Location, Protection, Ventilation, Markings, Supports, Deformation, Connectors, Capacity, Earthing, Mounting
>>Location: Do NOT install under pipes carrying water, steam, gas ...
>>Protection:
>The racks are for guiding the cables, NOT for projecting them.
>When the nature of the installation requires, suitable COVERS can be
used, or even non-perforated racks. back
>>Ventilation: Cables heat up in
normal use as a result of the current they carry. This heating can vary,
under the same ambient and power conditions, depending on the type of rack
used (open or closed). With less ventilation, larger cables are needed.
>Maximum ventilation: Rejiband, stair.
>Minimum ventilation: closed rack.
>DISTANCE BETWEEN RACKS: To facilitate ventilation, recommended separation
distances are given in mm.
>DISTANCE FROM WALL: When the racks are mounted on wall brackets, a gap of at least 20 mm should be left from the wall to allow for cable ventilation. At PEMSA, all wall supports have a total length of 50 mm more than the width of the rack to be installed, thus guaranteeing compliance with current regulations. back
>>Markings: Racks should facilitate labelling through markings. back
Recommended location for bearing accesories:
>>Deformation in racks and supports: The weight of the cables deforms the racks, this being most evident in the middle of their span. The admissible deformation value (F) is purely for appearances’ sake, making sure that the values given by the manufacturer are not exceeded, this value being, according to the IEC 61537 international standard:
As for the supports, the F max. deformation arises at the ends. The standard recommends F max. = L/20 mm. The deformation value F is called sag, and is expressed in mm.
>>Connectors: The racks are shipped in commercial lengths of 2 or 3 metres. The pieces called CONNECTORS are used for connecting them. For mechanical purposes, the weakest points in a rack installation are the join points. Only the use of the right number of CONNECTORS in the right positions as recommended by the manufacturer can ensure that the entire system will perform satisfactorily.
The ideal spot for employing the CONNECTOR is at L/5 from the nearest support.Fitting the CONNECTORS between L/4 and L/5 is the most advisable approach.
The CONNECTORS should NOT be fitted at point L/2 (half-way between the supports), or on the supports. When L=1.5 meters, which is the commonest case, the use of 3-meter lengths ensures the best placing of the joints, unlike using 2-meter lengths
. 
>>Load
bearing capacity:
This is the load (uniformly distributed, NOT concentrated) that a rack can
safely cope with. It is expressed in kilos or Newtons per running metre,
in the form of graph curves or tables: 1Kg = 9,8 Newtons
The values are obtained through experiments carried out in accordance with
the pertinent standards.
ALL THE LOAD AND PERFORMANCE VALUES GIVEN IN THIS CATALOGUE WERE OBTAINED FROM TESTS CARRIED OUT IN ACCORDANCE WITH INTERNATIONAL STANDARD IEC 61537, 1st Edition, 18/06/1999.
It is often found that similar racks from different manufacturers give different values. This may be due to the load tests not being carried out in accordance with this standard. For proper comparisons to be made between two similar racks from different manufacturers, check that the values given were found under equivalent test conditions. back
>>Earthing (electrical continuity): All metal rack systems must have proper electrical continuity. However, to ensure safety, it is advisable to make an earth connection using a suitable conductor for each part of the system.
This CANNOT be done on painted or epoxy-coated trays without removing the protective layer at that point and at the join-points between the various lengths, which will inevitably lead to oxidisation WITHOUT ENSURING safety. back
>>Through wall mounting: When the racks have to go through a wall, the racks should have a clear space of approximately 100 mm on each side. The earth connection must always be maintained.
If the characteristics of the two rooms separated by the wall are different and may pose risks associated with moisture, gas or fire, the hole in the wall should be blocked off using suitable systems from among those available.
