Office Wiring: Mishaps, Missteps and Mayhem

Your company just leased new office space and YOU are in charge of ensuring the internal computer and telephone wiring is in-place and working on move in day.

In a nutshell, these are the steps you need to take:

  • choose the right cable
  • test the cable
  • make a detailed floor plan and tag and clearly label your cable and jacks
  • spec brand name cable to your wiring contractor

There are two common grades of computer cabling: Category 5E or CAT 6 (and now there is also a 6A with improved specs over “6”.)  Check Wikipedia for info on CAT 5 and 5E or this article on CAT 6 to help you decide. Cost-wise, CAT 6 will be higher by about 30% or more.

I always  suggest a trip to Home Depot to pick up an Ethernet cable tester (around $60). What you’ll get are two little boxes…you plug the remote into a jack, and the master at the other end, press a button, and if all is working according to plan it lights up 4 green LED’s to tell you you’ve got continuity and correct polarity on all four pairs.

This is important because 100 Mbps Ethernet runs on two pairs, however 1000 Mbps and / or P.O.E. (Power over Ethernet) uses all 4 pairs… and some contractors have been known occasionally to only connect the two active pairs used for “Fast” Ethernet, which refers to the 100 Mbps variety.

A detailed floor plan is vital, along with clear labeling and a numbering plan for the jacks.  Be sure to ask what method they use to label the jacks – or you just may end up with handwriting. Handwriting will not last the test of time, and is therefore not acceptable.

If you’re reusing existing cabling, it still should be toned, tagged and tested.

Ask what brand of cable they use, and don’t be afraid to spec a brand name: Beldin, Pirelli and General Cable are 3 that spring to mind. Visit the site while work is in progress to confirm you’re getting what you asked and paid for.

Why? There’s a ton of cheap cable from overseas that often doesn’t meet spec which may lead to problems with your network.

Expect the unexpected when you’re moving into new office space. Anything can happen… for example… you rent a space that you only viewed while occupied. Seeing computer wiring in the walls everywhere, it’s easy to think you’re covered. The current tenant moves out, and the property manager rips out all the computer and telephone wiring before they turn over the key. Better safe than sorry, check with the property manager and ask if that’s part of their protocol.

Questions or comments?

Please email Robert McNulty at, or tweet me @SkywayWest_VoIP