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Having outdoor security lights that reliably turn on at night is crucial for any home.
But how can you ensure your light sensors are actually working properly? Testing them is the only way to know if these essential fixtures will activate when you need them to.
As someone who once found my front door shrouded in blackness after the porch light sensor failed, I learned the hard way that untested sensors can unexpectedly stop working and leave you in the dark.
After that unsettling experience, I now make a habit of periodically testing all my exterior light sensors.
In this article, I will explain some easy methods for thoroughly testing your outdoor light sensors, so you never have to come home to a dark house again.
How to Test a Light Sensor?
When testing a light sensor during daylight hours, the goal is to simulate darkness to trigger the light to turn on.
This confirms that the sensor is working properly and able to detect changes in light levels.
One easy way to test a light sensor during the day is to completely cover it with your hand, a piece of cardboard, or even some tape folded over.
This blocks the ambient daylight from reaching the sensor, making it think it is nighttime.
When you notice the light turn on while the sensor is covered, you know the sensor is working correctly.
It’s a good idea to try covering the sensor from a few different angles when testing.
Some light sensors are very narrowly focused, while others have a wider range.
Covering straight on versus from the side can produce different results.
The light should activate whenever the sensor itself is shaded, regardless of the angle.
You may need to leave the sensor covered for 30 seconds or more before the light reacts.
There is often a slight delay built into light sensors to avoid false positives. Don’t remove your hand too quickly or you could miss the light turning on.
Besides using your hand or cardboard, you can also test by having a friend stand very close to the sensor to block the daylight.
Waving a hat in front of the sensor so it casts a shadow works too.
Even spray painting the sensor black is an option, though you’ll want to use removable paint.
Testing during bright daylight is ideal, because this is when the sensor has the most ambient light to detect.
However, you can test under cloudy skies as well. The light may take a few extra seconds to activate since the change in light levels is less pronounced on an overcast day.
While testing the light sensor, it’s a good idea to have someone standing near the light switch inside the home.
Let them know when you are about to block the sensor so they can watch for the light to turn on.
You can also just watch the light yourself if you have a clear line of sight.
Troubleshooting tip: If covering the sensor during the day isn’t making the light turn on, try cleaning the sensor lens with a soft cloth.
Dirt, dust or insect debris could be blocking it from detecting changes in light. If cleaning doesn’t help, there may be an electrical issue with the sensor or fixture.
For light sensors mounted high up on the eaves of a home, use a broom handle or pole to cover the sensor during testing.
You can tape cardboard to the end of the pole to shade the sensor more precisely. A tall ladder also works, though take proper safety precautions when working at heights.
Never look directly into a light sensor “eye” when testing as this can damage it. Work at an angle off to the side.
Also be careful not to touch any wires or electrical components inside the fixture while testing. The power should be turned off at the breaker to be extra safe.
If you have multiple outdoor lights with sensors, make sure to test each one. Sensors can fail over time, so just because one works doesn’t mean they all do.
Also, confirm the bulb in each light still works. Burned out bulbs are one of the most common reasons outdoor security lights fail to turn on.
Testing light sensors during daylight hours can feel silly pointing flashlights or waving cardboard at your exterior fixtures.
But this quick test can confirm if your sensors are functioning before you actually need them to activate at night for safety and security around your home.
Catching and replacing faulty sensors now means your lights will turn on reliably when it gets dark outside.
When to Test Your Light Sensor
Testing your outdoor light sensors periodically is important to ensure they continue working properly.
But how often should you test them? Here are some of the key times when you’ll want to verify your light sensors are functioning as expected:
When Outdoor Lights Are Activating At the Wrong Times
If your outdoor security lights are coming on during the day, during evenings when it’s still light out, or turning off randomly at night, the light sensors likely need adjustment.
Testing them will help troubleshoot why they are malfunctioning.
Too-sensitive sensors that activate with the slightest daylight changes can be annoying and reduce bulb life.
While sensors that turn lights off when it’s still dark out pose a safety risk. Testing will reveal if the current sensitivity settings are off or if the sensor itself is faulty.
When Lights Aren’t Coming On at Night
Outdoor lights controlled by light sensors rely on the growing darkness to automatically turn on. If your lights stay off at night, the first step is testing the sensors.
