HOME AUTOMATION TIPS
The following tips are the result of bitter experience of how and how not to go about the cabling.
1. Always run non mains cable (CAT 5, Speaker, Coax, Security) at least 4 inches away from main cable. The AC field from a mains cable extends indefinitely in theory, but it is governed by an inverse square law, so the field actually drops off in strength in proportion to the square of the distance, i.e. in a reasonably short distance. The greater the distance that separates mains and non-mains cables, the less the chance that the AC mains will induce a voltage in the non-mains cable. Some would say the distance should be several feet, but I have not found any problems at distances of less than a foot when using shielded twisted pair CAT 5 cable for data and phones, and with coax cable and speaker cable. In fact, I carried out a test with coax cable from a CCTV laid next to main cable, and then run approximately 20 feet, and the signal did not display any visual degradation
If the cables are run too close together, the mains cable can induce a voltage in the non mains cable, which will manifest itself as noise - such as the hum that can be heard on speakers when a hi-fi system is on.
2. High impedance signals such as those for microphone cable are very susceptible to interference from an AC mains field.
3. Low impedance signals such as those for speaker cable are far less susceptible to interference from an AC mains field.
4. Always try and ensure that if mains and non mains cables need to cross, that they cross at 90 degrees.
5. Label all cables clearly. Even better, use a labelling machine.
6. Ensure you have enough slack in the cables should you need to cut off more than anticipated.
7. Do not plug any connections from phone lines into data systems such as Hubs or Switches. The phone lines operate at much higher voltages than data systems, so plugging any phone line into a Hub or Switch will likely result in the destruction of the device.
8. Try and terminate ends of cables with connectors rather than hard wiring where possible. You'd be surprised how time consuming it can be to unwire systems that have been hardwired, whereas using connectors, cables can be plugged and unplugged with ease. This is especially the case with RF (TV, Satellite), and even security and home audio.