To determine the Network Cables best suited for a particular security video system, a company will need to consider a few aspects to help decide whether to use unshielded twisted pair (UTP), coax or fiber cable for transmission.
If distances are shorter than 100m, coax cable is probably the best option. Between 100 and 2500m, Unshielded Twisted Pair (UTP) is often the best choice. If the runs are more than 2500m, your best bet is on fiber.
Other conditions that may indicate UTP wire include runs between buildings and floors, noisy environments, existing UTP wire, or the need for plenum cable or conduit. For companies using cameras with built-in UTP transmitters, pan, tilt and zoom (PTZ) cameras, or a DVR that is sensitive to attenuated video, UTP may be the transmission mode of choice.
At the head end, the blue Cat5 wires are punched down to the 110 blocks and redirected via single pair cross-connect wire to the 48 multi-channel receiver hubs. The control wires are broken out into the orange single pair cross-connect wire that continues on to the back of the multiplexers. The incoming bundles hold enough wire pairs to run over 1600 cameras with PTZ control.
This is because UTP lets the end user share cable to reduce both labor and cable costs. Multiple pairs in a single cable can be used for video signals with control or video signals with 24VAC power. The end user can even share video with ringing telephones or data lines – all noise-free.
With UTP, systems also can be designed to maximize cable usage. New on the market, and available from several different cable manufacturers, is a UTP composite cable, also known as a “Siamese” UTP cable.
At short distances, however, the cost of the UTP transceivers becomes a factor. Typically, coax costs less for small camera counts on non-plenum wire that is less than 100m in length. In most other cases, UTP is more economical.
End users with a plenum environment also can benefit from UTP, as the cable is jacketed with two types of material: PVC, a low-grade plastic, and plenum, which is fire-rated Teflon. PVC coax costs up to 50 percent less than plenum coax, which is required by most fire codes for ceiling and in-wall wiring in commercial buildings.
As the number of coax cables needed increases, each extra coax adds its own plenum jacket, while UTP can have up to 100 UTP pairs inside a single plenum jacket. Savings on the wire and the labor to pull it really add up as the number of required pairs increase.