Faulty sensors that can’t detect dusk or darkness will never activate the lights. But before blaming the sensor, also check if the light bulb has burned out.
Dusk-to-dawn lights with non-functional bulbs can’t illuminate even if the sensor is working correctly.
It’s smart to test sensors seasonally since hours of daylight change. Sensors may need re-adjustment from summer to winter to keep lights off during the shorter days. Testing helps identify if program changes are needed.
When Installing New Light Fixtures with Sensors
Anytime you install new outdoor security lights with light sensors, take the time to test they are working right away. Don’t wait until nightfall to verify.
Testing upon install will confirm the new sensors activate properly when shaded and haven’t been damaged during shipping or installation.
If issues arise, you can troubleshoot and replace parts immediately under warranty rather than finding problems weeks later.
If replacing old sensor-enabled fixtures, reuse the previous light settings if known.
Sensors typically have dials or switches to control activation time and sensitivity. Replicating the old settings on the new fixtures provides continuity.
Periodic Testing Maintains Functionality
Make it a habit to test outdoor light sensors every 3-6 months. Periodic checks ensure your fixtures continue working and allow you to address problems before a failure occurs.
Sensors exposed to weather, changing seasons and electrical surges are prone to degradation and calibration issues over months of operation.
The functionality you verified six months ago could change as components age.
Don’t wait for a light to stop working before testing sensors. Take a proactive maintenance approach, even if the fixtures seem to be activating correctly night after night.
Scheduled testing provides peace of mind that your home’s exterior lighting remains reliable.
When Troubleshooting or Repairing Fixtures
Anytime you need to troubleshoot or repair an outdoor light fixture, take the opportunity to test its sensors are still working too.
If replacing a bulb or repairing electrical issues, don’t assume the existing sensors are fine. Test them while you have the fixture open.
Maintenance checks are the perfect chance to confirm proper sensor operation.
Small incremental sensor issues may go unnoticed for months until a total failure occurs.
Catching problems early by testing during repairs prevents bigger headaches down the road.
Before Going Out of Town
Test light sensors right before leaving for vacation to reduce home security concerns while away.
Knowing your exterior fixtures will activate reliably each night provides confidence. And if issues surface, you can address them before your trip.
Nothing is worse than coming home after a week away to find your outdoor lights never turned on at night as expected.
The peace of mind of testing right before vacation is worth the effort.
By making sensor testing part of your regular home maintenance routine, you can identify and rectify problems early.
Don’t wait until they stop working. Be proactive and test your light sensors periodically!
Testing the Light Sensor at Night
Testing a light sensor when it’s dark outside confirms it can detect the absence of daylight and activate the lights accordingly.
Here’s how to test that your outdoor light sensors work correctly at night:
The easiest way is to shine a bright flashlight directly on the sensor when it’s dark out. Caution – do not look directly into the light sensor or shine lasers at it.
But positioning a typical LED flashlight 6-12 inches away often works.
When a bright light shines on the sensor at night, it should detect the presence of “daylight” and turn the fixture off after a short delay, usually less than 1 minute.
If the light remains on even with a flashlight beam pointed at the sensor, that indicates a problem.
Troubleshooting tip: Try cleaning the sensor lens if it doesn’t respond to a flashlight at night.
Dirt or debris on the lens could be the culprit. Use a soft dry cloth or cotton swab dampened with rubbing alcohol to gently wipe the lens clean.
To test at night without a flashlight, have a friend or family member stand very close to the sensor to block its view and cast a shadow.
Waving a hand, hat or object near the sensor so it can’t see the night sky may also work.
As when testing during the day, it’s a good idea to try blocking the sensor from different angles – straight on, from the side, beneath, etc.
The light should turn off whenever the sensor’s “eye” is obstructed at night and can’t view ambient light.
For second story fixtures located high up, you’ll need a ladder or pole to reach the sensor at night unless you have a really bright flashlight.
Just be careful not to lose your balance leaning over while testing fixtures mounted along eaves or soffits.
Patience is key when testing at night. The light may not react instantly when you block the sensor.
Most have a built-in delay (typically 1-3 minutes) before switching off to avoid false alarms. Keep the sensor covered for a while to allow time for the fixture to turn off.
