A common CCTV complaint is:

“The camera works normally, but when LED lights are switched on, strange lines, flickering, moving dark bands, brightness changes, or unusual colors appear on the CCTV screen.”

Another related situation occurs when a CCTV camera is pointed toward a TV, computer monitor, LED display, digital signboard, or LED advertising panel. To the human eye, the display looks perfectly normal, but on the CCTV footage it may show:

• Black or dark horizontal bands
• Bright moving bands
• Flickering
• A screen that appears to switch ON and OFF
• Part of the screen becoming dark
• Strange colors
• Rolling lines
• Broken or incomplete images
• Brightness pulsing
• Wavy patterns
• Stripes
• Screen tearing-like effects

This does not automatically mean that the CCTV camera, DVR, NVR, TV, or LED light is defective.

In many cases, the cause is a mismatch between the way the light/display produces light and the way the CCTV camera captures individual video frames.

However, LED equipment can also create electrical and electromagnetic interference, so it is important to distinguish between optical flicker and actual electrical interference.

1. Why Can Our Eyes See a Normal LED Light While CCTV Sees Flickering?

The human eye and a CCTV camera do not observe light in exactly the same way.

An LED lamp may appear to produce continuous light, but electrically its output may actually be changing extremely rapidly.

For example, an LED driver may produce light output that varies:

Bright → Dim → Bright → Dim → Bright → Dim

This can happen dozens, hundreds, or thousands of times per second.

Our visual system may integrate these rapid changes and perceive apparently continuous illumination.

A camera, however, captures light during specific exposure periods.

If the camera exposure occurs at different points in the LED's brightness cycle, one frame may be bright and the next may be darker.

The result can be visible CCTV flicker.

2. LED Lights Do Not Always Operate Like Traditional Incandescent Bulbs

An incandescent bulb has a heated filament.

Because the filament remains hot between AC cycles, its light output changes relatively smoothly.

LEDs work differently.

LEDs require electronic circuitry known as an LED driver.

A typical LED lamp may contain:

230 V AC input → Rectifier → Filtering Circuit → Switching/Current-Regulation Circuit → LEDs

The quality of this driver has a major influence on how stable the light output is.

A well-designed LED driver may produce very low visible modulation.

A cheap or poorly designed driver may produce significant ripple or PWM-related flicker.

This may not be obvious to the human eye but can become extremely obvious to a CCTV camera.

3. Role of 50 Hz Electricity in India

India normally uses an AC mains frequency of approximately 50 Hz.

With some rectifier-based LED circuits, the light output can contain significant modulation at approximately twice the mains frequency:

50 Hz × 2 = 100 Hz

Therefore, an LED lamp may effectively produce a brightness pattern containing a strong 100 Hz component.

A CCTV camera simultaneously operates using parameters such as:

• Frame rate
• Exposure time
• Electronic shutter
• Sensor readout
• Anti-flicker frequency

If these parameters are poorly synchronized with the lighting environment, banding or flicker can appear.

4. What Is CCTV Banding?

Banding refers to visible bright and dark regions across an image.

You may see something resembling:

Bright area

Dark band

Bright area

Dark band

The bands may remain almost stationary or move vertically through the image.

Users commonly describe this as:

• Rolling line
• Moving line
• Black line
• Shadow moving across screen
• CCTV waves
• CCTV screen running
• Camera flickering
• LED disturbance

Banding is especially common with CMOS cameras because of their sensor readout method.

5. Rolling Shutter Is an Important Reason

Most modern CCTV cameras use CMOS image sensors.

Many CMOS sensors use a rolling shutter.

This means that the complete image is not necessarily captured at exactly the same instant.

Instead, different rows of pixels are exposed/read sequentially.

Conceptually:

Row 1 → Row 2 → Row 3 → Row 4 → ... → Final Row

Suppose an LED changes brightness while these rows are being captured.

The upper portion of the image might be captured while the LED is bright.

The middle portion might be captured while the LED output is lower.

The bottom portion may again be captured during another part of the cycle.

The resulting frame can therefore contain horizontal bright and dark bands.

This is one reason why LED flicker that is invisible to a person can look dramatic on CCTV footage.

6. Why Does Changing CCTV Shutter Speed Affect the Problem?

Camera shutter/exposure determines how long the sensor collects light for each exposure.

Examples could include:

• 1/25 second
• 1/50 second
• 1/100 second
• 1/250 second
• 1/500 second
• 1/1000 second

A very fast shutter captures a short slice of time.

