USB webcams receive their power and transmit their images along the same USB lead. A USB lead combines both data and power into one cable, with power for the web-camera being supplied by the connected computer or USB hub. This means that in general, USB web-cameras have no need for a separate power brick.

USB leads terminated in either A (top) or B style plugs, carry both data and power, however, they can only trail to distance of five meters (15 feet) away from a computer or USB hub. This constraint afflicts all USB devices including external disc drives and printers. The ideal location for a weather web-camera will often exceed this distance. So called USB extenders can increase this range in multiples of five meters, but they become costly and are far less reliable than a long-range network cable. In fact, many long-range USB extenders use network cable anyway.

Ethernet is the name used to describe the most common form of computer network. Even through USB is sometimes used to build networks, USB is not a sound alternative to Ethernet. Ethernet is designed to be robust, flexible and scalable.

Computer networks are built around devices called switches, hubs and routers. All of these devices act as some form of a central node into which are plugged computers, printers and other switches, hubs and routers. Collectively, a group of computers networked together is called a Local Area Network or LAN.

A LAN could be made up of many hundreds of PC's in an office building or, be just a single home PC plugged into a cable modem; the cable modem itself being a router. Many LAN's converge together to form a Wide Area Network, or WAN. Generically, all WANs added together form The Internet.

All devices connected to an Ethernet network communicate with each other using internet protocols. An IP Camera uses internet protocols, which is how it can communicate across the internet without requiring an interviening computer. And hence the name, Internet Protocol camera. Pictured, an IP web-camera connects to the world over a local area Ethernet network via the RJ45 socket at it's rear. This network is then probably accessible across the Internet. In the home, there needs to be a corresponding and spare network port on the cable modem to connect the web-camera to. Too often, both network and power cables shipped with an IP web-camera are far too short to be of any practical use. Custom leads will need to be fabricated.

The cable used on an Ethernet network is described as UTP cable, which stands for unshielded twisted pair. Inside, the cable has eight cable cores arranged as four twisted pairs, but unlike with audio and video cables, there is no foil shielding around the inner cores. It is the twisting alone that provides a degree of isolation from interference from outside the cable and, allows the cable to carry data at very high rates up to a distance of 100 meters (300 feet). Often, the cable is named by its specification schedule of Category-5 (think of the worse hurricane level), which is abbreviated to Cat-5 or Cat-5E. Network cable is terminated with an RJ45 module (wall socket) or, an RJ45 plug. Cat-6 cable is very similar, but will allow even faster data transmission rates.

Each length of Cat-5 cable can run to 100 meters (300 feet)

IP web-cameras that use Ethernet network cable can be up to 100 meters (300 feet) away from a DSL router, which gives significant flexibility when positioning a weather web-camera. In practical terms, both network and power supplies must be considered. Although network cables can be over 100 meters long, the power cables fitted to the power bricks supplied with an IP camera are often an inconvenient meter in length; which means some form of power extension is required.

An effective solution is to use network cable in a similar way to a USB cable, by supplying both data and power along the same cable. This technique is called Power-over-Ethernet, or PoE.

Ethernet cables are made with eight cables inside, but only four are ever used for transmitting data (the green and orange pairs). The other four cables (the brown and blue pairs) are assigned for passing direct current. In most computer networks, these four cables are never used. The implication being that in many networks, 50% of copper is waisted!

In practice, PoE uses two boxes; the sender and the receiver. The sender box connects to the network and to a power brick. Normally the power brick provides a voltage from 7 to 48 volts DC. The sender box then connects along a single Ethernet cable to the receiver box; which can be up to 100 meters (300 feet) away. The receiver box then splits the single cable back into two; a regular Ethernet cable and a regular power cable.

Importantly, the longer a PoE cable, the greater the voltage drop. This means that a five volt power brick at the sender end, may only muster three volts at the receiver end. Which is insufficient to power a web-camera. With long cable runs, an alternate power brick is necessary.

A protype home built Power-over-Ethernet receiver

An innovation in the world of home networking, this technique borrows the domestic power ring circuit to provide Ethernet connectivity at every power socket in the house. This is called Ethernet over Power (EoP), although sometimes it is called Networking over Mains.

Connecting up is simply a case of plugging a master network adapter into the power socket nearest to the DSL router. Slave network adapters are plugged into power sockets around the dwelling; Ethernet cables are then plugged from the slaves into devices like games machines and web-cameras. If a power socket is in proximity to a web-camera, EoP can be an elegant solution. However, this is not necessarily the cheapest solution and, some power companies prohibit the connection of direct network devices to their power grid.

Although they can go anywhere inside a home, EoP is still an expensive option. The power company should be contacted first to ensure that there are no restrictions when adding EoP devices to their supply.

Installing any cable can present a challenge. Decide on the best path to navigate a cable from the router to the weather web-camera. This could be up into a loft, across and down into another room or, under a carpet and out into the garage.

