High Pressure Sodium Lighting

Old 01-16-10, 12:10 PM
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High Pressure Sodium Lighting

I have a Utilitech Model UT-5666-AL High pressure sodium security lighting . The pole light worked great for the first year. Now the light goes out and restarts several times per night. My electric bill has skyrocketed the last two months. I assume it has something to do with the light restarting. The owners manual doesn't have any troubleshooting section in it. Any ideas what might be causing this?
Old 01-16-10, 12:34 PM
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Most cases when the lamp goes out and then relights it is the lamp that is failing. Odd that lamp would fail in such a short time because HPS lamps should last 20,000 hrs. The easiest way to test the theory is to just replace the lamp.

If you change lamp and it still does the same thing then you need a new ballasts. Knowing it is a Utilitech light it might be cheaper to replace the fixture than to replace the ballast.

I can't for sure say this is why your electric bill has skyrocketed but it seams unlikely.
Old 01-17-10, 12:27 PM
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failing lamp

I have to concur with Tolyn -

from wikipedia

At the end of life, high-pressure sodium lamps exhibit a phenomenon known as cycling, which is caused by a loss of sodium in the arc. Sodium is a highly reactive element, and is easily lost by reacting with other elements, and migration through the arc tube walls. As a result, these lamps can be started at a relatively low voltage but as they heat up during operation, the internal gas pressure within the arc tube rises and more and more voltage is required to maintain the arc discharge. As a lamp gets older, the maintaining voltage for the arc eventually rises to exceed the maximum voltage output by the electrical ballast. As the lamp heats to this point, the arc fails and the lamp goes out. Eventually, with the arc extinguished, the lamp cools down again, the gas pressure in the arc tube is reduced, and the ballast can once again cause the arc to strike. The effect of this is that the lamp glows for a while and then goes out, repeatedly.

though if you read that it might well be the lamp pole fixture is try to meet the voltage required by the failing lamp, and so the rise in you bill, but how much of a rise in the bill are we talking?
Old 01-17-10, 02:10 PM
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this is from a field experience education and not "by the book" but I have had a fixture that acted similarly and upon replacing the lamp (and I had an identical fixture across the room to compare to) I realized the light color was more yellow than the other fixture with an equally new lamp. Upon replacing the guts (habit, all or nothing) the two fixtures were equal in color and intensity. When just replacing the lamp, it did remedy the cycling but there was that color difference.

I suspect the ballast was partially shorted and not producing enough voltage or current to run the lamp properly and as a result, shortened the life of the lamp as well as not producing proper light output.

the bill would go up simply due to the cycling regardless of the reason as there is a starting current that exceeds run current in HID fixtures.

So, it could be the lamp or the internals causing the cycling (resultantly anyway) and the higher electric bills.
Old 01-21-10, 02:52 PM
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Bulb didn't fix it

I tried a new bulb, but it didn't work. You stated that it is usually cheaper to replace the light than the ballist. With your experience, what is a good brand and type to buy?
Old 01-21-10, 06:04 PM
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There are few good one that can be used on post useage for dusk to dawn operation.

Normally I use three or four diffrent brands depending on wattage and type.

If you don't like the orange colour you can get it in Metal Halide verison or Super compact flourscent both have decent white light.

Keep in your mind you will not get Mercury Vapour anymore at all. { pretty much history now }

The super compact flourscent can be used in very cool weather { above 10°F } but I don't really recall which one can work more colder but for Metal Halide it will not affect it at all.

The bulb lifes between the MH and SCFL are about the same { about 12,000 hours or so depending on wattage }


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