Noise on cables

The most common cause of noise pick-up on data cables is from fluorescent lighting. Lynx Networks were called to a site last week to investigate a noise problem and it turned out that the installer had run the cabling adjacent to a row of lighting and right over a light fitting in the comms room.

A good cabler will know to keep cables away from fluorescent lighting but an untrained cabler may not. Testing with a Fluke DSR400 or DTX tester, or equally good device, will warn the operator of the presence of noise will not record it in the stored results. This is because noise is not part of the TIA, EN or ISO physical layer specifications. So, be warned, a poor cabler, and there are plenty of them around, can get away with badly routed cables. However, your network may not be as tolerant. The result will be network failure, garbled VoIP telephony or loss of speed.
Alan Bullen
Lynx Networks plc