A User's Guide to Digital Video Surveillance


Many cameras today are 12-volt. The reason we mention this is cameras of the last generation were primarily 24-volt. So if you plug a 12-volt camera into an existing line that is 24-volt, you may very well destroy the camera. Many of the better cameras today are dual voltage and can support both.

For the most part CCTV cameras can be purchased in 3 voltages: 120VAC, 24VAC and 12 VDC.

120VAC is not very common as it has some drawbacks the main being the requirement of having an outlet within 6 feet of where the camera is to be installed.

24VAC historically has been the professional's choice although more and more we see 12 VDC being used extensively. In fact, the majority of cameras available in the market today are 12 VDC. Longer distances though can be run for powering 24VAC wires. 12 VDC can also be used but distances are somewhat shorter than 24VAC due to voltage drop. You can view a voltage drop calculator in our “How it Works” section” or by clicking on the link.  Distance only becomes an issue when running longer than several hundred feet. The convenience of 24VAC and 12 VDC is you can run the cables from the respective camera positions to a central point into a single power panel.

The camera power supply is most commonly connected using low voltage 18 or 20 gauge wire. The popular method for running video from the camera to the monitor or recording device is across an RG-59 or RG-6 coaxial cable. For convenience, “Siamese” cable can be purchased which houses the video and power under a single jacketed cable. Alternatively, a new method of cabling is running the video across Cat-5 computer network cable. Cabling is discussed further in our “How it Works” section of the website and elsewhere in this tutorial.

Each and every camera requires power. There are a few ways to power a camera.

Power Supply

1. A small power pack can be connected to the camera and plugged into a local wall outlet, typically within a 6’ range.  This in many cases is not possible as the cameras are located where there is no wall outlet.

Power Panel

2. Electrical wire can be run from each camera back to a central location and all the electrical wires are terminated in a power panel.

Messy Power Strip

3 .Electrical wire can be run from each camera back to a central location and all the electrical wires can each be attached to individual transformers, which can be plugged into a power strip and then into the wall. This method is not recommended as it usually is not very neat.

Siamese Cable

4. There is a type of cable known as “Siamese” cable, which houses a cable for video and an electrical wire for power, all in one single jacket. This way you only have to run a single cable from the camera back to the central location where the DVR and power are to be terminated.

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