This can make LED modulation much more visible.

For example, at 1/1000 second, the camera observes only a tiny portion of the LED's brightness cycle.

Consequently, high shutter speeds may increase visible banding under certain LED lights.

Longer exposure times average more of the light's fluctuations and may reduce the apparent flicker.

However, slower shutters can introduce motion blur.

Therefore, CCTV configuration involves a trade-off between:

Flicker reduction ↔ Exposure ↔ Motion blur ↔ Frame rate

7. What Is the Anti-Flicker or Anti-Banding Setting?

Many CCTV cameras provide settings such as:

Anti-Flicker

Anti-Banding

Power Line Frequency

Flicker Control

Exposure Frequency

Typical options include:

• 50 Hz
• 60 Hz

For installations in India, 50 Hz is normally the appropriate starting setting because the mains supply is 50 Hz.

Countries using 60 Hz electricity will normally use the 60 Hz option.

This setting helps the camera choose exposure timing that reduces interference between the camera and mains-powered lighting.

8. Important: Do Not Confuse Frame Rate with Mains Frequency

A common misconception is:

“India uses 50 Hz, so the camera must record at 50 FPS.”

That is incorrect.

50 Hz refers to the AC electrical supply frequency.

FPS means video frames per second.

They are different parameters.

A CCTV system might operate at:

• 15 FPS
• 20 FPS
• 25 FPS
• 30 FPS

while still having its anti-flicker configuration set to 50 Hz.

9. Why Does a TV Screen Look Strange Through a CCTV Camera?

This is another very common phenomenon.

A television or computer display may look perfectly stable to your eyes.

However, point a CCTV camera toward it and you might see:

• Black bands
• Moving lines
• Partial screen darkness
• Flicker
• Brightness changes
• Strange colors
• Image breakup

This happens because the display and camera have independent timing systems.

For example, a display may refresh at:

60 Hz

while the CCTV camera may record at:

25 FPS

with a particular shutter/exposure timing.

The camera therefore samples the display at different phases of its refresh cycle.

The mismatch can produce moving bands or flickering.

10. LED TVs Do Not Illuminate Every Pixel in a Perfectly Continuous Way

Modern televisions use technologies such as:

• LCD with LED backlighting
• OLED
• Mini-LED
• Different backlight dimming technologies

Many displays control brightness through high-speed modulation, scanning, or refresh mechanisms.

A camera can detect these timing characteristics.

Therefore:

TV looks normal to human eye

but

TV looks flickering or striped through CCTV

can be completely normal.

It does not necessarily indicate a defective television.

11. PWM — Pulse Width Modulation

PWM is especially important when understanding LED flicker.

PWM = Pulse Width Modulation

Instead of continuously reducing voltage to lower brightness, an LED can be switched ON and OFF rapidly.

For example:

Full brightness

ON ON ON ON ON ON ON ON

Lower brightness

ON OFF ON OFF ON OFF ON OFF

Very low brightness

ON OFF OFF OFF ON OFF OFF OFF

Because this happens rapidly, the human eye may perceive a steady but dimmer light.

A camera with a fast shutter may capture the individual ON/OFF periods.

This produces visible flickering or bands.

12. Why Dimmable LED Lights Can Cause More CCTV Problems

LED dimmers may use:

• PWM
• Phase-cut dimming
• Electronic switching
• Smart control circuits

At lower brightness settings, modulation may become more noticeable to cameras.

Therefore, if CCTV flicker occurs near a dimmable LED:

Test the light at 100% brightness.

If the CCTV problem disappears or significantly decreases, the dimming mechanism is probably involved.

13. Cheap LED Drivers Can Make the Problem Worse

Two LED bulbs that appear equally good to the human eye can behave very differently on CCTV.

A better-quality LED driver generally has better:

• Filtering
• Current regulation
• Ripple control
• EMI suppression
• Power-factor circuitry
• Component quality

Low-cost drivers may have significant output ripple.

Therefore, replacing the LED bulb with a better-quality flicker-controlled product can sometimes solve the CCTV problem without changing the camera.

14. Optical Flicker vs Electrical Interference

This distinction is extremely important.

There are two fundamentally different problems.

Problem A — Optical Flicker

The camera is physically seeing the LED's varying light output.

Typical symptoms:

• Horizontal bands
• Image pulsing
• Moving dark bands
• Problem only under certain lights
• Problem changes with shutter settings

Possible solutions involve:

• Anti-flicker setting
• Shutter adjustment
• Different LED driver/lamp
• Different lighting configuration

Problem B — Electrical or Electromagnetic Interference

The LED driver generates electrical noise that enters the CCTV system.

