Analogue connections from the camera to require a balanced two core cable to carry the video signal.
Analogue CCTV cameras and Digital Video Recorders (DVRs) are fitted with female BNC connectors and are traditionally connected using balanced (75Ω) coaxial cable. This is known in the trade as RG59 and is available in several variants as described below. Instead of using balanced cable it is possible to use unbalanced cable such as twisted pair (CAT5) or multi-core alarm cable with the addition of balancing units (baluns) at each end of the cable. There are advantages to using unbalanced cable as described below.
Using RG59 and its Variants
Balanced Co-axial cable (RG59) is a simple and easy way to connect cameras to a DVR. A single cable is required for each camera. RG59 is available in several variants as in the table below.
Standard balanced (75Ω) coaxial cable, round, diameter 6mm. Fixed with 6mm round cable clips. Uses standard BNC connectors – crimp or twist-on. Cables can be supplied readymade with the BNC plugs fitted.
RG59 + 2, Shotgun, Siamese
Standard RG59 with a smaller 2-core round power cable attached. Overall dimensions 12mm wide by 6mm deep. Fixed with 12mm x 6mm flat cable clips. Uses standard BNC connectors – crimp or twist-on for the video signal. Power can be supplied from a terminal type Power Supply Unit (PSU) or through an adaptor.
Smaller, round, diameter 4mm. Uses Mini BNC crimp-on connector.
Mini RG59 + 2
Similar to Mini RG59 but with 2 power cores incorporated in a round, 5mm diameter cable. Cables can be supplied readymade with the BNC and power plugs fitted.
Although RG59 is relatively easy to use – it simply needs plugging in to camera and DVR – it is not the easiest to physically install. The problem arises due to the relatively large BNC termination which requires access holes of at least 16mm for it to pass through. This can be alleviated by attaching the BNC plug after passing it through a wall. This still leaves the problem of getting power to the camera. If standard RG59 cable is used and the camera is powered locally then either a larger hole will have to be made or a separate hole for the power supply drilled. For RG59 + 2, either a large hole or two adjacent holes will have to be drilled. Fitting cameras internally is less of a problem but can be difficult on outside walls where the preferred method is for the cable to pass through the wall directly behind the camera or at least very close to it. A better solution is to use Mini RG59 or Mini RG59 + 2. Again, it is better to attach the BNC plug after the cable is passed through the wall. Twist-on BNC plugs are not available for Mini RG59, so crimp-on BNC connectors will have to be used. Also note that when installing cameras outside it is easier to fit a BNC plug to one end of the cable and to pass the un-terminated end of the cable from the outside to the inside. The other BNC can then be fitted in comfort at the DVR.
There are three main BNC connectors for terminating RG59.
Standard BNC Crimp
Standard BNC Twist-on
Mini BNC Crimp
Applying Camera Power
All CCTV cameras require electrical power. This is usually 12v for non-PTZ cameras and usually 24v for PTZ cameras. Power to the cameras can be supplied locally, or from a central point - usually near the DVR. Locally powered cameras can use simple 1 Amp in-line power supplies. These are usually fitted with a pre-fiitted mini-jack power connector designed to connect to the mini-jack on the camera. If you are fitting the camara externally you may want to cut off the mini-jack plug and feed the wire through the wall. The cable can then be reconnected to a mini-jack using an adaptor - Shown below.
Using Twisted Pair (CAT5) or Alarm cable
Most of the above problems can be alleviated by using unbalanced cable such as CAT5. Except over short distances (5 metres), baluns need to be used to use CAT5 to connect cameras to a DVR. A balun needs to be fitted at both the camera end and at the DVR end of the cable. CAT5 cable comprises 4 x twisted pairs and as such the cable can carry signals from up to 4 cameras or from 3 cameras and the power supply to the cameras. Junction boxes will need to be used to break-out the video signals and power form the CAT5.
CAT5 cable is available in external grade and is 5mm in diameter.
