# Dusk to dawn light



## Signal Guy

make sure you have power to the unit. 
usually, the photocell will fail in the always on position. 
the easiest way to check the photocell is to cover it with tape. I usually just stick a glove over the large ones. it may take a few minutes for the photocell to turn on.
There should be 3 wires on the photocell. most likely, black, red, and white. The black should be always hot. The red should be hot when the photocell is on. The white should be connected to your neutral.
this is all assuming a 120V fixture/photocell.


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## frenchelectrican

Signal guy have right idea but let me add this part is that when you replace the bulb make sure they are matched up to the old one.

The most common way to kill the photocell is the power surge that useally toast them. ( even use wrong voltage will do it as well. ) 

Is your Dusk to Dawn luminarie is Mercury Vapour ( white/bleuish colour ) or High Pressure Soduim ( Orange colour ) or CFL ( Whiteish colour ) or Metal Halide ( useally whiteish colour with either a pink or bleu colour will show up <not much but just engough to noticed>)

Second thing do you have a wall switch that control this luminaire or not ?

If so you may want to make sure you have good power source before you get up there and do the testing.

Merci,
Marc


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## Signal Guy

frenchelectrican said:


> Signal guy have right idea but let me add this part is that when you replace the bulb make sure they are matched up to the old one.
> 
> The most common way to kill the photocell is the power surge that useally toast them. ( even use wrong voltage will do it as well. )
> 
> Is your Dusk to Dawn luminarie is Mercury Vapour ( white/bleuish colour ) or High Pressure Soduim ( Orange colour ) or CFL ( Whiteish colour ) or Metal Halide ( useally whiteish colour with either a pink or bleu colour will show up <not much but just engough to noticed>)


Good point, can't believe I missed that.


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## frenchelectrican

Signal Guy.,

For the photocells for the failure mode I know few will be stuck on mode when they go bad and few will not come on at all all it depending on which photocell you order it.

Most photocells I order them useally have luminaire be on in fail mode in most place but few are reversed ( common with large street luminaries )

Merci,
Marc


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## Signal Guy

frenchelectrican said:


> For the photocells for the failure mode I know few will be stuck on mode when they go bad and few will not come on at all all it depending on which photocell you order it.


Thanks, I wasn't aware of that. my experience is mostly with on-street lighting, so thats all I see. 
A friend of mine always says that if I'm not careful, I'll learn something new every day.


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## daltis

Thank you for the helpful information. Yes, it does have a wall switch and I do have voltage going to it. Is it possible to bypass the photo cell to test the lamp?


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## frenchelectrican

daltis said:


> Thank you for the helpful information. Yes, it does have a wall switch and I do have voltage going to it. Is it possible to bypass the photo cell to test the lamp?


It possible depending on which type of photocell you have there.

For the button type as I will post the photo and the twistlock verison those two are most common style we used either North Americia side and European side.

Here the button photocell look like .,










Now here the twistlockers look like.,










Just keep in your mind the twistlock will show few differnt style and shape but functionwise they are the same ( just pay attetion to the voltage rating for all photocell types.

Merci,
Marc


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## daltis

The type on the light I have is the twistlock. Thank you so much for the helpful information.


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## frenchelectrican

OK now we are getting somewhere.,

As one of the poster ( signal guy ) did suggest to use the dark gloves to cover the photocell that will take couple second up to couple minutes before they will turn the luminaire on.

For myself I keep a shorting cap with me some case it will be more than basic troubleshooting then I use the shorting cap. ( not very many place will stock the shorting cap for it but it justifed the cost if you do troubleshooting or the Luminarie do come with photocell but want to bypass it due it controled by timer so it do happend )

When you untwist it will turn a little probly about a eighth turn not very much turn but you will feel it.

But when you put it back on or replace you will have to make a note which way the Nord ( North ) is facing due the twistlocker will have one blade is larger than other two.

Hope that will help ya.

Merci,
Marc


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## daltis

If I remove the photocell and cover it with tape should I have continuity between the 2 "hot" blades?


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## frenchelectrican

daltis said:


> If I remove the photocell and cover it with tape should I have continuity between the 2 "hot" blades?


Not really you need the power to get the sensor to read it right.

Unless it allready got a magic smoke builded up ( you can able tell if the whole thing is black inside or smell burnted.

It will be wise idea to pick a new photocell they are not that expensive IIRC about 10 Euros or so for a good one the cheaper one will run about 8 Euros keep in your mind it depending on where you get it from.

Merci,
Marc


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## daltis

I did notice that the photocell was black inside. Your information has been very helpful. Thank you.


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## Hardway

Don't forget to check the date on the new photo cell.


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## daltis

I replaced the photocell. I also found a wire inside of the light itself that was broken in two. I repaired the broken wire. I wrapped black tape around the photocell and checked the voltage at the light socket. I had 122 volts. When I installed the bulb it still would not come on. I replaced the bulb to be sure. The light is still not working. I am not sure what else to check since I have the proper voltage at the socket. Do you have any suggestions?


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## Hardway

What is the voltage of the bulb?


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## daltis

It is 120v.


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## frenchelectrican

daltis said:


> It is 120v.


Ok you say 120 volts but what type of bulb are we talking about as I posted above MV or MH or HPS or CFL ??

That will make the differnce on how to make the troubleshooting here.

The MV ( common 175 watters ) dusk to dawn luminaire the open circuit is typically about 250 volts it will be mesured at lamp socket or ballast secondary leads.

So if you did read the voltage and come out 120 volts then the ballast is shot.

For other type or other wattage size let us know we will tell you the correct voltage rating on lamp socket.

Merci,
Marc


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## daltis

It is MV and 175 watts. Thanks.


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## Hardway

frenchelectrican said:


> Ok you say 120 volts but what type of bulb are we talking about as I posted above MV or MH or HPS or CFL ??
> 
> That will make the differnce on how to make the troubleshooting here.
> 
> The MV ( common 175 watters ) dusk to dawn luminaire the open circuit is typically about 250 volts it will be mesured at lamp socket or ballast secondary leads.
> 
> So if you did read the voltage and come out 120 volts then the ballast is shot.
> 
> For other type or other wattage size let us know we will tell you the correct voltage rating on lamp socket.
> 
> Merci,
> Marc


Sent from phone. Thanks for taking the ball and running with it.


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## frenchelectrican

Hardway said:


> Sent from phone. Thanks for taking the ball and running with it.


Pas de Problme ( Not a problem ) 


Merci,
Marc


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## hvac/r- pro1

I am having the same exact problem ,getting 122v and bulb will not fire up. I think it may be a bad transformer or loose ground.


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## hvac/r- pro1

*dont know*

Daltis,i am having the same exact same problem122v, new bulb and, will not fire up.maby transformer,or loose ground wire.:whistling2:


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