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 Livewire78 04-12-2010 04:57 PM

Dusk till Dawn Light (Pole Light)

I have a dusk till dawn light that keeps throwing the breaker, except when I take the photocell out, then it doesn't trip. When I ohm out the light with photocell in it reads complete circuit, however with the photocell out it reads open. Any suggestions?

 andrew79 04-12-2010 05:20 PM

the photocell needs replacing....you should never have zero ohms through a light. There is a dead short in your photocell. If you did an ohm test during the day the photocell should have it as an open circuit and give you and open. At night it would close and you would read the resistance of the light, which should never be zero.

 Livewire78 04-12-2010 05:35 PM

Thanks, I just tested the photocell. It has three prongs and Im assuming that biggest prong is the ground and the other two are L1 and N. I ohmed across L1 and N and it read a circuit. Did I get the prongs right?

 andrew79 04-12-2010 05:40 PM

it's hard to say which prong is which....test out the resistance between each two prongs(3 tests)...it will depend on the shelf state of the cell too. You should read infinity on two of the test and either continuity or infinity on the third depending on wether the cell is in the open or closed state.
what's the model number on the cell?

 Livewire78 04-12-2010 05:57 PM

Quote:
 Originally Posted by andrew79 (Post 427772) it's hard to say which prong is which....test out the resistance between each two prongs(3 tests)...it will depend on the shelf state of the cell too. You should read infinity on two of the test and either continuity or infinity on the third depending on wether the cell is in the open or closed state. what's the model number on the cell?
I looked at it closer and it is labeled, I was correct. From Line to Load there is continuity. There is a resisistance value on L1 to N, and a resistance value from Load to N. About 1900 ohms. The photocell is a RAB model is p-001-120 I think and if that dont work here is another number, e195438. 1800 watt tungsten,,,, 1000va Ballast,,,,,,,, 120vac...

 andrew79 04-12-2010 06:06 PM

either the photcell has gone bad or it was miswired. It's somehow putting out a short between line and neutral or line and ground. My best guess.

 Livewire78 04-12-2010 07:23 PM

So on my photocell, across line and load should I have continuity in the daytime or night time ? Or how does that work?

how do I know if its bad.

 Yoyizit 04-12-2010 07:55 PM

Quote:
 Originally Posted by Livewire78 (Post 427783) RAB model is p-001-120 I think and if that dont work here is another number, e195438. 1800 watt tungsten,,,, 1000va Ballast,,,,,,,, 120vac...
Couldn't find it on their website. You have a link directly to your model?
There can't be too many ways to hook this thing up.

BTW, passing short circuit through it for the short time before the breaker opened probably shortened its life or else clobbered it outright.

If you're using an incand. bulb, what's the wattage?

"A. . .cadmium sulfide (CdS) cell is a resistor whose resistance decreases with increasing incident light intensity."

 Livewire78 04-12-2010 08:03 PM

Quote:
 Originally Posted by Yoyizit (Post 427866) Couldn't find it on their website. You have a link directly to your model? There can't be too many ways to hook this thing up. If you're using an incand. bulb, what's the wattage?
This is a street light/pole light, It was given to me used without the bulb. and havnt bought the bulb yet until I get the light from tripping the breaker. I was told it was probably the photocell but I would like to know how to test it. thanks. oh by the way to answer you question , its not a incandesent light. I believe its a high pressure sodium

 Yoyizit 04-12-2010 08:14 PM

Quote:
 Originally Posted by Livewire78 (Post 427870) I would like to know how to test it.
A schematic is best.
Next best is a closeup photo of the insides and outside.

How many terminals does it have and what are their labels? Just L1, N and Load?

In any case, using a lamp as a load and a current-limited source [120v in series with a 25w incand. lamp] there are some non-destructive tests we can run. You already have a VOM or DVM so this should go quickly.

 Livewire78 04-12-2010 08:29 PM

Quote:
 Originally Posted by Yoyizit (Post 427877) A schematic is best. Next best is a closeup photo of the insides and outside. How many terminals does it have and what are their labels? Just L1, N and Load? In any case, using a lamp as a load and a current-limited source [120v in series with a 25w incand. lamp] there are some non-destructive tests we can run. You already have a VOM or DVM so this should go quickly.
yeah just the three

 brich 04-12-2010 08:30 PM

Quote:
 Originally Posted by andrew79 (Post 427772) it's hard to say which prong is which....test out the resistance between each two prongs(3 tests)...it will depend on the shelf state of the cell too. You should read infinity on two of the test and either continuity or infinity on the third depending on wether the cell is in the open or closed state. what's the model number on the cell?
If it's a standard turn-lock plug the largest plug contact on the photocell should be the ground. In NEMA configurations they always oversize the ground so that it makes first and breaks last when using the device.

 Livewire78 04-12-2010 08:37 PM

Quote:
 Originally Posted by brich (Post 427888) If it's a standard turn-lock plug the largest plug contact on the photocell should be the ground. In NEMA configurations they always oversize the ground so that it makes first and breaks last when using the device.
yes thats what it is. photocells confuse me:eek:

 andrew79 04-12-2010 08:43 PM

Quote:
 Originally Posted by Livewire78 (Post 427896) yes thats what it is. photocells confuse me:eek:
there should be no continuity between the ground and either side of the switch(cell)

 frenchelectrican 04-13-2010 01:43 AM

you can take a conuity reading on the photocell and between the netural { wide blade } to either one it should not read anything at all or read very high ohms numbers depending on which way you read it.

However some photocell have default feature if failed some are designed to stay off during failure mode and some are designed to fail and they stay on.

The one I get all the time when the photocell fail they stay on { that is my peferince } it make trouble shooting little easier and also I keep few shorting caps on hand in case have to do quick testing with any luminaire with twistlock photocell.

The real cheap photocell if they fail they will stay off.

However some photocell do have lighting arrestor or surge protection in there one of the two if that go bad it will act like short circuit.

Now next step if you can get a shorting cap or get new photocell and if that trip the breaker sound like the ballast is pretty much toasted.

For the plain jane common dusk to dawn luminaire it cheaper to just buy the whole new thing than try to order a ballast that will fit in the NEMA dusk to dawn luminaire unless you have other oddball voltage that it on that circuit { I know I did see few NEMA DTD's { DTD = dusk to dawn } did have wired for 240 volts { not very often but it will show up once a while}

As far for HPS there is very specific wattage you have to use in the DTD luminaire either they will stamp the wattage or ANSI ballast number one of the two or both and with cheap HPS DTD do not have any capiaitor at all it is a reactor ballast nothing more at all. the only item you will find in there is starting ingitor there are few diffrent shape and sizes however one serious warning when you test this do not run your voltmeter on the starting circuit at all due very high voltage will show up during start up { it can go up much as 3500+ volts } this not only affect the HPS but with pulse start Metal Halide as well.

If you have more question just holler one of us will help ya.

{ this part I do it pretty often }

Merci,Marc

Yoyizit:

For the HID ballast like cheap DTD typically will be wired in Reactor { simauir to choke coil on flourscent ballast } plus ingitor if HPS or PSMH otherwise some will have HX { autotransfomer reactor } as well.

I will throw a link little later so you will get more clear idea what it look like.

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