Baluns are small in-line units which are used to balance the attenuation of the cable to and from cameras connected to a DVR. When using unbalanced cable such as CAT5 a balun is required at each end. In general baluns are not required for short unbalanced cable runs. There are two types of balun used in CCTV installations – passive baluns and active baluns. Passive baluns are capable of producing excellent video signals at up to around 300 metres, greater than this distance will require the use of active baluns. When using active baluns, which will require power, it is usual to use just one active balun at the DVR end and a passive balun at the camera.
Baluns are available in various designs and are always fitted with a BNC male connector at the input end. The BNC connector may be part of the balun body or may be tailed in order to provide more room at the DVR connections. Baluns at the DV may also be part of a multiple block. The output can be via screw terminals or RJ45. There are also versions which have data (for PTZ cameras) and audio connections. Typical passive baluns are shown below.
Physical Wiring Schemes
- A few practical examples of wiring cameras to a DVR are given below. A few general rules should be adhered to when installing the wiring.
- Always use good quality cable, use solid copper cable and not CCA (copper coated aluminium), and if the cable is exposed externally, then use external grade cable.
- Aim to reduce the amount of visible cable to the camera. Use junction boxes or camera cable management boxes.
- Ensure that all joints are properly made – do not tape wires together. For external joints, enclose them in weatherproof junction boxes. If you have to run an external cable along a wall and into a camera, ensure that the cable enters the camera at the bottom and that the cable has a drip loop before it enters the camera.
- Avoid running cable around sharp corners – the strain on the cable will cause it to fail prematurely.
- Ensure that all cable entry holes are fitted with a weatherproof grommet or are manually sealed using silicon sealant.
- Avoid running cables in parallel with mains cables – you will get induced emf signals.
- Secure the cable at regular intervals using correctly sized cable clips.
- Avoid routing the cable where it may be damaged by people walking past it for example.
As mentioned above, using RG59 and its variants can be demanding, especially when fitting cameras externally. The following examples may help in wiring efficiently.
Example 1 – using Standard or Mini RG59 and a local Power Supply
We need to connect a camera on an external wall at a height of 4 metres to a DVR located at ground floor level. The cable has to be routed upward from the DVR, through the ceiling and then through the exterior wall.
- Drill the required holes in the ceiling and exterior wall (and any other obstructions such as shelves) along the proposed cable route. Note that because we are powering the camera locally, we need to either drill an additional hole through the exterior wall or make the hole in the external wall large enough to accommodate both the RG59 and the Power cable. If the power cable is fitted with a plug, this can be cut off and the connection re-made on the outside of the wall using a power-plug connector.
- Measure the length of RG59 cable required for the proposed route and cut the cable to the required length.
- Fit a standard BNC connector to one end of the cable – crimp or twist-on.
- Feed the un-terminated end of the cable through the wall from the outside to the inside and through any other pre-drilled holes back to the DVR.
- Feed the power cable through the external wall.
- Connect the BNC and power cables to the camera either through a junction box or to the rear of the camera. How this is done depends on the camera type and how much room is available to make the connections.
- Fasten the cable to the external wall if possible to prevent the cable being pulled from the inside.
- Fit the camera to the exterior wall and from the inside pull any spare cable gently to the inside. Fasten the cables to the interior wall.
- Work back to the DVR and fix the cable at regular intervals.
- Cut the cable to its final required length. If possible leave a little spare cable length.
- Fit a BNC connector to the end of the cable.
- Plug the camera into the DVR and test the camera.
Example 2 – Using Standard RG59 + 2 or Mini RG59 + 2 with power supplied remotely
Using the same route as in Example 1, but with the camera’s power supplied from a central PSU near the DVR. The procedure is similar to Example 1 but the hole for the standard RG59 + 2 will either need to be larger or the cable can be split and two holes drilled through the external wall.
Using CAT5 Cable
One of the great advantages in using CAT5 (or other multi-core cables) is the ability to carry multiple signals on a single cable. CAT 5 has 8 cores available which can be used to carry the video from 4 cameras, or the video for 3 cameras and the power supply, or the video, power and audio from a single camera, or the video, power and data from a PTZ camera. Note that video signals will have to have baluns fitted at both ends of the cable.