Soffit floodlights © D Friedman at Security or Motion Sensing Light Install / Repair

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How to install or replace an outdoor floodlight, security light, or motion-sensor light.

Here is a photo-illustrated step-by-step guide to replacing an outdoor floodlight with a motion-sensor activated security light. The article describes each step from removing an old light fixture through selection of an electrical box, preparing the existing electrical wiring, connecting the new light fixture to the existing wiring, installing the fixture to the electrical box, and testing and adjustment of the motion sensor light.

This article series discusses outdoor lighting installation, troubleshooting and repair procedures. This series also explains how to install recessed lights in an exterior soffit or roof overhang. We provide lighting installation suggestions about the type of light fixture to use, light fixture support, clearances, fire safety, moisture resistance, switch location, and electrical code citations for exterior lighting on buildings.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

How to Install or Replace Outdoor Floodlights & Security Lights

Obsolete outdoor floodlight fixture to be replaced (C) Daniel Friedman

Mounting a repaired or new motion sensor light involves these steps. [Click to enlarge any image]

Article Contents

  1. REMOVE OLD LIGHT- Remove the old light fixture & inspect it to see what you can learn; leave the existing wires for their new connections
  2. MOUNT NEW ELECTRICAL BOX- select & mount a wet-location electrical box to wire the new light
  3. PREPARE NEW LIGHT FIXTURE - drilling out cover mounting holes may be necessary
  4. PREPARE WIRE ENDS for CONNECTION - stripping, cleaning, twisting, removing any oxidation or kinks
  5. WIRING CONNECTIONS - make the necessary line, neutral & ground wire connections & splices
  6. MOUNT LIGHT FIXTURE to ELECTRICAL BOX - assure a good fit between the light base, gasket, and edges of the electrical box then secure the light in place. Seal the electrical box to the building wall to be sure that we're not sending rain behind the box and possibly into it at its rear wiring port.
  7. POSITION & AIM the FLOODLIGHT approximately where you want the bulbs to illuminate the area; you may need to make these final adjustments at night in order to see the illumination pattern accurately.
  8. SELECT LIGHT SETTINGS - Adjusting the motion sensor field of view, range or sensitivity, and lights-on-time. Test that the light is operating properly using the motion sensor's TEST switch setting.

Remove & Inspect the Old Outdoor Light

A neighbour asked for help in replacing some outdoor floodlights that were not working. We agreed to replace the manually-switched outdoor lights with motion-sensor floodlights in some locations and wall-mounted lights in others.

The old and new wall-mounted floodlight photos and text here illustrate coping with the problems that come up when removing old and installing new outdoor security lights.

Sometimes just getting the old fixture off of the wall can be a challenge: painted-over screws, rust-jammed locknuts, obsolete electrical boxes can add time, trouble and cost to what the electrician bid as a quick swap-in job.

One of the floodlights in this wall-mounted fixture over a garage had stopped working. I tried replacing the bulb first to confirm that it wasn't something as dumb as having swapped in a bad floodlight bulb. Nope. I looked for a corroded or burned contact in the bulb socket base. Nope.

A closer look, though, revealed that the metal bulb socket was split. A trivial repair might have been to just replace the bad bulb socket assembly, re-attaching it to the existing electrical box. But other conditions (box too small, crowded, corroded, leaky, no room for an added motion sensor) at this light fixture argued for a complete replacement.

Split bulb socket caused failure of this outdoor floodlight (C) Daniel Friedman 2016

More details about troubleshooting an outdoor floodlight or security light that is not working are at REPAIR AUTOMATIC OUTDOOR LIGHT FIXTURE.

Watch out: do not attempt electrical work unless you are qualified as there are both fire and fatal electrocution hazards at risk. In many jurisdictions electrical work can be performed only by a licensed electrician. New work and some electrical repair work may also require a building permit, inspections, and approvals. Check with your local building department.

Obsolete outdoor floodlight fixture to be replaced (C) Daniel Friedman

A look at the existing box found it corroded, paint-jammed, and under-sized as well as leaking. To remove and replace the bulb socket on the existing box would be time-consuming and we'd end up with a light that was still switched on and off only manually. The little electrical box didn't include a mount opening to add-on a motion sensor and the box interior was too small to jam in more wires and twist-on wire connectors anyway.

Removing old outdoor security light (C) Daniel Friedman Removing old outdoor security light (C) Daniel Friedman

The ground wire needed to be disconnected from the ground screw. Then the hooked ends of the solid conductor wires needed to be straightened so that it would be possible to pull the wires out of the electrical box without damaging the insulation.

Removing old outdoor security light (C) Daniel Friedman Removing old outdoor security light (C) Daniel Friedman

When the wires were ready to be pulled out of the box we then loosened the strain relief clamp screws completely to give plenty of room to pull the wires out of the metal box.