Typical sources include:

• Poor LED SMPS
• Poor earthing
• Common power wiring
• Ground loops
• Cheap power supplies
• EMI from switching electronics
• Poor-quality CCTV cable
• Improper cable routing

This requires a different troubleshooting approach.

15. How an LED Driver Can Electrically Interfere with CCTV

LED drivers are switching power supplies.

High-frequency switching can generate:

EMI — Electromagnetic Interference

and

RFI — Radio Frequency Interference

Noise can enter a CCTV installation through:

• AC power lines
• CCTV power adapters
• Common earth
• Coaxial cable
• Poor connectors
• UTP cable
• Nearby electrical wiring
• DVR power supply

This is especially important in analog CCTV technologies such as:

• CVBS
• AHD
• HD-TVI
• HD-CVI

Electrical noise can create:

• Horizontal lines
• Wavy patterns
• Moving bars
• Grain
• Image instability
• Color disturbance

16. How to Determine Whether the LED Is Optically or Electrically Affecting the Camera

A useful practical test is to cover the camera lens.

Test

Switch the problematic LED ON.

Completely cover the camera lens so that no LED light can enter.

Observe the CCTV video.

Interpretation

If the interference disappears:

The problem is likely optical — LED flicker interacting with camera exposure.

If the lines remain:

Electrical interference, grounding, power supply noise, cabling, or EMI becomes more likely.

This is a very useful field troubleshooting test.

17. Another Useful Test — Switch the LED Off

Observe the CCTV picture with the LED ON.

Then switch the LED OFF.

If the problem immediately disappears, the LED installation is strongly implicated.

However, this alone does not establish whether the cause is optical flicker or electrical interference.

The lens-cover test can help differentiate the two.

18. Test the Camera Using a Separate Power Source

For a 12 V DC camera, temporarily use a known-good separate CCTV power adapter.

Do not power it from the same questionable supply.

If the interference disappears, investigate:

• CCTV SMPS
• DC distribution
• Voltage drop
• Common ground
• Power cable
• Connectors
• Earthing

For PoE cameras, testing another PoE switch/injector can provide similar diagnostic information.

19. LED Lights Can Also Cause Overexposure

Not every LED-related CCTV problem is flickering.

A powerful LED lamp pointed toward a camera can create:

• White patches
• Washed-out image
• Loss of facial detail
• Glare
• Lens flare
• Reduced contrast

The camera may compensate for the bright light by reducing exposure.

This can cause the rest of the scene to become very dark.

20. WDR Can Help in High-Contrast Situations

WDR = Wide Dynamic Range

WDR is useful when a scene contains both very bright and very dark areas.

For example:

Bright LED signboard + dark entrance

Without WDR:

• Signboard may be readable but person is dark

or

• Person is visible but signboard is overexposed

A good true-WDR camera can combine exposure information to preserve more detail in both areas.

However, WDR is not a universal cure for LED flicker.

Flicker and dynamic range are different problems.

21. What Is BLC?

BLC = Backlight Compensation

BLC helps when the subject is dark because a strong light source is behind it.

Example:

A person stands inside a building entrance while bright outdoor light is behind them.

BLC increases exposure for the subject.

But the bright background may become overexposed.

22. What Is HLC?

HLC = Highlight Compensation

HLC attempts to reduce the impact of extremely bright light sources.

It can be useful for:

• Vehicle headlights
• Strong spotlights
• Bright lamps

HLC may improve visibility around the bright source but should not be confused with anti-flicker.

23. Why LED Signboards Can Look Terrible on CCTV

LED advertising displays contain thousands of rapidly controlled LEDs.

The LEDs are often driven through:

• Multiplexing
• PWM
• Row scanning
• Column scanning
• Refresh cycles

A person's eye integrates this activity into a continuous image.

The CCTV camera may capture only part of the refresh process.

The sign may therefore show:

• Black bars
• Missing sections
• Flickering text
• Half-displayed graphics
• Moving lines

This is particularly common with fast camera shutter speeds.

24. Why Mobile Phone Cameras Also Show This Effect

You may have noticed the same phenomenon when recording:

• LED bulbs
• Computer monitors
• Televisions
• LED signboards
• Car LED lights

using a smartphone.

Dark lines may move through the video.

This demonstrates that the effect is not exclusive to CCTV.

