Tony Jones
Tony Jones - Sales – 2M CCTV
877-926-2288 x 6025
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.
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).
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.
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
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.
it was quite informative for the people who who are very keen about the installed cameras and there video quality while recording ! these all features re mainly acknowledged by the security surveillance team but it will be very beneficial if you install by yourself!
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.
Great Information thanks………………
You get a lot of respect from me for writing these helpful articels.
Yes, from experience using a CCTV GL isolator solved the problems 95% of the times.