by Jeff Fisher
In recent years wiring standards for telecommunication devices in the home have become much more sophisticated. The simple quad wire (four wire, non-twisted telephone station wire) that was standard for so many years is no longer acceptable for modern residential systems.
This document provides how to information for selecting and installing telecommunication wiring in your home. It is most useful for pre-wiring a home while the walls are still open. It is also helpful for retrofitting an existing home where updating the telecommunications wiring is needed to support computer connections and other high bandwidth applications.
On this page
- Historical Background
- Telecommunication Wiring Schemes
- The Importance of Using Category Verified Wiring
- Telecommunications Wire
- Connecting Block
- Telecommunications Outlets
- Related Information
Prior to 1980, only telephone company (`telco') employees were allowed by law to install jacks and phone wiring in ones home. A major change was made when the Federal Communications Commission (FCC) issued wiring Docket 88-57, allowing customers and non-telco installers to connect to a telcos wiring system. That has changed. In most instances now, the telco is no longer involved in telecommunications wiring within a residence. The telco wiring responsibility stops at a point referred to as the "demarcation point." This is a point close to where the telephone line enters the home. From this point, the home owner is responsible for the installation of telecommunications wiring to distribute service within the residence. Read on to learn about designing and installing telephone wiring for residences.
Telecommunication Wiring Schemes
Two wiring schemes are common in wiring residences: star and series. We recommend using the star method, which is also called the home run method.
The series method, which we do not recommend, was the normal wiring method used by the telcos before 1980. The series method is often called daisy chaining. This method simply consists of stringing a telephone wire from one jack to the next. It can become quite restrictive when telephone lines need to be reconfigured to accommodate a change in the number of lines serving a residence.
Star or Home Run Configuration
The star, or home run method, consists of running a phone line from each jack or room to a central point in the house. That central point is usually located at or near the point of demarcation where the telcos company office (CO) lines enter the house. By running lines from each room to a common connecting point, as CO lines are added, it is easy to configure each line to serve any desired point in the house. A line added for the computer can be connected to line serving the computer jack, and a new line to serve the children can be connected to jacks in their rooms. This is all done by reconfiguring the connections at the central distribution point.
The figure above shows the TIA preferred residential wiring method. It is a modified star configuration. A cable containing four twisted pairs is fed from each room to a common connection panel in the utility closet. Jacks in the room can be connected to any of the four pair.
The new wire standard for residential installations is four pair Category 3 or better wire.
The Importance of Using Category Verified Wiring
In the days when the telephone company was responsible for wiring in the house, telephone use was much simpler. Usually there was just one line in the house with maybe an extension or two. Simple quad wire was the norm. Modems, answering machines, residential PABX systems, and residential computer networks were either nonexistent or very rare. Quad wire was good enough then, but not now. It doesn't have the circuit capacity, noise immunity, or bandwidth to satisfy today's and tomorrow's residential communication needs.
In order to provide standards for telecommunication wiring, the Telecommunications Industry Association (TIA) has established several specifications. For residential installations, TIA-570 Residential and Light Commercial Wiring Standard is the document for reference.
The recommended wire for residential use is Category 3, 4 pair telecommunications wire.
Levels and Categories
Levels and categories have been established to describe the performance capabilities of different telecommunication wiring methods. Before TIA established a well defined rating system, equipment distributors developed a system of Levels. The only Levels that are still in use are the following:
- Level 1 = Plain Old Telephone Service (POTS)
- Level 2 = IBM Type 3 cabling system
More recently a system of Categories has been established by TIA. The following are descriptions of the Categories:
- Cat 3 = 16 MHz ( 10 Mbps) 100 Ohm UTP
- Cat 4 = 20 MHz ( 16 Mbps) 100 Ohm UTP
- Cat 5 = 100 MHz (100 Mbps) 100 Ohm UTP
For more information on category ratings and data speeds, see Category Cable Ratings.
Category 3 is satisfactory for voice, ISDN, 4Mbps Token Ring, and 10BASE-T. Category 5e or 6 is the new standard for residential installations.
It is important to use verified compliant components for telecommunication installations. Wire and terminals of different performance levels can look the same on the outside. Look at the UL certification to make sure that wiring is verified compliant.
In the old days, quad wire was basically two pair of wire loosely twisted in a jacket. Little attention was given to noise rejection and signal coupling. In most residential installations, it didn't matter much because there was only one line coming into the house. Cross talk wasn't a problem. Frequency band widths were small.
|Quad Wire (aka POTS wire)||Cat 3, 4 Pair Telecom Wire|
With more demanding applications, CAT 5e is needed. Some people are even using CAT 6 for residential use, thinking they might sometime have need for even greater band width. In a 4 pair category rated cable, each pair is twisted together to prevent induction and crosstalk interference from other pairs. The rate of twist for each of the four pair is different to provide additional assurance against coupling. Then the entire bundle of four pairs is twisted to provide further noise rejection. This wire has been carefully engineered. Just ten years ago it was nearly impossible to handle ten megahertz signals in anything but coax. (Remember the days of the big yellow Ethernet coax running around offices?) Engineering advances and new wire making technologies have made communications bandwidths up to 100 megahertz possible on twisted pair. But be careful. To realize good high frequency performance, not only the wire is important. Connectors, jacks, and distribution blocks are also important. A chain is only as strong as its weakest link.
