phot cell on a switched light????

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  #1  
Old 02-24-07, 01:01 PM
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phot cell on a switched light????

I have an exterior light on a switch and would like to know if I can put a photo cell on the power side of the switch?

I would like to light to only be operated when dark.
To many times the light is left on at night only to be on all day!!!
I don't want the light all the time or on a motion senser. I just want to cut down on it being left on all day.
Thanks
rickc
 
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Old 02-24-07, 02:14 PM
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Of course you can.
 
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Old 02-24-07, 06:06 PM
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Wink

Put the PC downstream of the switch. Connect HOT (from switch) to the PC black wire, Connect WHITE neutrals (from circuit, lamp, and PC) together, and connect RED (from PC) to BLACK wire of lamp.
Piece of cake:-)
 
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Old 02-24-07, 07:29 PM
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I did that setup on my flag pole spot light. When the weather is nasty and I take the flag down, I switch it off. Otherwise, the PC lights the flag pole while dark.
 
  #5  
Old 02-25-07, 05:44 PM
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Originally Posted by Andrew View Post
Put the PC downstream of the switch. Connect HOT (from switch) to the PC black wire, Connect WHITE neutrals (from circuit, lamp, and PC) together, and connect RED (from PC) to BLACK wire of lamp.
Piece of cake:-)
Pc down stream of switch????
I would of thought up stream?
The PC I have says there is a delay of 5 to 15 minutes wouldn't I want that on the power side of the switch? Basiclly the photo cell will always have power and continue the power to the switch only when dark and then on to the light when closed.

black power line to black pc wire,
Red pc wire to switch,
all white together.

rickc
 
  #6  
Old 02-25-07, 09:24 PM
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Basically, you want to visualize the following: First is the circuit breaker, then the switch, followed by the photo cell and finally the light it self. The circuit breaker is the upstream end - where the power originates and the light is downstream - at the end of the run.
 
  #7  
Old 02-26-07, 07:04 AM
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Rick, your logic is fine. Although it is usually put downstream of the switch, you can put it upstream if you want. As you say, if you put it downstream, and somebody turns on the switch in the daytime, the light will be on for a few minutes before the photo cell figures out to turn it off. I actually kind of like that, because it allows me to see if the bulb is burnt out in the daytime. But I can understand if you want to avoid that because you can't help wondering if it's really going to go off and you stand around watching it until it does.

It's like car headlights and interior lights that go out by themselves after a few minutes--sometimes you just don't trust them and find yourself waiting by your car until they go out.

Ever wondered if that light inside your refrigerator really goes out when you close the door?
 
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Old 02-26-07, 09:04 AM
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You may also want to consider an electronic timer. They have timers that will replace the switch, and can be programmed to go on at sunset and off at sunrise (or any other time of day). They automatically account for changing sunrise/sunset times. They can also be easily turned on or off manually just by pressing the switch.

Personally, I find them more appealing than photocells since they provide more control and are easy to install. Also, at $25-$30, it's a cost effective alternative. But of course, you're the one who knows how you're going to use it - so the decision is up to you.
 
  #9  
Old 02-26-07, 09:22 PM
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Jhon,
Thanks, It just seems logical to me to have the PC then switch.
I guess it might be safer to have the pc after the switch then you always know the switch is line!!! Would it not be to code?????
The PC I am using is normally used in dusk to dawn lights for exterior security lighting. It would be ok if the light comes on in the day time for a short time (like the idea of seeing a burnt bulb before its dark!) I just don't want a delay at night when I hear a strange noise!!!
Should I just go and buy a PC for the flood lights?


zorfdt,
In my case its my backyard flood light and it is almost always turned on right before sunrise and then accidentally left on all day! I am tired of coming home right before dark only to see the light was on all day!!!
It doesn't have to be on at dark but I would like to be able to switch it on as needed and not have it be on all day.

Rickc
 
  #10  
Old 02-27-07, 07:12 AM
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I believe the delay in a photo sensor is only a delay in turning off. I don't believe there is any delaying in turning on. So I think you're covered either way in the event of a strange noise.
 
  #11  
Old 02-27-07, 04:12 PM
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Photocells have a built in delay in turning on or off. Some I have installed have stated "up to 5 minutes". That is so a dark cloud will not turn the light on and lightning flash will not turn them off.

The only salvation would be that most (if not all) PC's will turn the circuit on when they are first energized. After a minute or so they will react to the ambient light.

So, if the switch controls the PC, when you flip the switch, the light will light, even in the day. If dark, the light will then stay on until light.
 
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