Planning Ahead When Wiring Your Home or Office

by Brian McConnell

This is a common situation. Someone hires an electrical contractor to do their phone wiring. They think everything is being done correctly, but then they find out (after the fact), that the wiring has been run incorrectly. If you are planning to wire your home or office, this short tutorial explains how to install your wiring so that you can use any type of telephone system in the future, either a KSU-less (intercom) system, a key system, or a PBX or telephony server. If you are hiring a contractor to do your wiring for you, print this article out and give it to your installer.

"Daisy Chain" wiring - a recipe for trouble
Many contractors will install your phone wiring in daisy chain fashion unless told otherwise. This causes problems because you have one common set of wires for all of your phone jacks. This is bad. Many phone systems require so-called "star" wiring where each phone jack has its own cable running back to a central wiring point.

Fig. 1. "Daisy Chain" wiring

Installing your wiring to work with all types of systems
The trick to futureproofing your phone wiring is to wire your home or office in a star configuration. This means that each phone jack has its own wires running back to a central wiring point. The central wiring point is either a punchdown block or a patch panel. A punchdown block is a panel of metal pegs to which the wires are connected. A patch panel is easier to deal with. It has a bank of RJ-14 modular phone jacks to which the wiring is connected. Ask your wiring contractor to install a combination punchdown block/patch panel. This is a punchdown block which has a row of modular phone/data jacks on the side. This makes it easy to connect external phone lines, telephone switching equipment, etc., using only modular phone/data patch cords.

Fig. 2. Star Wiring configuration - each phone jack is independently wired to the central point.

In homes, KSU-less or intercom systems are very popular. These are also easy to install and use. They generally use loop or daisy chain wiring, while more sophisticated systems use star wiring configurations.

If you wire your home or office according to the diagram above, you can easily reconfigure your wiring from a star configuration to a loop or daisy chain configuration without rewiring your phone jacks. By making some minor changes at the punchdown block, you can bridge all of your phone jacks together for use with a KSU-less or intercom system. If you later decide to upgrade to a system which requires a star configuration, all you need to do is to remove some connectors from your punchdown block to turn these back into separate circuits. Your wiring contractor will know how to do this.

Types of wiring used by different phone systems

System Type Wiring Configuration
KSU-less (Intercom) System Loop/Daisy Chain
Key System Star
PBX Star
PC Telephony Server Star
LAN Telephone System Star
Wireless Systems Either

LAN wiring
If you are going through the trouble of rewiring your home or office for voice, you should have your contractor install a second set of jacks for high-speed data service (i.e., Ethernet). Unless you are planning to be running very high-speed services out of your home, Category 3 wiring, rated to carry 10 megabit Ethernet service, should be sufficient. Data wiring should always be wired in a star configuration, and should use shielded, twisted-pair cable designed to minimize interference and signal loss. Do not use standard phone wire for Ethernet cabling. Your installer should also have a 10BaseT test set so that he or she can verify that the cable is OK, and is capable of carrying Ethernet signals without errors.

The LAN cable runs will, in turn, be connected to an Ethernet hub or switch which is located near the central wiring point. If you anticipate having many computers sharing your LAN, with a lot of data traffic, we recommend using an Ethernet switch. Ethernet switches provide higher effective speeds than Ethernet hubs, which are cheaper. Ethernet hubs are perfectly adequate for typical home uses though. You wire your Ethernet cable runs to the hub or switch, and then you have high-speed data "dialtone" running throughout your house.