Difference between revisions of "Wiring Considerations"

Revision as of 15:35, 22 March 2010

Introduction

Older, proprietary home automation and security systems traditionally have required their own dedicated wiring. Placing that wiring was often the biggest hurdle in installing such systems, and usually entailed tearing open walls in order to run the special cables (which was often very thick and difficult to manage).

In contrast, LinuxMCE uses standard Ethernet wiring and jacks. Because it is IP (Internet Protocol) based (the same protocol that runs the Internet and most local home and office networks), it runs directly over an Ethernet network. Ethernet networks use standard CAT5 (or CAT5e/CAT6) wiring with RJ-45 jacks. This wiring is often already pre-installed in recently-constructed homes, since it is now also used for many phone systems as well as for home networks. Even if your home does not already have CAT5e/CAT6 wiring pre-installed, CAT5e/CAT6 wires are some of the smaller, easier wires to install. Installing CAT5e/CAT6 wiring in a house is well worth the cost and will increase the resale value, even without a LinuxMCE system. Home networks (LANs) that are run over CAT5e-wired Ethernet connections are increasingly popular for Internet access and file/printer sharing throughout the home.

Thus, the only wiring requirement for LinuxMCE is that you have Ethernet (CAT5e/CAT6) wiring. All wired LinuxMCE devices (such as a PC used as a Media Director) will be able to directly plug into the RJ45 jack.

Wired vs. wireless connections

Note, however, that not all LinuxMCE devices require a wired connection. Many can connect wirelessly, if you have a wireless access point connected to the LinuxMCE Core server. However, it is easiest for the main components, the Core and the Media Directors, to be connected in a wired fashion.

CAT5 vs. CAT5e vs. CAT6 vs. Fiber-optic

• CAT5 wiring uses the smallest gauge wires, which are stranded. It was the standard for many years and can be used for data speeds up to 100 Mb/sec. However, the increased speeds and loads of modern LANs place a strain on the characteristics of this wire. It is no longer recommended as the wiring standard. In general 100 Mb/sec speeds can transmit 7 simultaneous DVD quality video streams.

• CAT5e wiring was recently used as the wiring standard, and uses a somewhat higher gauge solid wire. This enables the transmission of data at 250 Mb/sec to 1000 Mb/sec (Gigabit), used by newer LANs. At these speeds, it is more reliable over long distances. In general, Gigabit data transmission speeds can transmit 100 simultaneous DVD quality video streams (over short distances).

• CAT6 wiring uses even higher gauge wires. It is preferred for Gigabit speeds (1000 Mb/sec to 10,000 Mb/sec), especially over long distances. Until recently, such speeds were not common, but rapid advancements in routers have made Gigabit networks the norm. Therefore, CAT6 wire should be installed whenever possible.

Obviously, even if you use higher gauge CAT5e and CAT6 wires, you will not achieve the higher data transmission speeds unless all your network components (cables, connectors, network cards, switches, etc.) also support higher data transmission speeds.

• Fiber optic cables theoretically have the highest transmission rate, but are currently expensive and difficult to install (because if they are bent during installation the fibers can break). Routers to connect to fiber optic cables are not readily available for the consumer, either. However, this is the ultimate in forward-thinking cabling for your house, and it will not be long before fiber optic cable will be standard in home construction. Fiber optic cables will replace your phone, television cable, and ethernet cables, so that one fiber optic cable will carry all those signals.

• Many commercial buildings use conduits for cabling, to allow easy cable runs and replacement of existing cables in the future. Conduits can be made of simple PVC pipes (like those used for irrigation), but most builders are reluctant to install them. Nevertheless, they do not take much effort to install during a new home construction, are not expensive, and provide superior protection for cables, especially fragile fiber optic cables. They will also prevent chewing on cables by varmints (such as squirrels and mice).

Using pre-installed CAT5 placed for telephone systems

It is possible but not wise to use the same wire for the telephone system and the LAN (see the discussion page for more details). Telephone systems run their own power over the CAT5 lines in a configuration different from Ethernet devices. If you connect an Ethernet device to a live telephone line, you can burn out the Ethernet device unless you are very careful about tracing the leads. While some users have wired analog phone and ethernet on the same CAT5 wire, it is strongly discouraged.

However, most new telephone installations include redundant CAT5 wires that are not connected to the telephone system. (For example, my home is wired with two CAT5 wires to each location, one connected to a telephone jack and one left unconnected.)

It is very easy to use a redundant CAT5 wire for the LAN by connecting it to an additional RJ-45 jack, which can then be added to the same outlet. The wire must then be traced to the other end, which will almost always be at the telephone patch panel for your home (where hopefully it will also be unconnected) and connected to the LAN there, instead. (This presumes, of course, that at the location of the telephone patch panel you have a router, switch, or RJ45 connection (to the rest of your LAN) to which you can connect this wire (using an RJ-45 connector).)

Ethernet wiring standards

It is important to note that there are two wiring standards for Ethernet, T568A and T568B. My local electrician was clueless about this and wired all my CAT5 connections wrong.

For a quick tutorial, see this guide on wiring Ethernet connections.

Most Ethernet wiring is currently done using the T568B standard, and I highly recommend you stick to it. However, you must be aware of deviations from this standard. For example, my Ethernet-wired surveillance cameras all use the T568A standard. This took me a long time to figure out, and, again, my electrician wired them all incorrectly.

It is tricky to adapt T568A to T568B -- you need a special type of cross-over cable. This is somewhat complex. For the most part, I recommend you just wire everything using the T568B standard.

Audio cabling

In some instances, you may wish to install cabling for audio signals (line in/out audio, speakers, etc.) to or from your LinuxMCE system. If an audio cable is close to the power lines, the audio cable will pick up 50 or 60 Hz frequency power line noise. This will cause a "humming" in your audio signal which is very annoying. In general low-volt audio wires should be at least 18 inches away from power lines, not run parallel to power lines for more than 2 feet, and should cross perpindicular to power lines whenever possible. If you are planning to install audio cabling in your home, take a look at the Whole-House Audio Tutorial from HomeTech Solutions. (It is not LinuxMCE specific but is very informative.)

Also see: What is proper CAT5 cabling? In-wall Wiring Guide