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Dusk till Dawn Light (Pole Light)

18K views 15 replies 5 participants last post by  Yoyizit 
#1 ·
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?
 
#2 · (Edited)
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.
 
#4 ·
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?
 
#5 ·
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...
 
#6 ·
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.
 
#15 · (Edited)
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.
 
#16 ·
With just three terminals, I'd think the contacts go between line and load terminals, and the CdS cell is in series with a ~2w resistor or resistance wire which heats a bimetallic switch. With line voltage and light applied the current through the resistor opens the bimetallic switch.

No power and/or no light closes the switch after a time lag.

The resistance from line to N depends on the resistor value and the CdS cell, and is indeterminate.

The contact integrity can be checked: at rated current no more than a 30 mV drop across the closed contacts is good, more than 100 mV is bad.
 
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