A LAN (Local Area Network) is a data network within a single building or site, connecting computers, phones, televisions, cameras and building services to one another and to the internet. It may be wired (ethernet over twisted-pair cable), wireless (Wi-Fi) or — in practice almost always — a combination of the two.
Why is this in a building knowledge base?
Because the cabling has to be designed in during construction. Cables and conduits go in while walls and floors are open. Retrofitting means chasing, routing, plastering and decorating — or visible trunking along the skirting. The data network therefore belongs on the services drawing alongside the electrics and the plumbing.
Components
- Patch cabinet — the central point, often in or beside the consumer unit or in a plant space.
- Cabling — category 6 or 6A twisted pair for new installations.
- Outlets with RJ45 connectors at the points of use.
- Switch, router and access points for distribution and the wireless part.
Rules of thumb
- Always run cable to the fixed positions. Living room (television and media unit), study, and above all to wherever the Wi-Fi access points will sit — centrally in the building, preferably at or in the ceiling.
- Maximum length. A copper ethernet link may be at most 100 m in total under the cabling standard ISO/IEC 11801, including the patch cords at both ends. In a large house or across to an outbuilding, check the run or use fibre.
- Keep clear of mains cable. On long parallel runs, distance (in the order of 20 to 30 cm) reduces interference; where you must cross, cross at right angles.
- Lay spare conduit. A 19 mm flexible conduit from the patch cabinet to each floor costs very little at first-fix stage and saves chasing later.
- Wi-Fi obstacles. Thick concrete floors, steel studs in timber frame construction and insulation foils with an aluminium vapour-control layer weaken a Wi-Fi signal considerably. Do not count on a single access point in the meter cupboard in such a building.
- Ventilate the cabinet. A switch and a router generate heat; a sealed cabinet in a small cupboard runs hot.
Related terms
- Home automation
- Building services
- Electrical wiring
- Digitalisation
- Connected load
Want to know more about building terms? Take a look at our knowledge base on fredsdiyplans.com.