Photocell Light

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  #1  
Old 12-28-10, 07:09 PM
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Photocell Light

Our house has an outdoor motion-sensor floodlight under the carport. There is no switch installed.

I would like to install a photocell (perhaps just a socket...?) but I am wondering how sensitive they are to light. The end of the carport is quite shaded, at all times, and so I am wondering if I should install a separate photocell where the wires exit the side of the house near the roof. I am also worried that the socket photocell may be too shaded if I use it in a hanging fixture.

And, I assume installing these photocells isn't difficult? Just wire in hot and neutral to and from? Any conduit I have to use outdoors?

Thanks!
 
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Old 12-28-10, 07:20 PM
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Many motion sensors have built in photocells. Maybe just swap out the motion head?
Photocells mostly will not trip from just shade (except in stormy weather) Although I can't see your carport from here so I can't say for sure.

Wiring photocells are not tough. Most cases they are just 3 wires. Hot, Neutral and the switch leg. You have many choices for outside conduit. PVC, EMT with compression fittings, Liquid tight flex metal conduit (LFMC) , Non metallic flex conduit (LFNC) to name a few.
 
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Old 12-28-10, 07:57 PM
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Hmm...thanks. I'd like to completely replace the fixture (I hate the two floodlights -- ugly). I don't want it on with motion, either...just on at night. Probably a dumb question but what does the switch leg do? I guess I am confused because I thought the photocell acted as the switch.
 
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Old 12-28-10, 08:42 PM
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Probably a dumb question but what does the switch leg do?
No dumb questions. You correct the photocell is a switch. The switch leg is the wire from the photocell that is turned on and off. Another name for it is load side.
 
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Old 12-28-10, 08:49 PM
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Acting as a switch, what is the neutral for?
 
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Old 12-28-10, 09:00 PM
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Takes at least two conductors for an electric circuit to work. On the three wire photocell the neutral provides that second path. On cheap photocells there is no neutral and the path is through the light. That though only works on incandescent loads. Bulbs such as CFL will flicker even when off.
 
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Old 12-28-10, 09:09 PM
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Thanks. Still really don't get the whole neutral thing but I'm forcing myself not to dwell on it. If I install a photocell in an outdoor box here...I just cut the conduit and put the box in between, pulling through the wires from each side I assume?
 
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Old 12-29-10, 03:18 PM
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Well I only had a few minutes to investigate, but I also found another set of floodlights on the front of the house (not sure if they are motion or not...to dark to tell at the moment). However, none of the breakers were flipped in the box, but no voltage was going to the wires running under the carport. What should this tell me? Thanks...
 
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Old 12-29-10, 05:05 PM
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Originally Posted by JFS321 View Post
Well I only had a few minutes to investigate, but I also found another set of floodlights on the front of the house (not sure if they are motion or not...to dark to tell at the moment). However, none of the breakers were flipped in the box, but no voltage was going to the wires running under the carport. What should this tell me? Thanks...
It tells me you should start looking for a switch inside that controls power to the floodlights.
 
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Old 12-29-10, 07:22 PM
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Originally Posted by JFS321 View Post
Thanks. Still really don't get the whole neutral thing but I'm forcing myself not to dwell on it. If I install a photocell in an outdoor box here...I just cut the conduit and put the box in between, pulling through the wires from each side I assume?
For any device that uses electricity to work you need a complete path. From source, to load and back to the source. The hot is from the source. The neutral is the path back to the source and the load is the light, or in your case, the photocell. You have to power the electronics of the photocell some how so this is why you need a complete path. The switch leg is the wire that is switch by the photocell.

To install a box in the middle of an existing conduit run you will need to pull out the wires, install the box and then reinstall the wires and splice in the new box. You will then need to install some new wire from the box to the light because the old wires will be too short. Code requires at least 3" from the edge of the opening of a box but I like to have 6-8".
 
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Old 12-31-10, 02:54 PM
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Guys, thanks. My two outdoor lights were tied to the same breaker, but each was on its own circuit (I guess that's how I should say it). I spliced the wires in the attic and put them in a junction box. I would have obviously had to install the photocell before both lights, which would have required running some extra wire outdoors.

So, I did it the easy way and bought new floodlights with a motion sensor for one fixture, and a photocell socket adapter for the other.

Thanks for the help...I'm putting up another post about installing a wall switch now.
 
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