vapor lights around the barn lot. They were expensive to run, we calculated that one 300 watt Mercury light cost about $30.00 a month to run We were running 3 of them at a farm we rented and the electric bill was around $90.00 a month. We quickly turned two of them off.

 

[Doc_Bob]

They were expensive to run, we calculated that one 300 watt Mercury light cost about $30.00 a month to run We were running 3 of them at a farm we rented and the electric bill was around $90.00 a month. We quickly turned two of them off.

I stopped running all outside lights continuously. Now I just have motion detectors. Light on, light off. My barn is light free. I don't need to have it lit at 2 am. No one is looking .
Bob

 

[Onthesauk]

Most of my outside lights are on motion detectors but have a pair of floods on the barn. Bought a couple of 150 watt florescent floods that are more then adaquate and very cheap to operate.

 

[gizmo]

You may also want to consider metal halide lamps. They are the high intensity discharge (HID) lamps with a nearly white output and have the most lumens per watt. They cost a bit more, but you use fewer lamps for the same output.

 

[kmdigital]

You may also want to consider metal halide lamps. They are the high intensity discharge (HID) lamps with a nearly white output and have the most lumens per watt.

Actually, HPS gives considerably more most lumens per watt, especially as the bulb ages. This is why all city street lights are HPS. For example, a 150 watt MH light produces 13,000 initial lumens and only 8,700 mean lumens while a 150 watt HPS light produces 16,000 initial lumens and 14,400 mean lumens while a 175 watt mercury vapor produces only 7,850 initial lumens and 7,140 mean lumens.

For outside security lighting, HPS is the best solution, but for indoor lighting, use MH or flourescent. HPS light is very yellow in color so it isn't good for accurate color rendering or high detail inside work. However, it is the most efficient and a 70 watt HPS security light at 6,300 lumens will produce all most as many lumens as a 175 watt mercury vapor light but cost much less to operate.

And for even greater efficiency, you can get HPS lights down to 35 watts that still produces a tremendous amount of light for the watts they use. In fact, the lumens from a 35 watt HPS light is on par with the output from a 150 watt incandescent light, so this gives you an idea of the amount of light one produces.

For a table of these figures, excluding the incandescent lights, go to Information Sheet 4 (September 1996)

 

[EddieWalker]

Kmdigital said it better than I can.

I have some 150 watt HPS lights on my driveway that don't draw very much power at all. If memory serves me right, they use the equal amount of electricity as a 60 watt light bulb. The yellow color is barely noticable to me, and so far, nobody has mentioned it.

On the back of my shop I put a smaller HPS light above my workshop door. It's on all night long as is my porch light. They have sensors and turn on and go off on there own. It's nice to have them on no matter what time of the night I might go outside, or if we go out. With the days getting darker earlier, it's VERY nice to have the lights on when my wife and kids come home.

Eddie

 

[Doc_Bob]

Most of my outside lights are on motion detectors but have a pair of floods on the barn. Bought a couple of 150 watt florescent floods that are more then adaquate and very cheap to operate.

Any flourescents that will work well in Wisconsin during the cold weather?
Bob

 

[PineRidge]

Any flourescents that will work well in Wisconsin during the cold weather?
Bob

Bob I used to have a small fluorescent commercial quality lamp at the entrance to our business. It flickered in the winter which was unacceptable.

We use fluorescent and incandescent lamps in our pole barn. In colder months we 1st fire the incandescents until we fire up the heater then switch on the fluorescents, this system works for us.

 

[schmism]

I have metal Hylide and love them. Much better than the old MV and much better color than the HPS.

the HPS is usually used by street depts because the wavelenght of light output doesnt scatter as much in fog and rain haze allowing them to effectlivly light the streets and not the mosture when its foggy/hazy out.

 

[patrick_g]

HPS offers good economy without cold weather starting difficulty. There are high output fluorescent lamps and ballasts that will start reliably to some pretty low temps but not in CFL.

The color rendering index of HPS is good enough for many uses and way better than LPS (Low Pressure Sodium) When I designed the lighting for the Enlisted Dining Facility at SUBASE San Diego I got HPS pendants approved for general lighting in the face of skepticism on the part of the Base Civil enegineer and the architect who was the ROIC (Resident Officer in charge of Construction) I took them to a location where they could see the spectrum of the lamps displayed. The HPS did not make the food look funny.

If you have stringent color rendering index issues then the metal halides or other high index lighting should be used even though they are more expensive to operate.

Light the Night photocell operated general area lighting is more of a service to thieves than protection from them unless there are security or other personel awake and watching the lit area ALL THE TIME. The motion detector lights are far better for unattended areas as the lights tend to attract attention (unwanted attention if you are a bad guy) but are not lighting the area so every bad guy passing by knows what there is to take.

In typical circumstances motion detector lights are on for such a low percentage of the time that it does not pay to install fluorescent floods. In this low duty cycle application brighter is usually better rather than trying to economize and makes very little impact on the monthly bill. If fluorescents aren't going to be on at least an average of say 3 hours (certainly 2 or more) then there is no economic reason to go fluorescent.

Light the night is not a universal good thing and needs analysis. It is frequently better to be out of sight and out of mind except for nice bright motion detector lights.

Pat