It results from the interaction among:

Light modulation + Display refresh + Camera shutter + Sensor readout + Frame rate

25. Can IR LEDs Cause CCTV Problems?

Infrared LEDs introduce another set of issues.

Night-vision CCTV cameras contain IR LEDs around or near the lens.

At night, IR can reflect from nearby surfaces such as:

• Glass
• Walls
• Metal
• Spider webs
• Dust
• Rain
• Fog
• Camera housing

This can create:

• White haze
• Circular reflections
• Washed-out images
• Bright spots

This is different from mains-frequency LED flicker but is often mistakenly described as an “LED problem.”

26. CCTV Behind Glass — IR Reflection

If an IR CCTV camera is installed behind a window, its own IR LEDs can reflect from the glass directly back into the lens.

The result may be an almost unusable night image.

Possible solutions include:

• Disable built-in IR
• Use external IR illumination outside the glass
• Move the camera outside
• Position the lens very close to the glass
• Prevent internal reflections

27. Can LED Lights Affect IP Cameras?

Yes.

An IP camera can experience optical LED flicker exactly as an analog camera can.

However, analog CCTV is often more susceptible to certain forms of signal-path electrical interference.

For an IP camera, investigate:

• Camera exposure
• Anti-flicker setting
• Ethernet cabling
• PoE voltage/power
• PoE switch
• Grounding
• Nearby electrical wiring
• LED driver EMI

Do not assume that an IP camera is immune simply because video is transmitted digitally.

28. Can a PoE Switch Cause Similar Lines?

A faulty or poor-quality PoE switch or injector can create camera instability, although the symptoms may differ from classic analog interference.

Possible effects include:

• Camera restarting
• Video freezing
• Packet loss
• Intermittent connection
• Night-time rebooting when IR activates
• Image instability

Check:

• PoE power budget
• Cable length
• Cable quality
• RJ45 termination
• Voltage/power availability
• Switch condition

29. Cable Routing Is Important

Never unnecessarily run CCTV cables directly alongside high-power electrical cables.

Maintain reasonable separation from:

• 230 V AC wiring
• LED driver cables
• Motors
• UPS output cables
• Inverters
• Transformers
• Heavy electrical equipment

If CCTV and AC cables must cross, crossing approximately at right angles is generally preferable to running them parallel for long distances.

30. Ground Loop Interference

Analog CCTV installations can suffer from ground loops.

A ground loop occurs when equipment connected at different points has different ground potentials.

Current can then flow through unintended paths, including video shielding.

Symptoms may include:

• Horizontal rolling bars
• Wavy image
• Hum bars
• Slowly moving lines

The appearance can sometimes resemble LED flicker.

Therefore, do not immediately blame the LED lamp.

31. Practical Troubleshooting Procedure

When LED lights appear to disturb CCTV, follow a structured process.

Step 1 — Switch the LED OFF

Check whether the image becomes normal.

Step 2 — Switch the LED ON

Confirm whether the disturbance returns.

Step 3 — Cover the camera lens

Determine whether the interference is optical or electrical.

Step 4 — Check Anti-Flicker

For India, start with:

50 Hz

Step 5 — Test Camera Exposure/Shutter

Try appropriate shutter/exposure settings rather than leaving an excessively fast fixed shutter.

Step 6 — Test Another LED Bulb

Use a known high-quality LED lamp.

Step 7 — Test Another Power Supply

For 12 V cameras, use a separate known-good adapter.

Step 8 — Check Cabling

Inspect:

• BNC connectors
• RJ45 connectors
• DC connectors
• UTP pairs
• Coaxial shielding
• Cable joints

Step 9 — Check Cable Route

Look for long parallel runs near AC cables.

Step 10 — Check Grounding

Especially for analog systems.

Step 11 — Check the DVR/NVR

Connect the camera to another channel if appropriate.

Step 12 — Test Another Camera

If another camera works correctly at the same location, compare camera settings and sensor characteristics.

32. Recommended Starting Configuration for CCTV Under LED Lighting

For a typical installation in India, a reasonable troubleshooting starting point is:

Power Frequency / Anti-Flicker: 50 Hz

Exposure: Auto initially

Shutter: Avoid unnecessarily fast fixed shutter settings

WDR: Enable only where high dynamic range is actually needed

HLC: Use when strong highlights are a problem

BLC: Use when subjects are backlit

Then fine-tune according to the actual environment.

There is no single shutter value that is perfect for every LED lamp because different LED drivers use different switching and modulation methods.

