conduit entries to equipment

provided that the lower voltage circuits are insulated for the highest voltages present , it is better not to do so . BS 6701 :1994 recommends that there be a minimum distance between mains (Bands II ) and telecommuinication circuits ( Band I ).
  THe next matter to receive our attention is how to fix conduit . FIgure 3.10 shows various devices for fixing conduits . THe pipehook or crampet , Figure 3.10 is a satisfactory and simple fixing , but is too unsightly to be used on surface work . It can be driven into timber , brick or masonry , but is more likely to be dislodged than a screwed fixing ; where the conduit is to be buried in plaster after it has been fixed , this does not matter because the plaster will hold the conduit in place , but where the conduit is to remain exposed a firmer fixing is desirable . THe saddle hook shown in Figure 3.10b is by far the commonest fixing . It passs round the conduit and is secured to the wall by two screws . THe olny advantage of the clip shown in Figure 3.10c is that it saves one screw . It is not as secure as the saddle and the cost saving is not sufficient for a good engineer to use it .
  Sockets and other conduit fittings necessarily have a larger outside diameter than the conduit itself . If these components are tight to a wall , the conduit must be slightly proud of the wall . Because of this , when an ordinary saddle is tightened , it will tend to distort the conduit . THis can be prevented by the use of a spacer saddle , Figure 3.10 d . which has the same thickness as the sockets . The spacer saddle has the further advantage that it prevents the conduit from touching damp plaster and cement which could corrode ad discolour decoration .
  When conduit is fixed to concrete , the time taken to drill and plug holes in the concrete is a very large proportion of the installastion time . A spacer bar saddle has olny one screw to be fixed to the wall and the saving in tie can be greater than the extra cost of the material .
  The distancesaddle shown in Figure 3.10e holds the conduit about 10mm from the wall . THis spacing eliminats the ledge betweent the conduit and the wall where dust can collect and makes it possible to decorate the wall behind the conduit . It also makes it impossible for minute drops of moisture to collect in the crack between conduit and wall and thus reduces the possibilities of corrosion . For these reaseons , distance saddles are almost invariably specified by hospotal boars and local authorities for surface conduit .
  Conduit often runs across or along stel girders or joist , either exposed or within a false ceiling . It is not desirable to drill and tap structural  steelwork and it is better to use girde  clips of the type illustrated in Figure 3.10f . Whilst standard girder clips can be bought from conduit manufacturesrs , it is usually simpler to make special clips to suit individual condition on each job . FOr multipple run and runs with other services , uni-struct is often used .         

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