Good cabling is discrete and safe. Cables should never become trip hazards, so run them along skirting boards, behind cupboards, and where major carpentry is not required, through partition walls and under floorboards. Avoid running cables in parallel contact with mains cables as this may induce interference from electrical devices into the network. When it comes to drilling holes, avoid drilling mystery walls that may contain power, water and gas services. Where cables run outside, they should be insulated an protected.

Cat-5E cable is available in short lengths and longer on economic drums. Measure the exact distance to navigate and then add ten percent; cables have a habit of shrinking twelve inches short of where they need to be!

When threading cables through small apertures, it helps to tape over the cable end to keep the inner strands from pushing out and impeding progress. Terminate both ends of the cable with RJ45 network plugs. For a neater job, at a little more expense, an RJ45 module and patress could be mounted near to the web-camera and router instead of a bare plug. Then, only after testing the network system works, use cable ties, clips and clamps to secure the cable in place.


There are many possible paths for a cable from the router to the web-camera. Typically, the longer the cable run, the greater the difficulty. There is often a distance where a non-cable solution like Ethernet-over-Power or Wi-Fi becomes a practical alternative.

Ethernet cables are terminated with RJ45 connections. Sometimes called modular 8p8c connectors, this means they have eight positions with eight contacts and, they fit into a socket which is sometimes called a module. See the diagram below for the RJ45 connector wiring plan. There is no need to strip the eight cables bare before they are located inside an RJ45 plug. The plug contacts have teeth that bite through the insulation and into the conductor in a technique called insulation displacement. The contacts must be punched down firm in order for a good contact to be made.

An RJ45 crimping tool is a worthwhile investment as it crimps all eight contracts at once. Never push an uncrimped plug into a socket as the still proud contacts will foul inside the socket, and prove a real nuisance to remove!

A correctly assembled RJ45 plug	Untwisting the cable pairs will cause the cable to lose its high speed data integrity

Although unnecessary for most inside wiring jobs, RJ45 connectors can be covered using protective boots. Available in a range of colours, boots are suitable for colour coding the otherwise grey and buff cables. When assembling ad-hoc cables, snag-less boots are preferable. Pictured, an ordinary booted connector (top) and a snag-less boot. See how the blue boot covers the locking tab on the RJ45 plug. This prevents the tab acting like a fishing barb, snagging and then dragging on every other cable in creation. Put boots on the cable before crimping the connectors!

Cat-5 cable colours and their corresponding place within an RJ45 plug. Both plugs at either end of the cable are wired in exactly the same way, making two identical looking plugs.

The astute might ponder that because both RJ45 plugs are the same, is there is actually a need to over-loop the solid green and solid blue coloured cables? In technical terms, provided the cable colour at each position on the both RJ45 plugs are the same, there is no need for over-looping. Devices at either end have no idea of the colour of the insulation being used!

Where there is a need to make-up custom network leads, a few inexpensive tools are a worthwhile and stress-busting expenditure. Pictured, the blue handled device is an RJ45 plug crimping tool. The grey boxes are both ends of an automated cable continuity tester. The red handled clippers are for cutting a clean edge on the Cat-5 cable so the strands will insert into the RJ45 plug without scrunching.

Recent advances in wireless internet mean it is easy to avoid Cable Hell. With a range of around 70 meters (200 feet), a Wi-Fi IP web-camera can prove to be a worthwhile investment.

The wireless web-camera connects to a network in exactly the same way as does a wireless Laptop. Furthermore, they can be configured to exploit the benefits of Wi-Fi security (such as WEP and WPA-PSK). Simply, there is little chance of a web-camera being hijacked by an unauthorised person sat in a nearby parked car with a wireless laptop.

Once again, the availability of a power source should be considered, especially as Wi-Fi web-cameras consume more power than their wired equivalents. Using batteries to power a Wi-Fi camera for more than a few hours is impractical as some cameras consume up to five amp-hours (1 amp at 5 volts over 1 hour). Solar panels charging a battery is an astute solution for powering a remote weather web-camera, but as an energy source, solar is unpredictable and expensive.


With more homes having wireless routers, a wireless web-camera can save a lot of disruption. Although there can be some frustating issues with getting a Wi-Fi web-camera to talk to the network that it is meant to be connected to, on balance, Wi-Fi is often a lot less stress than having to dig up floors and risk puncturing holes in the plumbing!

When installing a Wi-Fi camera, or any other Wi-Fi device, a hot-spot finder or bug sniffer is a useful gadget to have. It quickly confirms if the device is actually transmitting.

• The location of the power supply point is a critical factor with most cameras.
• USB leads provide power but can only run to five meters.
• If the web-camera is remote from a power supply, consider using PoE or EoP.
• Navigate cables responsibly and never compromise on safety.
• Invest in some inexpensive networking tools to avoid stress.
• Always crimp RJ45 plugs before inserting them into a socket.
• Consider using Wi-Fi instead of cables!