33. Why Changing from 50 Hz to 60 Hz May Sometimes Appear to Help

Technicians sometimes find that changing anti-flicker settings unexpectedly improves a particular installation.

This can occur because the LED driver itself may be operating with complex electronic switching rather than producing simple mains-related modulation.

However, in a 50 Hz country such as India, 50 Hz remains the logical starting point.

If unusual behavior continues, the actual lighting equipment should also be investigated.

34. Why Only One Camera May Be Affected

Suppose eight CCTV cameras are installed but only Camera 4 shows flickering.

Possible reasons include:

• Camera 4 faces the LED directly
• Different exposure settings
• Different camera model
• Different sensor
• Different firmware
• Different cable route
• Different power supply path
• Poor connector
• Greater cable length
• Nearby LED driver
• Grounding problem

Therefore, “other cameras are fine” does not automatically prove that the LED is innocent.

35. Why the Problem May Appear Only at Night

During daytime, the camera receives significant ambient light.

At night, the LED may become the dominant illumination source.

The camera may also automatically change:

• Exposure
• Gain
• Shutter
• IR mode
• Day/night filter

Consequently, LED flicker or banding may become much more obvious at night.

36. AGC Can Amplify the Problem

AGC = Automatic Gain Control

When a scene is dark, the camera increases electronic gain.

Unfortunately, gain amplifies both the useful video signal and noise.

Therefore, at night you may see more:

• Grain
• Electrical noise
• Banding
• Flicker

Improving illumination can sometimes provide better results than simply increasing gain.

37. Why a Camera May Show Strange Colors Under LED Lighting

LEDs do not necessarily produce a smooth spectral output like daylight.

Different LEDs have different spectral characteristics.

The camera's automatic white balance may therefore become confused.

Possible symptoms:

• Blue-looking faces
• Green tint
• Purple tint
• Yellow image
• Colors changing as people move

Try:

• Auto white balance
• Indoor white balance
• Manual white balance
• Better-quality high-CRI lighting

38. LED Color Quality and CCTV

CRI = Color Rendering Index

Higher-quality lighting generally reproduces colors more naturally.

For CCTV applications where color identification matters — clothing, vehicles, products, documents — lighting quality should be considered as part of CCTV design.

High brightness alone does not guarantee good surveillance lighting.

39. Security Installers Should Test Lighting Before Final Installation

During CCTV commissioning, test cameras with:

• Daylight
• Night lighting
• LED lights ON
• LED lights OFF
• Emergency lights
• Signboards
• TV screens
• Monitors
• Vehicle headlights where relevant

A camera that looks excellent at noon may behave very differently at night.

40. Recommended CCTV Installation Approach

For a professional installation:

Lighting → Camera → Lens → Exposure → Cabling → Power → Network → Recorder → Display

should be treated as one complete system.

Image quality depends on all of these components.

Simply purchasing a higher-megapixel camera cannot compensate for badly designed lighting or electrical interference.

Quick Symptom Diagnosis Table

Symptom	Likely Cause	First Check
Moving dark horizontal bands	LED flicker/shutter mismatch	Anti-flicker 50 Hz
Entire image brightness pulsing	LED driver ripple/PWM	Test different LED
Lines remain with lens covered	Electrical interference	Power/ground/cabling
Lines disappear with lens covered	Optical flicker	Exposure/LED driver
TV has moving black bars	Refresh/shutter mismatch	Camera exposure
LED signboard partly disappears	Display scanning/PWM	Shutter/exposure
White glare around LED	Overexposure	Exposure/HLC
Person dark behind LED	Backlighting	WDR/BLC
Night image white/foggy	IR reflection	IR placement
Camera restarts when IR starts	Insufficient power/PoE	Power budget
Slowly rolling analog CCTV lines	Ground loop	Grounding
Random noise near LED driver	EMI/RFI	Cable routing
Strange color under LED	White balance/spectrum	AWB/lighting
Flicker increases with fast shutter	LED modulation	Reduce shutter speed
Problem only when dimmed	PWM/dimmer	Test 100% brightness

FAQ

1. Why does my CCTV camera flicker when LED lights are switched on?

The LED driver may produce rapidly varying light output. The camera shutter and sensor can capture this modulation as flickering or bands.

2. Why can I not see the LED flickering with my eyes?

The modulation may occur fast enough that your visual system perceives it as continuous light, while the camera captures individual portions of the cycle.

3. What anti-flicker setting should I use in India?

50 Hz is normally the correct starting setting because India's mains electricity frequency is 50 Hz.

4. Does 50 Hz mean that CCTV should record at 50 FPS?

No. Electrical frequency and video frame rate are different parameters.

