How to replace your old porch light with automatic (dusk till dawn) or motion sensor light

Written by darcy logan
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How to replace your old porch light with automatic (dusk till dawn) or motion sensor light
Adding an automatic light to your porch adds security and safety to your home. (Siri Stafford/Digital Vision/Getty Images)

Replacing your porch light with one that has a motion or dusk-to-dawn sensor is not any more difficult than replacing a basic light fixture. If your home was built before 1985, check with an electrician to ensure that your current wiring will work with newer fixtures and it is up to code. Once this is done, pick out a new light fixture. Before shopping, measure the mounting plate of the existing fixture. Your new one should be the same size or larger. Find a new light fixture that you like with a built-in motion sensor or dusk-to-dawn feature. If you can't decide, consider a fixture that offers both features.

Skill level:

Things you need

  • Measuring tape
  • Screwdriver
  • Wire stripper
  • Light fixture

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  1. 1

    Turn off the power to the fixture at the circuit panel.

  2. 2

    Unscrew and remove the bulb from the fixture.

  3. 3

    Unscrew the set screws or decorative nuts on the light fixture and pull it from the wall. Do not touch the wires.

  4. 4

    Use a voltage tester to test that the power is off. Touch one end of the voltage tester to the neutral or copper wire. Touch the other end to the black and then the white wire. If the tester lights up either time, the wires are still hot. Check the panel and turn off a different circuit. Repeat this step until the tester does not light up.

  5. 5

    Look at how the existing wire is connected. It should be black to black, white to white and grounding (green or copper) to grounding. If it is not, note which wire connects to which so you can repeat it. Since the wiring works, don't attempt to change it.

  6. 6

    Untwist the wires or wire caps and remove the old fixture.

  7. 7

    Check that the electrical box for the light fixture is the right size. In general, a light fixture needs an electrical box between 12 and 14 cubic inches. Plastic boxes should have their size stamped on them. To calculate the size of the box required, count any wires coming into the box and any clamps used. Add two for the light fixture. Multiply by two if using 14 gauge-wire or 2.25 for 12-gauge wire. If you're not sure whether your electrical box is large enough, consult an electrician. If the electrical box is not large enough, replace it before continuing.

  8. 8

    Strip the wires with a wire stripper so at least 1/2 inch of protective insulation is gone, if necessary.

  9. 9

    Run the wires through the gasket. Connect the grounding wires first. The ground wires may be solid copper or green. Twist the ends together and twist on a wire nut. Repeat with the black wires and white wires.

  10. 10

    Push the wires into the exterior junction box.

  11. 11

    Screw the fixture into place. Check that the rubber gasket is sealing up all the edges of the light fixture. If it is not, use clear silicone caulk around the edges to seal it. Wait to apply the caulk until after you have tested the light fixture.

  12. 12

    Adjust the motion detector or light settings, if necessary, and add a light bulb.

Tips and warnings

  • Read the directions provided by the manufacturer. Although all lights use similar installation techniques, check to see whether there are any special guidelines to follow.
  • Stop immediately if you do not find a grounding wire or if wire is dull grey (aluminium) instead of dull orange (copper). Both circumstances will require a licensed electrician.

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