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Video Ground Loop Interference for CCTV

Tony Jones - Sales - 2M CCTV

Tony Jones

Tony Jones - Sales – 2M CCTV

877-926-2288 x 6025

Video Ground Loop Interference

Video Ground Loop Interference

Joe calls from the county jail, he just finished installing 16 cameras for the jail and now that he has all the cameras up on the monitor there are small lines running through the screen on each camera.  His first thought is that there is defective equipment.  Either the CCTV cameras or the DVR are bad.  Neither is bad, the culprit here is video ground loop interference.

 

Ground Loop

I will spare you the science of a ground loop (which looks like this)…

Just know that they cause horizontal lines in the video monitor.

 

This can be caused by many different factors and tracing the issue can be a pain.  One cause is running your cable over a high power source. This can also be caused by load unbalance when high power is shut on and off.  To avoid this, make sure to run camera wires away from power lines (a minimum of 12 inches) if possible and especially not directly on top of them.

If you are using 24vac power transformer and you have this problem you can reverse the wire on the power supply to get the bad signal to go away.  This is an old trick that some of the Veteran CCTV installers use (let us know if you’re looking to become a CCTV installer).

Keep Camera Cable Away From Power Lines

 

Another issue with ground loops are metal buildings.  There are times when customers mount cameras to the side of a metal building and the entire building is one large conductor.  Often I tell them to put a piece of wood between the camera and the wall and that will fix the interference caused by video ground loops.

Piece of Wood Between Camera and Wall

 

Lastly there are video ground loop isolators (or “isolation transformers”).  They are small pieces that are run in the line between the camera and DVR.  Most of the time adding this piece will solve any ground loop interference in the video feed.  I sold some to Joe and they worked great!

2MCCTV sells ground loop isolators for only $16.

Ground Loop Isolator

Ground Loop Isolator

22 thoughts on “Video Ground Loop Interference for CCTV

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  2. I used Pelco 16CH Switcher 4 camers are not work correctly on display there screen are moving… like its hanging.else other 12 cameras are display fine on same device.

  3. I have a 16 channel lorex eco system with 2 ptz cams and 14 (720 tvl cams) that work great. Cables run from dvr to each camera which are Siamese bnc and power cables. All my cams work great except for 4 cameras. My issue is that 4 stationary cams have interference and only those 4 cams show it on the screen which looks like faint thick horizontal lines on the view that is random areas not scrolling. I have tested the cams with for sure working cams, switch ports on dvr, and good to go cables, however the cable runs for these four cameras are separate routes than all other cameras that work just fine except the 2 PTZ cams (which were routed the same as the 4 issue prone cams) the PTZ cams work fine without distortion but I have narrowed down the biggest issue were the video feed go completely black (no video at all) DVR view four only these channels are black. When the video goes blank there is still power to the cams and working (tested by covering IR sensor and working) the issue is when outdoor sign comes on and triggers video to cut all the way out. Will the use of BNC box you recommend help with this issue and if yes where should the box be connected if 2 set of runs are used (ie. 75 foot run cable from to dvr to coupler with addition 75 foot run to camera) to each camera?

    • I have eight still cameras and four, always the same four cameras I have a problem with. Sometimes one camera will flicker and then it goes out saying video loss. Then after it will come back on. One camera of the four goes out at one time, not all four. I never have a problem with the other four and they are all connected to a eight channel dvr. Can you tell me what the problem might be?

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  5. The Isolation Transformers are in high demand to render safety to the electronic devices at your home. We can save upto a large extent in the electricity bill with the aid ofvoltage stabilizers.

  6. Related to the article, if the cameras are plugged to the 16ch dvr one at a time, the video is clear. But when i start putting them together waves appear on some cameras. Any thoughts on this?

    • Mac…

      I seem to have the same problem with my system. Ive tried a switching power supply with adjustable voltage because I suspected voltage drop, and it did not fix the problem. Were you able to resolve your issue, and if so may I ask how?

  7. Travis, your answer on PTZ cams was extremely helpful. Im trying to troubleshoot a single camera, and after your comment, I rechecked my monitors and noted that half the PTZ cams had the same problem. Specifically; the cameras I used a secondary controller on. Within seconds of unplugging this suspect controller, the interference patterns vanished. If only all tech support was that easy!!

  8. I’ve configured 4 CCTV cameras in outdoor housings that contain heaters & fans. When the the heater turns on I get the rolling bars. At all other times they work fine. Will a ground loop isolator reslove this? Is there a better way to fix the problem rather than cover it up?

    Tks, Jeff…

    • When it comes to PTZ’s here is the checklist for making sure the connection should work:

      1.) Cables are connected to the correct terminals. (positive to positive, negative to negative)
      2.) Make sure the address of the camera matches the address of the controller.
      3.) Make sure the protocol and baud rate of the camera match the controller.

      If it is still not working then you will need to verify that the controller is functional. If all these steps have been completed you may need to call tech support for further troubleshooting tips.

      -Travis

  9. I have one camera on a 6 camera system scrolling horizontal lines. It just started today and lasted for about 6 hours, then stopped. They are all DC 12V Cameras connected to the same power supply. Could the power supply be going bad. We used a diffrent power supply on this system than we normally do and we suspected problems from the beginning. It has 8 different connections with their own fuses.

    Thanks in advance.

  10. Hi,

    I have recently plugged 12 cctv cameras to 16 Channel DVR, now the problem is with 2 cameras. When i switch to channel 1 in full screen mode, i can see in the background the live of channel 4, and in channel 4 in the background, i can see the live of channel 1, rest all the channels are perfect and quality is good. I have checked these two cameras on the other DVR, it has no problem. I tried to plug these two cameras into differnt channels as i have 4 channel still to be occupied, now they are interfering into the channels. What could be causing this interference.

    Anticipating your quick help on this.

  11. I have a single camera, wireless cctv system in my house. It has worked with no problems for the last 2 years. The other day I turned it on and I have the ground loop lines on the monitor. What would cause it to work fine for years then have this problem? Wouldn’t one know instantly they had a ground loop problem the moment you use the system for the first time?

    • Ground loops are a problem with interference in physical cable. What you are talking about seems more like an interference within the wireless signal. The only thing I can think of is there must be a new variable causing the interference. Try moving the camera to test if you can get a clean feed from it.

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