5. Why are horizontal black lines moving across CCTV?

Possible causes include LED flicker, shutter mismatch, electrical interference, power supply noise, or a ground loop.

6. How can I determine whether LED light itself or electrical noise is causing the problem?

Cover the camera lens while keeping the LED powered on. If the problem disappears, optical flicker is likely. If it remains, investigate electrical interference.

7. Can cheap LED bulbs affect CCTV?

Yes. Poor-quality LED drivers may have higher ripple and inadequate EMI filtering.

8. Can expensive LED lights also flicker on camera?

Yes. PWM or other control methods can cause camera-visible modulation even in otherwise good lighting products.

9. Why does my TV show black moving lines on CCTV?

The television refresh rate and camera exposure/readout are not synchronized.

10. Is the TV defective?

Usually not. If the TV looks normal directly but only shows bands through a camera, it may simply be a timing/refresh phenomenon.

11. Can LED signboards cause CCTV flickering?

Yes. LED displays commonly use high-speed scanning and PWM.

12. Can changing shutter speed solve the problem?

Often it can reduce the problem substantially. The correct value depends on the lighting system and camera.

13. Why does a fast shutter sometimes make LED flicker worse?

A fast shutter captures a shorter portion of the LED's brightness cycle rather than averaging it.

14. Can WDR remove LED flicker?

Not necessarily. WDR handles high-contrast scenes; anti-flicker and exposure settings address flickering.

15. What is the difference between WDR and BLC?

WDR handles scenes containing both bright and dark regions. BLC mainly increases exposure for a dark subject against a bright background.

16. What is HLC?

Highlight Compensation attempts to reduce the effect of extremely bright sources such as headlights.

17. Can CCTV power supply cause moving lines?

Yes. A faulty or noisy SMPS can introduce electrical noise into a CCTV system.

18. Can a PoE switch cause camera problems?

Yes. Poor PoE delivery, insufficient power budget, bad cables, or defective hardware can cause instability and camera resets.

19. Can LED drivers generate EMI?

Yes. Switching LED drivers can generate electromagnetic and radio-frequency noise if poorly designed or installed.

20. Should CCTV cable and electrical cable run together?

Long parallel runs should generally be avoided where practical, especially around noisy electrical equipment.

21. Why is the CCTV image worse when an LED dimmer is used?

The dimmer may use PWM or phase-cut control that increases light modulation or electrical noise.

22. Why is only one CCTV camera affected?

Its viewing angle, exposure, cable route, power supply, sensor, or proximity to the LED driver may be different.

23. Why does the problem occur only at night?

The LED becomes the primary illumination source, while the camera also changes gain, exposure, and day/night settings.

24. Can infrared LEDs cause flicker?

IR systems can have their own modulation issues, but common night problems also include IR reflection and overexposure.

25. Why does CCTV behind glass become white at night?

The camera's IR LEDs can reflect from the glass directly into the lens.

26. Can LED lighting change CCTV colors?

Yes. LED spectral characteristics and automatic white balance can cause color shifts.

27. Does higher megapixel resolution solve LED flicker?

No. Resolution does not correct a timing mismatch between the lighting and camera exposure.

28. Should I replace the camera or LED first?

First test anti-flicker and exposure settings. Then test a known-good LED lamp and camera power source before replacing equipment.

29. Can ground loops cause rolling lines?

Yes, particularly in analog CCTV systems.

30. What is the best permanent solution?

Identify whether the cause is optical flicker, electrical interference, grounding, cabling, or display-refresh mismatch, and correct the actual cause rather than randomly replacing components.

Conclusion

When LED lighting causes strange effects on CCTV, the problem should not immediately be blamed on the camera.

Modern CCTV cameras, LED lamps, LED TVs, monitors, and digital displays all operate using high-speed electronic timing.

The visible CCTV image is influenced by the interaction of:

AC frequency + LED driver + PWM + display refresh rate + camera shutter + exposure time + sensor readout + frame rate + power quality + grounding + cabling

In India, checking the camera's 50 Hz anti-flicker setting is a sensible first step.

However, if the disturbance remains even when the camera lens is completely covered, technicians should investigate electrical causes such as the camera power supply, LED driver EMI, grounding, cable routing, connectors, and ground loops.

A good CCTV installation is therefore not just a camera-and-recorder installation. Lighting and electrical design are part of the surveillance system itself.

 

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