Watch out: give yourself plenty of room to pull the wires out lest you scrape or cut the wire insulation. Below we see the lighting circuit at the wall, ready for mounting of a weatherproof electrical box and then the connection of a new motion-sensor light.

Removing old outdoor security light (C) Daniel Friedman

Select & then Mount the Electrical Box for the New or Replacement Motion Sensor / Security Light

I prefer to use metal outlet boxes designed for use in a wet location, but plastic boxes are also sold for that purpose.

Choice of plastic or metal wet-location electrical boxes (C) Daniel Friedman

[Click to enlarge any image]

In the photo below I'm showing a suitable wet-location box against the building wall with the connecting wires protruding through the opening at the back side of the box.

Missing in some of these photographs is the strain relief that would clamp the wires to the box.

Weatherproof wet-location electrical box test-fit against its mouonting location on a garage exterior wall (C) Daniel Friedman

Below: you'll need to install the screw-covers into all of the un-used openings in the sides of the electrical box. As our light fixture is going to mount to the box face, all four of the box side openings need to be closed against the weather.

Cover-screw for un-used openings on the electrical box (C) Daniel Friedman Cover-screw for un-used openings on the electrical box (C) Daniel Friedman

When the electrical box has been secured to the wall and its un-used openings closed, we're ready to mount the motion sensor light fixture.

Prepare the New Motion Sensor / Security Light Cover for Mounting

In addition to inspecting the new light fixture to identify and clean up the wires, check its intended mounting position against the mounting screw locations on the electrical box.

Watch out: When you've chosen which screw positions you're going to use on the electrical box (typically I use the 2 o'clock and 7 o'clock or the 5 and 11 o'clock positions) you need to take a look at the light fixture itself. Some wall-mounted motion sensor or security lights mount by screws passing through two holes in the light cover while other units use a cover center mounting screw that secures to a metal strap that must be installed in the electrical box.

But this security light that I was installing (shown below) required drilling-out the screw openings that were to be used in the fixture cover.

Light fixture with blind cover hole to be drilled out (C) Daniel Friedman Light fixture with blind cover hole to be drilled out (C) Daniel Friedman

That's probably so as to avoid other un-necessary holes and possibly leaks in the light fixture cover. Select a drill bit that's about the diameter of the cover opening template - it will need to be just larger than the diameter of the actual mounting screws. Check this now as if you forget and have wired the fixture up before discovering you need to drill the cover you'll be sorry: standing on your ladder and drilling into the air.

Inspect & Prepare the Light Fixture Wires

Below: here's what the wiring-side of the motion sensor light will look like when you remove it form the package. You'll want to find and clean-up the ends of the line (black), neutral (white) and ground (green) wires before trying to connect this fixture to the electrical box.

Wiring for motion sensor light SecureHome from Heath Zenith (C) Daniel Friedman Wiring connectors for a motion sensor light (C) Daniel Friedman

We're going to install a SecureHome motion sensor light control provided by HeathZenith.

Prepare the Existing Electrical Wires for Connecting to the New Light Fixture

I noticed that some of my existing solid copper wire ends were dark in color, oxidized from decades of occupancy in a leaky electrical box. That risks a poor electrical connection and could be unsafe or could cause the fixture to work only intermittently.

Oxidized solid copper wire needs cleaning before re-connecting. (C) Daniel Friedman Cleaning by sanding the oxidized copper wire end (C) Daniel Friedman

Below you can see the cleaned neutral wire conductor end.

Sanded oxide off of an oxidized solid copper wire (C) Daniel Friedman

While it's true that a twist-on connector's internal spring may cut through the oxide, I want my current to flow wire-to-wire, not wire to connector spring to wire. So for best results, the solid-conductor electrical wires need to be straight and clean before they can be inserted into a twist-on connector.

Straightening a bent solid copper wire end for use in a twist-on connector (C) Daniel Friedman

Above: some wire ends were bent and irregular in shape. Inside a twist-on connector that can make for a bad connection or even an impossible one. I use my pliers to straighten out kinked solid copper wire ends to prepare them. If the wire end is badly damaged I'll simply cut it off and strip back insulation to make a new stripped-wire end.

Make the Security Light Wire Connections in the Electrical Box

Wiring Diagram for a Typical Motion Sensor or Security Light

The installation instructions include this simple schematic illustration (adapted with added remarks) show how the motion sensor light assembly will mount to the weatherproof electrical box once that box is in place on the wall.

Example mounting of motion sensor light to  wet-location weatherproof electrical box (C) adapted from Health Zenith

Watch out: don't forget to route the electrical wires through the inside of the gasket or you'll have to take everything apart and start over. Our green ground wire shown in the sketch above needs to be re-routed through the gasket opening.

