Improperly installed cabling can be a contributor to electromagnetic interference (EMI) on a network. EMI problems for telecommunications systems can only occur under three simultaneous conditions, which are:
- An interfering source (transmitters, motors, switches, electrical power lines, common fluorescent light fixtures)
- A susceptible unit (receivers, sensitive electronic components, relay equipment)
- A coupling path between the interfering source and the susceptible unit (network cabling)
Equipment designed to operate over balanced twisted-pair cabling uses a balanced (e.g., differential-mode) signal at the output of the transmitter. For such systems, it is important to ensure that the cabling elements are well balanced and that the pairs are not excessively untwisted at the point of termination.
Cabling systems (e.g., improperly grounded shielded or unshielded) in buildings are effective antennae for receiving and transmitting radiation from ESD events. As such, they affect the ability of equipment to withstand ESD.
Telecommunications installations that experience malfunctions and failures often have one or more problems in the electrical power and grounding systems.
Minimum separation distances from possible sources of electromagnetic interference exceeding 5 kVA
- Unshielded power lines or electrical equipment in proximity to open or nonmetal pathways. 610 mm (24 in)
- Unshielded power lines or electrical equipment in proximity to a grounded metal conduit pathway. 305 mm (12 in)
- Power lines enclosed in grounded metal conduit (or equivalent shielding) in proximity to a grounded metal conduit pathway. 152 mm (6 in)
- Electrical motors and transformers. 1194 mm (47 in)
Links to interesting articles: Silence Noise on Your Network