The color code identification for UTP category rated communication cable is shown in the table below.
|Standard 4-Pair UTP Color Codes|
Note that the color organization is four colors: blue, orange, green, and brown, to identify each of the four pair. The polarity of each of the pairs is identified as follows: Less color is tip, more color is ring. The colors are applied with bands of white. If the band of white is larger than the exposed base color, it is tip. If the white band is small compared to the exposed base color, it is ring.
Telephone polarity is labeled tip and ring. This is an artifact from the old switchboards where operators plugged in cords to make a connection. The plugs had a tip connection, and just below the tip was a ring. That labeling system is standard today.
The key to a versatile installation is to have a central distribution point that serves as the center of the star configuration. Every telephone circuit will come to this distribution point. It serves to facilitate initial connections as well as reconfiguration. It is usually located in a utility closet or garage wall near the point of demarcation. The hardware for the central distribution point is called a Connecting Block. There are several types of these blocks.
Insulation Displacement Connectors
The best connecting blocks use insulation displacement connectors (IDC). These are much faster to use and provide a more reliable connection than binding posts with screw terminals. The IDC systems provide a gas tight seal which prevents bi-metal corrosion. IDC connections require a special punch-down tool. Good punch down tools (Impact tool and blade) may seem expensive, but it is worth spending the money. Cheap tools cost much less, but are not recommended. A successful IDC connection requires the right amount of force applied to the right place. Inexpensive punch down tools are erratic in their operation, and the fit is often poor and destructive. Some people try to use common tools, such as needle nose pliers and screwdrivers, for punching down connections. I highly discourage this. Connectors can be damaged in a way where they appear to work, but are unreliable. The gas tight connection is compromised which results in ongoing reliability problems.
Wire Distribution Spools
In order to secure telephone lines in an orderly way where they approach the connection block, wire distribution spools are used. They are screwed into the wall near the connection block so they provide a support for the telephone wires.
It is recommended that you plan to have at least two telecommunications jacks in each room. Often people will place both jacks in the same outlet position using a duplex wall jack. This will allow a computer and a phone to be plugged in at the same location. It is often a good idea to place more than one jack location in a room to allow flexibility in furniture arrangements.
Jacks are normally located at the same level on the wall as power outlets, but not closer than 12 inches to the power outlets. Wall phone brackets with an integral jack are usually mounted near eye level, or a bit lower, on the wall.
It is easiest to install telecommunications wire before the walls are covered. This convenience is rarely available for existing homes.
Wiring Existing Homes
For existing homes, there are a number of ways to rewire telecommunications with modern day wiring. Wires can be routed through the attic, or through the crawl space under the house, then routed through the hollow spaces between the spaces in the wall. The techniques that have been so well developed by the alarm industry for concealing wires also work for telecommunications wiring.
In the case of new construction, or a major remodel, telecommunications wiring should be roughed in before the walls are covered. (See What Wire To Put In When Building A House for additional information.) We run into a number of people who are building new homes for themselves and decide to install the telecommunications wiring themselves. The usually arrange with the general contractor to have access to the project just before rough- in inspection. They then install the telecommunications and video wiring. There are important techniques that need to be used at time of installation to make sure the job is successful.
In order to get top performance from your telecommunications wiring, it has to be installed correctly. As mentioned earlier, getting bandwidths of over one thousand megahertz from twisted pairs is no small feat. The wire alone doesn't get it there. The installation techniques, jacks, and connections are all part of the system and have to be right.
In order to assure that your telecommunications wiring will give you the expected performance, HomeTech sells only top quality wiring supplies and tools. We sell Belden® wire and Leviton® wiring devices. These are the top names in the industry when it comes to quality. Our telecommunication wiring tools and test equipment is by Leviton®, built for the professional trades.
If you are planning to wire your house for telecommunications, there is a good chance you might want to address some other projects at the same time. Here are some ideas
Wiring Your House for Video
Like telecommunications in the home, video distribution equipment has improved and expanded greatly in the past decade. In addition to satellite and cable signals for TV sets in the house, people are now adding many more features. Closed circuit TV sources in the home are becoming quite popular. People want to see what is happening in the side yard or nursery from any TV in the house.
While you are roughing in the telecommunications wire, it is a good idea to also install video cable. The techniques are similar to those used for telecommunications cable. See our Video Distribution Tutorial.
Wiring for Power Line Carrier
The large number of devices available for remote control using the X-10 and UPB power line carrier technology makes this a very useful way of accomplishing home automation. In its simplest form, no real planning needs to be done to prepare for power line carrier use. However, when this technology is used extensively in a home, bridges, noise blocks, amplifiers, and other devices can enhance the performance and reliability of a power line carrier system. Excellent sources of information are the Decora Home Controls Technical Manual and Troubleshooting Home Automation book. These are documents that should be read by anyone planning to build a home, or do extensive remodeling.
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