Three Hands: Hold that Motion Sensor Light & Don't Fall off the Ladder

How to Hold the light fixture, the wires, your tools and your place on the ladder when wiring up a wall or ceiling light fixture:

Plastic light suspension gimmick helps install a wall or ceiling light fixture (C) Daniel Friedman

Some manufacturers provide a cute little plastic cable with the light fixture. One end of the cable secures to the metal strap to which the light fixture is going to mount while the other secures to a center mounting screw opening on the light fixture itself. That lets you hang the fixture from the plastic support while making your connections.

Light fixture hanging from the ground wire (C) Daniel Friedman

If you don't have three hands and are up on a ladder working alone, another approach is to connect the ground wires first, hang the fixture from that connection (green arrow in the photo above), make the other hot and neutral connections, check that the ground connection hasn't come loose, then mount the fixture.

Watch out: the outdoor light wiring shown above is improper and unsafe as there is no wet-location or weatherproof electrical box being used. Of course we corrected this fiasco and we also sealed the new fixture's electrical box to the building wall. .

Ground Wire Connections at the Security Light

Below: the circuit grounding conductor, bare solid copper, is going to be connected to both the grounding screw in the metal electrical box AND by twist-on connector (not shown) it will connect to the light fixture's own ground wire.

Connecting ground wire to both metal electrical box and the light fixture ground wire (C) Daniel Friedfman

Just below in another example of ground connections at an outdoor light, the installer is using a crimp-type connector instead of a twist-on connector to join the circuit ground to the light fixture ground.

Connecting fixture  ground to circuit ground at a  motion sensor light (C) Daniel Friedman Connecting fixture  ground to circuit ground at a  motion sensor light (C) Daniel Friedman

If you use this connector you need to use the proper crimping tool for reliable results and even so I'd tug on that multi-stranded wire to be certain that it's securely bound. The solid conductor ground in the photo also needs to be connected to the ground screw in the electrical box, and again.

Missing strain relief clamp?

Some electricians will comment that the strain relief for the entering wires is missing in the photos above. IF this outside electrical box is being mounted over a pre-existing in-wall-cavity electrical box that includes a strain relief for these wires your electrical inspector may accept this installation as shown.

Mating multi-strand wires that are going to be inserted into the twist-on connector also need to be prepared by twisting the stripped wire ends clockwise. Why clockwise? So that when you twist the twist-on wire connector cap clockwise to tighten it you won't be un-raveling the multi-strand wire inside the cap.

Multi-strand wire  from the light fixture needs preparation  before it can be inserted into the twist-on connector (C) Daniel Friedman Multi-strand wire  from the light fixture needs preparation  before it can be inserted into the twist-on connector (C) Daniel Friedman

If you're wondering why I keep saying "twist-on-connector" instead of the widely-used term "wire nut" it's because Wire Nut™ is a registered trademark for a specific brand of twist-on connectors - though like "Kleenex" for "Tissues" the term has become so widely-used as to be rather generic.

Line & Neutral Connections at the Motion Sensor Light

Below I'm joining the neutral wire of the light fixture to the lighting circuit neutral wire using a twist-on connector or wire-nut. I'm using the twist-on connector provided by the light-fixture manufacturer in this case.

Twisted multi-strand wire and solid conductor wire ready to be spliced together using a twist-on connector or wire nut (C) Daniel Friedman Twisted multi-strand wire and solid conductor wire ready to be spliced together using a twist-on connector or wire nut (C) Daniel Friedman

The two wires are stripped to equal length and not so stripped that bare wire will be exposed after the twist-on connector is in place. I hold the ends parallel, insert them into the connector, and twist it firmly clockwise.

Note for U.K. readers: you will rarely see "wire nuts" or twist-on connectors on electrical circuits in the U.K. That's because most U.K. residential electrical circuits for lighting and receptacles are wired as a "ring circuit" rather than as a "radial/spur" circuit. Fewer wire splices are required. And where splices are required on U.K. circuits often the electrician uses a dedicated electrical joint box in which the wire splices are made using a connector strip rather than individual splice connectors.

Placing the spliced security light wires into the outdoor electrical box (C) Daniel Friedman

I might tug the wires or at least inspect my splice for good wire contact before then pushing the joined electrical wires into the electrical box.

I like to make only rounded gentle bends in electrical wires to reduce the chance of wire damage, and I place wires into an outdoor electrical box always with the wire nut tip facing "up" so that if water should leak into the box it'll drip off of the wire loops and not wet the wire connections themselves. In the original, too-small electrical box for the older floodlight you'd have no space for such fanciness.

