How to Install a Photocell Sensor for Your Outdoor Lighting

What is a Photocell Sensor?

Automatic lighting, such as streetlights, often uses photocell sensors—also known as photoeyes—to sense how much ambient light there is. Once the photocell detects low enough light levels, the light turns on or conversely, rising external light levels will turn the light off.

The
photocell is made up of a resistor attached to photosensitive plates. As more
light hits the plates, the resistance (the amount of current that travels
through the resistor) changes, turning the light on and off. This technology is
convenient for all types of outdoor locations.

With no
user input required, there’s no concern about setting timers or forgetting to
turn the lights on. The photocell acts similar to how a light switch would—as
such, photocell sensors are also sometimes called photoelectric switches.

Photocells
work all year round, activating at dusk and turning off at dawn, even when the
days are longer in summer or shorter in winter. As they sense the amount of
light rather than operating at a set time, they don’t need to be adjusted when
sunrise or sunset shifts with the seasons.

Many outdoor lighting setups use motion sensors. However, photocell sensors and motion sensors typically serve different purposes. While a motion sensor might be useful to keep stray animals away from dumpsters and garbage cans, for example, a photocell can keep a parking lot safely and consistently lit for long periods of time.

How to Install a
Photocell Sensor for Outdoor Use

The following steps will guide you through
the installation of a photocell sensor. This project requires some electrical
work, so if you do not feel confident or safe performing these tasks, you
should contact an electrician to install the photocell for you.

  1. Turn off the circuit breaker to your outside
    light. If you do not know which breaker powers your light, turn off all
    breakers in the building to ensure that power is cut off. Double check that the
    power is off by flipping the switch to the outdoor light to make sure it
    doesn’t turn on.
  2. Disassemble the housing that contains your exterior light. You may want to document how it comes apart with photographs so that you can easily put it back together. 
  3. You should see two black wires on the photocell.
    Those black wires need to be tapped in to the black wire that runs between the
    light fixture and your structure’s main power. Disconnect the black wire going
    from the house to the light fixture.
  4. Connect one black wire on the photocell to the
    black wire that comes from the building. Be sure to twist the exposed copper
    wire so that it forms a tight connection.
  5. Connect the second black wire on the photocell
    to the black wire on your light fixture, making sure that the copper wire is
    twisted together completely.
  6. Cover the new connections you made with
    electrical caps. Ensure that the cap is tight around the wires.
  7. Tape your connections completely with electrical
    tape. Make sure that there are no exposed copper wires.
  8. To test the photocell, turn the power back
    on at the breaker. Make sure that the light switch is in the on position. Cover
    the photocell with your hand—if the light turns on when the photocell is
    covered, your photocell is working properly.
  9. Finish installing the photocell by putting your light fixture back together.

If you
are installing a new light fixture then the procedure is similar to the one
above. To install a new light fixture, you may need the following:

  • The
    new photoelectric switch
  • Wire
    strippers
  • Needle
    nose pliers
  • A
    screwdriver
  • A
    voltage tester
  • Electrical
    tape
  • Wire
    nuts
  • Silicone
    sealant 

Steps for installing a new fixture:

  • Turn
    off the power at the circuit breaker.
  • Remove
    the existing light fixture.
  • Install
    the new light fixture with the pre-installed photoelectric switch using the
    mounting instructions that come with it.
  • To
    wire your new light fixture, use your pliers to cut about 3/8" of
    insulation away from the wires. Twist together the black wire of the light fixture
    and the black wire of your house. Cover the new connection with a wire nut and
    make sure it is tight. Do the same thing with the white wires. Always connect
    black wires to black wires and white wires to white wires.
  • Cover
    all connections with electrical tape and tuck all the wires away.
  • Finish
    installing your light fixture per the manufacturer's instructions.
  • Once
    everything is assembled, test your light as shown above.

ATG
Electronics provides photocells that will fit in a variety of places,
including outlet boxes, post lamps, or outdoor lights. Our products are well
constructed and feature long service lives. If you are interested in photocells
for LED lighting, please contact us.