To make night testing easier, have a helper stand by the light switch indoors who can verify when the outdoor light turns off after you block the sensor.
Coordinate your efforts by phone or walkie-talkie. They can also confirm when the light turns back on after you uncover the sensor.
Troubleshooting tip: If the light doesn’t turn back on after uncovering the sensor at night, try adjusting the sensitivity dial or settings (if available).
Increasing the sensitivity should make the sensor respond better to light changes.
Inspect the sensor after testing to make sure the lens isn’t cracked or damaged.
Night testing requires physically blocking the sensor, so be gentle to avoid breaking it.
Also check that exposed wiring leading to the sensor remains intact.
Problems where the light stays on continuously at night even when shining a flashlight on the sensor indicate it may need replacement.
Most sensors cannot be repaired and must be entirely replaced. Make sure to turn off power before swapping in a new sensor.
While designed to operate automatically based on ambient light, most dusk-to-dawn light sensors also include an override switch that turns the light on/off manually.
Use this override function when testing at night to force the light ON after verifying the sensor turns it OFF when obstructed in darkness.
Testing light sensors at night is essential because issues and inability to detect darkness only surface after the sun goes down.
Replicating dark conditions is the only way to confirm sensors can properly activate the lights when needed for security and visibility around your home at night.
Periodically testing light sensors at night and during the day ensures 24-hour coverage so nothing gets missed.
Sensors exposed to weather, electrical surges, damage, and age can begin to fail at any time.
So schedule semi-annual testing to keep your exterior home lights shining bright all night long while avoiding false daytime activation.
Inspecting the Light Sensor Unit
The light sensor itself is a small device mounted inside or on the exterior light fixture. To thoroughly test its operation, you may need to remove the sensor unit for a close inspection. Here’s what to look for:
- Examine the plastic sensor housing for any cracks or damage. Cracks can allow water intrusion which can damage the internal electronics.
- Make sure the sensor lens appears clean and intact. Gently wipe with a soft cloth if dusty or dirty. Avoid scratching the lens during cleaning.
- Check that the wiring connected to the sensor is tightly fastened and the wires have no fraying or corrosion. Faulty wiring can cause intermittent sensor operation.
- Remove any cobwebs, insect nests, or other debris around the sensor housing. Spider webs can partially obstruct the lens.
- Ensure the sensor is securely mounted in its bracket and not loose or sagging. Loose mounting can disrupt alignment.
- Verify that the bracket or arm holding the sensor is still straight and firmly attached. Bent sensor arms will affect its directional accuracy.
- Confirm the sensor eye is pointed straight forward out from the fixture and not off angle. Skewed sensors can miss incoming light changes.
- Make sure the sensor has a clear line of sight and isn’t blocked by the fixture housing or other obstructions. An obstructed view reduces effectiveness.
- Inspect for any signs of water damage, rust, or corrosion on the sensor parts. Moisture penetration can occur over time on outdoor fixtures.
- Look for frayed or cracked wire insulation. Bare wires can short circuit which interferes with normal sensor operation.
- Check that the interior of the fixture is clean. Excessive dirt buildup can block some of the incoming light to the sensor.
- Make sure the light bulb is working properly and provides illumination when testing the sensor. Burned out bulbs make troubleshooting tricky.
- Read the manufacturer date sticker on the sensor housing to determine its age. Most light sensors last 5-10 years before needing replacement.
- Notice if any manufacturer part numbers on the sensor are faded or missing. This may indicate a non-original replacement part was installed improperly.
- Evaluate if a larger or smaller sensor eye is needed for your specific light fixture type and location. Proper sizing is key.
Carefully re-install the light sensor unit after completing inspection and any repairs. Take care not to over-tighten mounting screws or damage wiring. Restore power once fully reassembled and test for proper operation.
Inspecting and proactively maintaining light sensor hardware regularly is just as important as functional testing.
Physical problems like broken lenses, loose wiring, bent brackets, water corrosion, and excessive dirt can impair functionality over months of operation outside.
Look beyond just testing the sensor response by peering inside at the sensor device itself periodically.
Repair any minor issues noticed before they mushroom into major headaches or failures down the road.
Checking Light Sensor Settings
Most outdoor security light fixtures with dusk-to-dawn sensors have adjustable settings to control when the lights activate and sensitivity.