Mount the Wired Motion Sensor Light to the Electrical Box

Outdoor motion sensor light mounting gasket  ready for mounting (C) Daniel Friedman Proper gasket placement when mounting a motion sensor light (C) Daniel Friedman

Watch out: as shown above, check again that all of your wires are passing from the motion sensor light fixture through the center of the fixture mounting gasket. Otherwise you won't be able to mount the light fixture to the electrical box without pinching wires around the gasket and ruining the weather-tight seal - and probably you'll ruin the wires too.

Outdoor motion sensor light mounting gasket  ready for mounting (C) Daniel Friedman

Align the security light fixture mounting holes first with the gasket holes, and next with the appropriate mounting holes on the electrical box, then insert the screws and mount the light.

Light gasket in place  before tightening the security light mounting screw (C) Daniel Friedman

Watch out: before tightening the screws completely look and feel around all edges of the electrical box to be sure that the gasket is neatly in place. If the gasket has gotten pushed inside the electrical box rather than being pinched between the fixture mounting plate and the electrical box edges then the box will leak, risking short circuits, unsafe conditions, light failure.

Adjust the Position or Aim of the Motion Sensor Light Floodlamps

Screw to loosen to change the flood light sweep angle (C) Daniel Friedman

There are two different position-adjustment mechanisms on a typical floodlight or motion sensor light. Above I'm loosening the screw that allows the lamp socket to rotate away from the building.

Screw to loosen to change the flood light sweep angle (C) Daniel Friedman

A second adjustment allows adjustment of the angle of the lamp socket by loosening the larger-diameter lock nut around the lamp socket base. Tap this screw counter-clockwise to loosen it and clockwise (as in the photo) to tighten it once you've got the lamp socket aimed about where you think you want it.

Below is our new motion sensor light mounted, roughly-aimed, and ready for adjustment and testing.

You may need to fine-tune both of these lamp socket positions once again when you have seen just where the lights are aimed in darkness. Of course you'll need to install two outdoor-use rated floodlamp bulbs before the light will do anything interesting.

Motion sensor security light in mounted position (C) Daniel Friedman

The position or aim of the motion sensor, shown between the two lamp sockets in proper orientation above, is also adjustable so that you can control the security light's motions sensor field of view of what it "sees".

Seal the Electrical Box at the Wall

For added durability and safety, after your wall-mounted security light has been installed, use a good grade exterior sealant or caulk to seal around the electrical box where it contacts the building wall. I leave a tiny opening in the 6-o'clock position so that should any water seep behind the electrical box it can safely drain out onto the building wall below.

Adjust the Motion Sensor Light Features: Range, On-Time, Light Level

Adjustment instructions for a motion sensor light  - at On the bottom of the motion sensor you'll find one or more adjustable controls that are security or motion sensor light model-dependent.

[Click to enlarge any image]

You may also find a "test" switch or a "test" position on the time-on switch. Use switch position to keep the light ON during light angle or aim adjustment.

Shown here are instructions for HealthZenith's SecureHome™ motion sensor light control model # 5412. Your light model and features may, of course, differ.

Generally we can set these motion sensor light features, each of which is embossed into the plastic of the motion sensor and each of which will be detailed in the installation guide for your light.

  1. The motion sensor sensitivity or range
  2. The on-time when the security light senses motion. A slide switch on the sensor's base will typically show ON-TIME position settings of 1, 5, or 10 minutes as well as a TEST position that is used to check that the light is working even in daylight and thus it will allow you to check the sensor's response to nearby motion.

    On this light fixture "TEST" will cause the light to turn on and remain on for 5 seconds to allow adjusting the sensor's position and range.
  3. A dusk/dawn feature on some lights that leaves the light on at low intensity from dusk to dawn. When the light senses motion the light will switch to high intensity illumination.
  4. AUTO / MANUAL feature: Some sensors include a MANUAL switch that will turn the light on continuously until the next dawn. At night you can manually force this security light to remain "ON" by flipping the controlling light switch (wall-toggle-switch) off for one second, then back to on. The light will remain ON until the ensuing dawn. Then the light will reset to AUTO mode.

I want a driveway or garage entry security light to do several things, but these adjustments are somewhat subjective and are site-dependent.

Source of the new motion-sensor light used in this discussion:

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Article Series Contents

Also see our discussion of lighting requirements over stairs, at LIGHTING OVER STAIRS & AT EXITS and see LIGHTING, INTERIOR GUIDE for details about lighting fixtures, bulbs, and indoor requirements.

Also see our discussion of lighting requirements over stairs, at LIGHTING OVER STAIRS & AT EXITS and see LIGHTING, INTERIOR GUIDE for details about lighting fixtures, bulbs, and indoor requirements.


Continue reading at LIGHTING, EXTERIOR GUIDE - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.





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