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1

Cabling infrastructure


Poorly or incorrectly installed network cabling can cause numerous problems in your computer network.

However small it may appear, a problem with network cabling can have a catastrophic effect on the operation of the network. Even a small kink in a cable can cause a camera to respond intermittently, and a poorly crimped connector may prevent Power over Ethernet (PoE) from functioning properly.

If there is existing cabling in an installation, an adapter can be used: the AXIS T8640 Ethernet over Coax Adaptor PoE+ is an ideal choice for installation of network cameras where coax cables are already present and may be very long or inaccessible. AXIS T8640 Ethernet over coax Adaptor PoE+ enables IP-communication over existing coax video cabling and converts an analog system to digital. With this adapter, the cabling can be 500 meters instead of 100 meters.

Considerations when cabling


Use the correct wiring standards


There are two wiring standards for network cabling: T568a and T568b. DO NOT COMBINE T568a and T568b on the same cable.


Use high-quality CAT 5e or CAT 6 cabling


Cables are categorized according to the data rates that they can transmit effectively. The specifications also describe the material, the connectors and the number of times each pair is twisted per meter. The most widely-installed category is CAT 5e. Ensure that the cabling in your installation fulfills the required Category (Cat).

  • Cat 3 (no longer used) with 16 MHz bandwidth
  • Cat 5e with 100 MHz bandwidth
  • Cat 6 up to 250 MHz
  • Cat 6A up to 500 MHz
  • Cat 7 up to 600 MHZ
  • Cat 7A with a frequency range through 1000 MHz

Video files are generally very large data files, and need to be moved around the network as quickly as possible. In general, it is possible to use good-quality Cat 5 cabling for gigabit networks; it is recommended to utilize Cat 5e or Cat 6 cabling for gigabit connectivity, even if your existing network switches and routers support only 100 Mbps. This will ensure that the cabling infrastructure is in place when the gigabit upgrade occurs. The rest of the points apply equally to 1 Gbps and 100 Mbps connections – each can be affected by poor cabling and incorrect connections.


Have good cable runs


Ensure that your cabling meets the requirements of your equipment. The distance between a transmitter and a receiver cannot be greater than 100 m (325 ft) in total. If installing sockets, remember to take into account the distance between the socket and the computer. A good rule of thumb is 90 meters for horizontal runs, and ten meters for the patch cabling. It is also important to be aware that the whole length of cable and connectors is of the same type, such as STP.

Do NOT run cabling next to electrical mains cabling (because of the potential for interference), or suspend network cabling from ceiling tiles (this may violate building codes and fire regulations).

Axis network products are intended to be used with Shielded Twisted Pair (STP) cables in Europe due to CE-marking requirements and are EMC approved with STP cables. This requirement is also valid for several other countries such as Australia/New Zealand, Canada, Korea and Japan. The use of STP cables is especially important to maintain a high degree of immunity to RF (Radio Frequency), electrical and magnetic disturbances as well as provide the lowest possible degree of radiated and conducted Radio Frequency emission.

It is also mandatory to use an STP cable where the camera is used outdoors, or where the network cable is routed outdoors. STP cables also lower the effects of close situated power relays, motor inverters and electrical cables that are run in parallel close to network cables. Shielded Twisted Pair (STP) cabling needs to be grounded. This is normally accomplished since the switch or POE adapter is connected to an earthed mains socket. For more information about STP versus UTP, go to Shielded or unshielded network cables

However, there are Axis network products that have been tested to fulfill EMC requirements in the USA for use indoors with unshielded cables, UTP. The tradeoff in using UTP cables is a higher level of emitted Radio Frequency emission and higher susceptibility to radio frequency immunity. The electrical environment shall be considered when deciding which type of Twisted Pair cable is to be used.

Since network cabling typically uses solid wire, cabling should not be twisted or bent into a tight radius (not less than 4 times the diameter of the cable). Do not use metal staples to secure cable runs, nor tightly adjusted cable wraps. Avoid a daisy chain network topology.


Use the correct connectors


Network connections use RJ45 connectors designed for either stranded or solid cable, but usually not both. Ensure that you use the correct crimping tool for the specific type of connector. Please certify that the type of RJ45 connectors is coordinated with the type of cable, STP or UTP, used.


Keep the pairs together and wire correctly


A network cable consists of four pairs of twisted wires, and these are color coded (orange, green, blue and brown). The cable specification has been designed for high-speed data transfer and very little cross-talk. It is very important that no more than about 6 mm of the cable is untwisted at either end; otherwise, problems such as ‘near end cross-talk’ can arise, which will have a detrimental impact on your network. It is essential that you wire the plug correctly and not just from pins 1 through 8 at both ends.


Environmental conditions


Environmental considerations, for example whether the camera will be installed indoors or outdoors, determine the cabling and connectors to use.

Depending on the environment, the camera should be installed with the adequate housing to provide the correct level of protection. If the camera is exposed to acids, severe weather conditions, or extreme heat or cold, the camera needs a housing that withstands this kind of environment. For more information on Environmental issues, see Challenge 5, Environmental Considerations.


Certify the installation


In twisted-pair copper wire networks, copper cable certification is achieved through a thorough series of tests in accordance with standards set by the Telecommunications Industry Association (TIA) or the International Organization for Standardization (ISO). These tests are done using a certification testing tool, which provide "Pass" or "Fail" information.



Figure 1. A well-installed, well-structured cable enclosure using color-coded cabling makes for a much more professional appearance and also demonstrates adherence to specific standards.






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