Electromagnetic compatibility (EMC) - the ability of a device (or system) to operate satisfactorily in its environment without introducing unacceptable electromagnetic disturbance to, or being affected by, that environment - has a significant bearing on cable segregation, as David Oldfield of Draka explained in a previous VoltiTECH. Here, the emphasis is more on segregation in terms of fire alarm cables:
The general requirements of the EMC Directive regarding the performance of 'apparatus' are that it must be constructed so that:
(a) The electromagnetic disturbance it generates does not exceed a level allowing radio and telecommunication equipment to operate as intended.
(b) The apparatus has an adequate level of intrinsic immunity to electromagnetic disturbance to enable it to operate as intended.
The EMC Directive had implications for the cable industry, primarily in the area of the effect of interaction between cable circuits. Even if correctly designed and manufactured equipment is used, incorrectly installed cable connecting equipment to the supply could cause disturbance - possibly causing data corruption in a computer network. Another very important effect to consider is possible interference with safety circuits such as fire alarm systems.
The latter became a major issue in fire alarm system design with the advent of addressable alarm systems in the early 1980s. With the introduction of the EMC Directive, the concerns regarding the potential for interaction between power and data circuits gave rise to joint participation by the ERA / ECA / BCA in investigations concerning the definition of recommended cable separations in circuits so as to achieve EMC in buildings. At the same time, individual cable manufacturers were conducting their own investigations into screening efficiency of their products.
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