Checking these settings is an important step in troubleshooting sensor operation.
Consult the manufacturer’s manual to understand the available settings and how to adjust them on your particular light model. Settings may need tweaking seasonally as daylight hours change.
Here are some common light sensor settings to check:
Activation Time
A dial, switches, or digital menu typically controls when the light turns on as it gets dark, and off as it gets light.
Adjusting the activation time can help resolve issues of lights turning on too early or turning off too late.
Start with a medium setting then adjust in small increments as needed. Leaving lights on too long wastes electricity while too brief operation doesn’t provide enough illumination.
Sensitivity
This controls how readily the sensor reacts to changing light levels. Settings often range from low to high.
If your light reacts to passing car lights or activates on cloudy days, dial down the sensitivity.
Increase sensitivity if your light isn’t activating early enough at dusk or turning off late enough at dawn. Find the right balance for your location.
On-Time
On-time refers to how long the light stays on once activated at night before turning back off. This can usually be adjusted from 1-20 minutes, though durations will vary by model.
Choose an on-time long enough to deter prowlers but not so excessive your bulbs burn out prematurely from overuse. 10 minutes is typical.
Test Mode
Some sensors have a special test mode to override normal operation for troubleshooting.
This allows daytime testing without having to cover the sensor. Just be sure to deactivate when done.
Override Switch
Most sensors have a manual override switch that forces the light on or off. Use this override to manually turn the light back on after testing the sensor at night.
Photocell Disable
Higher-end sensors may allow disabling the photocell completely for troubleshooting. This forces the light on 24/7 regardless of ambient light conditions.
Don’t forget to restore normal photocell operation when testing is complete. Leaving the sensor disabled will waste energy and reduce bulb life if left on 24/7.
Beyond basic settings, some customizable options on newer digital sensors include:
- Separate on/off activation times
- Walkway feature for low-level night lighting
- Scheduling specific on/off times for certain days
- Automatic seasonal light level adjustments
- Radar motion detection enabling
- Remote lamp monitoring
- Smartphone app integration and control
Get familiar with the capabilities of your specific light sensors. Adjustments may be needed seasonally or if problems develop.
Settings can even be used creatively, like scheduling decorative landscape lighting to turn on only on weekends or holidays.
Don’t let improper sensor settings go uncorrected. A small adjustment could be all that’s needed to rehabilitate a poorly performing light sensor.
When to Replace a Faulty Light Sensor
Light sensors exposed to weather and electrical currents day after day often eventually fail. But when is it time to replace a faulty outdoor security light sensor?
If Testing Confirms Sensor Failure
First, thoroughly test the sensor using the steps outlined earlier. If covering the sensor day and night doesn’t activate the light, it likely needs replacement.
Also, replace right away if the light stays on continuously 24/7 after testing. However, first check the bulb hasn’t burned out before assuming the sensor is bad.
Age Over 10 Years
Most light sensors are rated to function properly for around a decade. If your sensor is 10+ years old, replacement may be worthwhile even if still partially working to preempt complete failure.
Previous Sensor Failure
If one sensor has already failed, the other fixtures likely aren’t far behind. All sensors installed around the same time experience similar environmental stresses.
Consider proactive mass replacement.
Moisture Damage
Visible corrosion, water intrusion, or mold inside the sensor housing are signs moisture has damaged the internal electronics.
Replace immediately in these cases before additional weather exposure occurs.
Intermittent Operation
Sensors that seem to work sometimes but not others need replacement. Proper operation should be reliable day after day.
Erratic behavior usually means the sensor is failing.
Faded Labeling
Severely faded manufacturer stickers on the sensor housing can hint the device is aged.
Harsh UV exposure over many years degrades the printing. If barely legible, the sensor has seen better days.
Estimate Based on Bulb Changes
If you’ve lost track of exact sensor installation dates, estimate age based on the number of bulb changes.
If you’re on your 5th or 6th bulb, the sensor is likely due for replacement after 8-10 years of operation.
Renovation Upgrades
Take the opportunity to swap light sensors when renovating that area of your home or upgrading outdoor fixtures.
Don’t keep an outdated sensor when installing new stylish fixtures.
WiFi Smart Lighting Conversion
For homeowners transitioning to app-controlled smart outdoor lighting, new WiFi-enabled sensors will be required to enable remote functionality.
