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Photo Sensor question??

Discussion in 'Electric Signs & Channel Letters' started by sigsignman, May 1, 2013.

  1. sigsignman

    sigsignman Member

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    Feb 2, 2010
    Bowling Green, KY
    Today and on a previous job, I installed a set of ul approved channel letters. In both cases, I added "photo sensors" and on both occasions they worked when I left...and when I checked back, they did not. These are 15amp photo sensors....Is it possible I am putting this on a 20 amp circuit and they are failing?...In both cases, it was on a set of LED Illuminated letters...any thoughts please?..the previous job, I removed the sensor and it worked fine...wtf?? thanks!
     
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  2. signage

    signage Major Contributor

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    Oct 5, 2005
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    Whats the drawl of the circuit after the photocell?

    Did you test the photocell after you removed it?
     
  3. sigsignman

    sigsignman Member

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    Feb 2, 2010
    Bowling Green, KY
    thanks for your reply...I always "thought" that a failed photo cell default was "on". How do you test a photo cell?...it was new in the box...but I know I've put in lots of fluorescent tubes that were "bad". We worked on the sign again today, I had a 2nd day employee work on it, removed some old circuit leads (to previous signs), hooked it up and had a dead short. We removed the top of the raceway and discovered that a wire got trapped, stripped and caused the dead short - a wire from the photo cell. Cut it, fixed it, hooked it back up. Turned on the breaker, immediately, it "lit"...and soon after turned off. I Thought it was fixed until I drove by in the dead of night tonight and it was not on again. I turned the breaker off and then back on...it did not turn on...I own British cars...so is it possible, the prince of darkness, Lord Lucas has cast its spell? (Gentlemen do not motor around at night)...lord Lucas
     
  4. xxtoni

    xxtoni Member

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    Jan 14, 2012
    We had a million little problems with photocells (or photoresistors as we call them).

    We never really identified the whole spectrum of problems but one of the more common ones was that the "head" of the photocell would corrode or something like that and would stop working because of that so that's something worth considering.

    We ordered a batch of the photo resistors that have a glass cover on them to see if they will perform better. We have yet to try them.
     
  5. J Hill Designs

    J Hill Designs Major Contributor

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    Sep 24, 2004
    the amp draw is close to nothing for LED PSU's so I doubt its overloaded. could be just a bad photosensor I suppose - to test, cover in 3 layers of elec tape, wait 15 min, and see if power is getting past it
     
  6. xxtoni

    xxtoni Member

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    Jan 14, 2012
    By the way we used ours for outdoor signs.

    Are your's for indoor or outdoor use ?
     
  7. signage

    signage Major Contributor

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    I would say the short fried the photocell switching circuit! And most all photo cells fail off (no power to device). Most of the newer ones a solid state!
     
  8. nwsigns

    nwsigns Member

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    Jan 13, 2011
    Monroe wa
    sign circuits are limited to 15A so you should be fine
     
  9. JS

    JS Member

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    Jul 19, 2006
    Channel Letters with photo cell

    There's a reason people hire qualified electricians. So they don't burn down the customers building. From reading this post it is clear you don't have much knowledge of electricity and installations of lighted signs. Channel letters are easy signs to install and hook up and if done properly the photo cells will work for years trouble free. People on a website CANNOT trouble shoot your electrical problem with the photo cell. Thats what TRAINED PROFESSIONAL electricians do. Give one a call and I bet in about 15 minutes he can fix the problem (as well as any other problems from the install). Stating the sign is UL is one thing but the simple fact that it was not installed from a qualified company is an oxymoron. Just my 2 cents....
     
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