[Smokewagun]

So, several nights each week, I notice the high pressure sodium light fixture I have hanging on my barn goes out completely, then it comes back on (slowly -like usual warm-up). No, it is not from lightning, this is on a clear night. Anyway, I see last night it is flickering ever so slightly. I had "going out" issues several years ago, and replaced the bulb. I can't say it resolved the problem completely, but after I told my Dad about replacing the bulb, he said his same fixture has the origial bulb after fifteen years. Is this issue the bulb? The ballast? Or the photocell? I have had minor on/off issues forever, which I thought (as stupid as it sounds) was from a moth flying over the photcell and reflecting light into the cell, which thought it was light out, thus shutting off. Anybody been here before? Maybe I should just replace the entire fixture.

 

[RightWingNutJob]

I've got a couple of Hubell HPS fixtures that're >15 years old. So far whenever I get the on-off-on-off problem, it's always been resolved by changing the bulb.

 

[cbuttre835]

A 'cycling' sodium light is caused by the bulb being bad.

The arc tube gets too hot and cannot sustain the arc.

once it cools, it'll restrike and run for a couple minutes, till it gets too hot again.

They're rated for 24,000 hours. anything over that (Dad's fixture) is icing on the cake. They may last 15 years, they may only last 2.

Kinda 'luck of the draw' on what kind of bulbs you get.

 

[Smokewagun]

So, is there anything that couldbe causing these bulbs to fail, or am I just getting 'bad ones' compared to Dad? I hate to keep replacing bulbs every few years if there is something causing the failures. Thanks,

Smoke

 

[bilbo]

I believe it is the ballast.
The windings (transformer) short/open, allowing the coils to cool..then the short clears...cycle startsts again.

 

[cbuttre835]

[ QUOTE ]
So, is there anything that couldbe causing these bulbs to fail, or am I just getting 'bad ones' compared to Dad? I hate to keep replacing bulbs every few years if there is something causing the failures. Thanks,

Smoke

[/ QUOTE ]

Change vendor of bulbs.

Spend the extra money and buy one with double arc tubes, too. Will save you trips up the pole. (or ladder)

I disagree with the the post below yours. Bad ballast will manifest itself rapidly. A cycling light like you describe (does it do it constantly, all night?) is no more than a bad bulb. A dual arc tube lamp will instantly strike the other tube when one fails, saving wear and tear on your starter as well.

http://www.americanelectriclighting.com/Library/Literature/PDFs/HPS%20Servicing%20Guide.pdf is a good reference. Start around page 19.

 

[MADVAN]

Lamps are also vert or horz burn.

Bill

 

[Birken Vogt]

Vertical or horizontal applies only to mercury/metal halide as I recall, not HPS but I could be wrong. But I thought that not having to worry about that was one of the advantages to retrofitting HPS bulbs into merc/MH fixtures.

Birken

 

[checkthisout]

Sounds like the bulb is worn out.

Mundane I know but also make sure the photocell isn't receiving reflected light and causing the lamp to cycle.

 

[Smokewagun]

Thanks for the responses everybody. I'll check the photocell, and replace the bulb. After that, we'll see. I'll let you know what happens. Thanks again.

Smoke

 

[2106]

There was a post here about this same problem about a year or so ago. I had the same thing happening in the past. One time I replaced the photocell for about $10 and that fixed it for a long time (years). A few years later it did the same thing again and I replaced the photocell and problem existed. Changed the bulb and all was well.

Bottom line.....change the photocell first ($) and it not fixed try the bulb next ($$$).

 

[FloridaEd]

It's called end-of-life cycling. Normally it's the lamp, but if it goes on long enough, it will get the starter and sometimes the ballast. HPS lamps have a sodium mixture in the arc tube of the lamp. Each time it goes on, a small bit of the mixture will deposit on the inside of the arc tube. Over time, this build-up (blackish) will remove enough of the sodium mixture that the arc will collapse: thus the lamp lights up normally, then it goes "out like a light". As soon as the arc tube cools a bit and the sodium mixture coalesces from gas, it will re-strike as on a normal start. Over and over...

HPS lamps are generally rated abour 20,000 hours burn time, but their life expectancy goes way down if the burn sequence is less than about 12 hours. (This is the "big lie" about CFL - compact flourescent lamps - they don't last nearly as long as claimed because they tend to be turned off and on much more than the testing used to get the life expectancy.)

First, if you have a switch, turn off the fixture. Then replace the lamp. You may find in the future that the lamp just won't go on.. that indicates the starter (most likely) or the ballast is bad. Anymore, the complete fixture with lamp is so cheap, you're often better off to just buy a complete system.

The best choice for these lamps are the 150W or 400W units. These wattage systems are standard for the D.O.T.'s and utilities around the country and are made by the millions each year... thus cheaper than any other size lamp. I still think the best deal is from the local utility company... just pay $4-5 a month.. that's where I get my 150W HPS area light.

Florida Ed

 

[Birken Vogt]

[ QUOTE ]
I still think the best deal is from the local utility company... just pay $4-5 a month.. that's where I get my 150W HPS area light.

[/ QUOTE ]

I was going to start a thread about that because my curiosity had gotten to me on that subject. Since they are not metered who pays the bill. Now I think I know. It is amazing to see where some of them are located illuminating fields of weeds and blackberry bushes where no one has set foot for many years...I guess they just keep paying their bill....

Birken