Diagnosing Difficulties
If troubleshooting has proven tricky due to old sensors where functionality is questionable, replacement provides a fresh start with brand new units.
Reliability Prioritization
For exterior lighting crucial to home security, proactive sensor replacement avoids being left in the dark one night when an old sensor finally dies. Prioritize reliability with new parts.
Installing a new light sensor is typically simple for homeowners. Turn off power, unmount the old sensor, install the replacement, and restore power.
Most are “plug and play” once wired correctly. Consult a handyman or electrician if unsure.
With new light sensor technologies and options evolving yearly, upgrading old sensors can add exciting functionality like automated scheduling, motion detection, smartphone integration, remote lamp monitoring, and more.
Hiring an Electrician for Light Sensor Replacement
While a handy homeowner can potentially replace a faulty outdoor security light sensor themselves, it’s best to hire a licensed electrician if at all unsure about safely completing the work.
Lighting projects involve electricity, heights, and making sure the job is code-compliant.
Here are some signs it may be wiser to hand sensor replacement over to the pros:
You Lack Electrical Experience
If you don’t have much past experience working with wiring, electrical fixtures, basic electrical tools, and testing equipment, sensor swap-out may be challenging. Hire an expert rather than risking an electrical hazard through trial and error.
The Fixture Location is Dangerous
Light sensors mounted high up, over stairwells, on roof edges or other precarious locations should be handled by an experienced electrician with proper equipment. Don’t risk a fall or injury trying to reach difficult fixtures.
Your Home is Very Old
Older homes often have outdated, non-standard wiring that presents added hazards. Licensed electricians are the safest choice for homes with knob and tube wiring, aluminium wiring, braided cloth wiring, or other antiquated electrical systems.
You’re Unsure About Codes
Electricians ensure all work complies with NEC codes for proper fixture weatherproofing, clearance distances, permitted wiring, grounding, GFCI protection near wet areas, etc.
Don’t take any chances on code violations if DIY savvy is limited.
Multiple Sensors Must Be Replaced
For larger-scale sensor replacement jobs involving upgrading all outdoor fixtures, the workload may be daunting.
Electricians have the right tools and expertise to efficiently complete large-scale jobs.
Specialized Equipment is Required
Some sensor installations require lifting equipment, scaffolding, or other specialty gear homeowners likely don’t own.
Hiring pros with the right equipment for the job is sensible.
Permit Requirements are Unclear
Electricians know specifically when electrical permits and inspections are required by local codes for legal sensor replacement and lighting upgrades.
Don’t risk fines for unpermitted work.
You’re Uncomfortable Working Live
While power should be shut off at the breaker when replacing sensors, limited live testing is sometimes required. If working with live wires makes you nervous, hire an electrician who can work safely with live power.
Insurance Coverage is Needed
Homeowners insurance may require certified electricians complete any permanent electrical work to maintain coverage. Verify policy clauses and consider professional help.
Warranties Are Important
Many electricians provide warranties on parts and labor for electrical work. DIY provides no such protection if something fails shortly after the job.
For most homeowners, hiring an electrician to swap out a single outdoor security light sensor likely isn’t essential.
But if tackling the project gives you any reservations, get quotes from local licensed electricians to provide helpful professional assistance. Safety and proper workmanship is worth the investment.
FAQs
How Do You Test A Light Sensor With A Multimeter?
Using a digital multimeter (DMM) is one way to check a light sensor’s electrical function. Set the DMM to voltage measurement mode.
Attach the black probe to the sensor’s ground wire and red probe to the power wire. With ambient light present, it should show a voltage around 3-5V.
Block light to the sensor and the voltage should drop to 0.2V or lower when activated. Fluctuating voltage indicates erratic sensor operation.
A steady high or low reading could mean a stuck closed or open sensor.
How Do You Check If A Light Sensor Is Working?
The easiest way is to block light to the sensor with cardboard during the day. A working sensor will activate the light. At night, shine a flashlight on the sensor.
A properly functioning sensor will turn the light off. If the light doesn’t change when blocking or introducing light to the sensor, then it may not be working correctly.
Also watch the light at dusk – a working sensor will automatically turn the light on at the appropriate ambient light level.
