This is the eighth chapter of a multi-part series covering all aspects of low voltage wiring in the home: entertainment, security, automation, and future planning.

Pre-Wire Your New Home: Chapter 8: Things To Avoid

David Feller | BOCS Company

Home Technology eMagazine Article

August 2010

Pre-Wire Your New Home: Plan For The Future
Chapter 8: Things To Avoid

Author: David Feller, BOCS Company
This is the eighth chapter of a multi-part series covering all aspects of low voltage wiring in the home: entertainment, security, automation, and future planning. A new section will be published every few weeks.

Pre-Wire Your New Home: Plan For The FutureTable Of Contents:


Chapter 8: Things to avoid


Daisy chain telephone

Yes, you can save wire by installing phone lines the “old fashioned way” and simply string a single wire from room to room, but don’t be fooled. A “Home-Run” installation with each room running all the way back to the media cabinet has huge benefits. It works better with DSL installations, it allows the use of any wire for Data or other applications if you need it, and troubleshooting a faulty wire is much easier.


Share neutral for ceiling fans

A typical ceiling light fed from a switch uses a 2 wire + ground romex cable (14-2 or 12-2 i.e. black, white and bare). If you later decide to install a ceiling fan in that room, the typical installation is to put a dual switch next to the door – one for the light and one for the fan. The temptation is to use the same wire running up to the fan to run both circuits hijacking the black for light, white for fan and bare for neutral leaving off the safety ground altogether. Will it work? Yes, Is it safe? Absolutely not. You have three choices:

  • At the fan location connect the light and fan “black” wires together so the single existing switch controls both. Individual control is then done through the pullchains
  • Install a digital switch specifically for this application. For about $40 you get a wall switch with both light and fan controls and a receiver that is hidden in the wiring box of the fan. It allows a single power line to dole out electricity to either circuit on command of the wall switch. Wireless options are also available
  • Pull a new wire – 3 conductor (Black, Red, white plus bare safety ground) between the switch and the fan


Share Ethernet and phone

Only have a single CatX wire to a room and you need both data and phone? 10MB Ethernet uses only 4 wires and telephone uses 2 so theoretically you can connect both services to the same cable and split them back out at each end into the proper RJ11 and RJ45 jacks. Can you make it work? Yes. But consider the issues:

  • 100MB and Gigabit needs all 8 wires. If you use some for another service you are eternally stuck with a slow data connection.
  • Data connections are low voltage, telephone uses 48V DC plus another 90V on top of that when the phone rings. If the wires ever short or get crossed you are putting 140V peak into an Ethernet jack and the vast majority will fry.
  • If there is significant activity on the phone line or during any ring, the data connection is likely to disconnect or corrupt data. Keep in mind there is no shield of any kind between wire pairs – only the insulation around the wire itself


Only one more chapter to go in this feature - it will be in our next eMagazine issue so stay tuned.


Appendix A: Links to sources, references, and products:

Other good how-to and pre-wire guides:

Products referenced in this guide:


With 20 years in the Consumer Electronics space, David pioneered wireless LAN for home use in partnership with Linksys, rotating storage for portable electronics at Cornice, and is most recently a founder and chief marketing officer of BOCS Inc, the manufacturer of a new whole home A/V distribution system for retrofit applications


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