Replacing Dusk To Dawn Photocell

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Mar 30, 2015
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Location
Lake Havasu City, Arizona
My front porch and garage lights are on a dusk to dawn photocell, ever since we have lived here. (Going on 5 years). They worked OK, but always seemed to turn on early, and off later than everyone else's. If we ever got heavy clouds, they would also turn on when no one else's did.

I just lived with it until yesterday. In the morning they turned off as usual. But I went out around 10:00 AM, (bright sunshine and clear skies), and when I came home they were on. My wife said she didn't touch the main ON / OFF switch next to the door.

So I "cycled" them by turning the main switch OFF, waited a minute, then turned them back on. They immediately turned on, and after about 2 minutes, shut off.

But enough was enough. So I went to Lowe's and bought a new photocell. This one, (except mine came with a new brushed Stainless Steel covering plate to replace the crusty old painted one).

https://www.lowes.com/pd/TORK-Photocell-Button/999910549

Now when I cycle them on, they only stay on for about 10 seconds, then shut off. They also turn on later than the old one. And turn off sooner, (like everyone else's).

But what I didn't expect is how much BRIGHTER the lights themselves are. I didn't think the photocell would, or could have any effect on the actual brightness of the lights themselves. The circuit would be either full ON, or OFF. But it did. Even my wife noticed it immediately, and asked me if I changed the bulbs.

I noticed the lens on the old photocell, (almost the same exact type), was clean, but very yellow when compared to the replacement photocell which was crystal clear. It is located in the porch ceiling, and never receives direct sunlight. So I'm guessing it was simply age and weathering.

Bottom line is if you have any type of issue, or weird things going on with these type of lights, replace the photocell right away, before you do anything else. It easy and cheap to do, (red to red, white to white, and black to black). And naturally, by just shutting off the main switch, you kill power to the line without having to turn off any breakers.

(Late edit). Be sure to check if you have the correct size wire nuts before you go buy the thing. I thought I had them, but didn't, and had to go back. Same deal with fresh electrical tape.
 
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Photo cells do wacky things when they are going bad. Once they develop a cataract their accuracy goes greatly. In most instances you can toggle a photocell within a 2-5 second power cycle to have the light stay on.

That’s a typical post mount style photocell with no adjustments photocells that are box mounted can be had with a slide window to make slight adjustments in the photocells operation.

I don’t know if the photocell has anything to do with light brightness that could have been more of a loose connection or corrosion within the connection.
 
"Technology Connections" on youtube has a fascinating 30 minute video on how these little things work.
I found this. This guy really knows his stuff! And he's way above my pay grade, that's for sure. But he does explain in great detail, why the lights, (a total of 4 LED bulbs), were less bright with the old, dying unit.

 
They have outdoor light bulbs with built in photo cells. I put several outside.

They have flood style, candelabra, and regular bulb.
I saw those when I was at Lowes replacing the photocell. They even have a few that are ON / OFF via motion detector. If my circuit wasn't already wired for a seperate photocell, these type of bulbs are the way to go.
 
I saw those when I was at Lowes replacing the photocell. They even have a few that are ON / OFF via motion detector. If my circuit wasn't already wired for a seperate photocell, these type of bulbs are the way to go.
At a church camp I helped do some electrical work, we replaced a flood light with motion detector with a LED photocell unit.

The motion detector face was covered in mold and one of the incandescent flood lights was half filled with water.
 
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