How Do I Know If My Light Sensor Is Bad?
Signs of a bad light sensor include the light turning on randomly during the day, staying on all night, or not activating at dusk.
The light may flicker on and off instead of staying steady. You may need to tap on the sensor housing to get the light to come on.
A bad sensor will show no change in voltage output when light conditions change. Faded or missing labeling, moisture inside the housing, and age over 10 years can also indicate failure.
How Do You Measure A Light Sensor?
The measurement units for light sensors are lux and foot-candles. Lux is the metric measurement while foot-candles are imperial units.
Lux meters and foot-candle light meters are tools used to quantify the light readings. Smart light sensors can self-report lux values.
Measure the ambient light then introduce a bright flashlight and take a second reading – it should measure significantly higher lux with direct illumination present.
What Is The Input Voltage Of A Light Sensor?
Most light sensors run on 12V to 24V DC input voltage from the fixture wiring. Always check the specific sensor’s rating before applying power.
Providing the incorrect input voltage outside the specified range can irreparably damage the sensor components.
Polarity also matters – wire positive to the power pin and negative to the ground pin. Reversing the polarity will prevent the sensor from operating.
How Do You Check If All Sensors Are Working?
To check a group of light sensors, use the block and introduce light testing method on each fixture sequentially.
This verifies each sensor reacts properly to changing light conditions. For large sensor arrays, consider a wirelessly controlled tester that sends an activation signal.
When the light turns on, you know that sensor is working. Test during the day and at night to confirm 24-hour functionality.
What Are The 3 Common Causes Of Sensor Failure?
The three most common reasons light sensors fail are:
- Age – Sensors gradually degrade over 5-10 years until circuitry fails.
- Moisture – Water intrusion from outdoor exposure corrodes internal electronics.
- Dirt – Dust/debris blocks the sensor eye preventing light detection.
Other causes include loose wiring, power surges, physical damage, UV exposure embrittling plastic housings, thermal cycling, vibration, and insect infestations blocking the optic path.
What Activates A Light Sensor?
Light sensors activate when diminishing ambient light crosses below a preset lux threshold indicating dusk or darkness.
The light turns on automatically when the sensor detects low light levels. Introducing an opaque object to block light to the sensor during the day also triggers activation to simulate nighttime light conditions.
How Do You Troubleshoot A Faulty Sensor?
Start troubleshooting with a visual inspection of the sensor for damage and dirt obstructing the eye.
Test functionality by blocking and unblocking light during day and night. Check wiring connections and input voltage.
Adjust settings like activation time and sensitivity. If still nonfunctional, unmount the sensor and check for moisture damage or bugs/webs inside.
Faulty sensors will need replacement if confirmed dead after troubleshooting.
What Is The Output Of A Light Sensor?
When activated by decreasing light levels, the sensor output is an electrical signal that triggers the attached light fixture to turn on.
This is accomplished by closing a relay inside the sensor that allows current flow to the fixture.
Typical outputs are small low voltage DC signals under 24V and a few milliamps of current. The sensor output connects to a higher wattage relay that switches the main AC power.
How Do You Adjust A Light Sensor?
Consult the manufacturer instructions for your particular light sensor model for directions on how to adjust.
Settings like light activation level, on-time duration, dusk-to-dawn detection span, motion detection toggle, and lux measurement units are often adjustable via dials, switches or a software menu.
Make incremental adjustments while testing the impacts to avoid overcorrection.
What Is The Unit Of Light Sensor?
The measurement units for light sensors are lux for metric sensors and foot-candles for imperial sensors. One lux equals one lumen per square meter. One foot-candle is one lumen per square foot. Higher lux/foot-candle values indicate brighter light on the sensor. Sensors report ambient light in these units and activate fixtures below adjustable thresholds.
Conclusion
Testing your outdoor light sensors by blocking ambient light and shining flashlights is crucial to ensure they activate properly at night when needed.
Remember to periodically check sensor functionality during the day and at night, inspect the physical unit, adjust settings as needed, and proactively replace sensors every 5-10 years.
Taking just a few minutes to test your light sensors now can save you from being left in the dark down the road.
Make sensor testing part of your regular home maintenance routine for peace of mind that your exterior lighting will provide safety and security when you need it most.