Lamp post photocell hook up

Discussion in 'Electrical Forum discussion & Blog' started by mr fix it, Nov 16, 2009.

  1. mr fix it

    mr fix it New Member

    Messages:
    3
    Location:
    New Philadelphia, Ohio
    Hi: Question, I am hooking up a new outside lamp post with photocell dusk to dawn. I will not be hooking it up to electric supply till sometime next spring. Just putting everything together now. I am using conductivity meter to check wiring, everything seems to check out ok except I can not get a conductivity reading acrossed the photocell. I have reading going into cell black wire to black wire but no reading coming out the red wire to light
    I tried covering the cell with black tape and also after dark. Is it possible that conductivity can't be read acrossed a photocell??? Or does the photocell have to be exposed to the light for a day ??? I just took it out of the box. Thanks for any help.
  2. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    Photocells and the like are "electronic circuits" which need to be powered to function.

    And if there are any "diodes" (electronic component) in these electronic circuits, these would need a certain "voltage" (7/10 volt) and a certain "polarity" of voltage to get a reading on a testing device. Some testing devices do not provide this high of a voltage through the test wires.

    In English: Just follow directions, hook it up, and see if it works!
  3. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    A CdS photocell in bright light should read low (~10k?) resistance.
  4. mr fix it

    mr fix it New Member

    Messages:
    3
    Location:
    New Philadelphia, Ohio
    Thanks Billy Bob. That thought did enter my mind. Looks like I will need to power it up to see if it works. many thanks again for the help.
  5. mr fix it

    mr fix it New Member

    Messages:
    3
    Location:
    New Philadelphia, Ohio
    Thanks guy, everyone has been a big help. Nice to have the experts to take your problems too.
  6. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    The PV power from a 3 wire photo cell opens the circuit.

    When you first install and power up a 3 wire photo cell, the light will be on for about 20/30 seconds.

    It seems like you should have continuity between black and red (of the PC) right out of the box
    Last edited by a moderator: Nov 17, 2009
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