Monitor showing ground loop interfence

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Humbars = Interference

Many CCTV installers have seen the classic symptoms of the rolling humbar or the tearing picture but don’t always know the cause of the problem and the solutions to cure it. Humbars or groundloops occur when there is more than one “ground” or “earth” between two pieces of equipment. Loops form and the result is interference on CCTV images such as a rolling grey bar.

Although using a good quality power supply should help prevent this from happening, in complicated systems where a range of equipment is used it is not always easy to eradicate.

How can it be fixed?

Simply plug in a HumBloc & stop interference in its tracks

The low-cost HumBloc is a groundloop isolator that simply terminates ground loop currents in a cable and blocks the hum and interference carried in the ground loop.

The Humbloc should be fitted between the camera and the input of CCTV equipment such as a DVR that it is connected to, ideally at the rear of the DVR directly into its video input(s).

Thanks to Quad Technology the HumBloc is compatible with HD-TVI, HD-CVI, AHD and Analogue technology. It is very easy and quick to fit as it has BNC connections.

4 way extension leads


  • Input: BNC Socket
  • Output: BNC Plug
  • Capability: HD-TVI, HD-CVI, AHD & Analogue
  • 43 x 28x 21mm (exc cables)
  • Cable length: 200m pigtails
  • Frequency: 150MHz max

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