Cable Supoort

Low Voltage Cables on Ladder or Tray

BS 7671 (2008 +A3), regulations 522.8.4 and 522, require that if conductors are not continuously supported, that they shall be supported at suitable intervals to ensure sure they are not damaged due to their own weight.  The cable shall also be supported in such a way so as not to place any strain on any terminations.

The Onsite Guide to BS 7671, table 4a gives suggested maximum spacing for support clips:

 

Table 4a Maximum Spacing of Clips (mm)
  Non-armoured thermosetting or thermoplastic (PVC) sheathed cables    
Overall diameter of cable, d* (mm) Generally  In caravans Armoured cables Mineral insulated copper sheathed or aluminium sheathed cables

1		 Horizontal
2		 Vertical
3		 Horizontal
4		 Vertical
5		 Horizontal
6		 Vertical
7		 Horizontal
8		 Vertical
9
d ≤ 9 250 400 250 400 - - 300 800
9 < d ≤ 15 300 400 250 400 350 450 900 1200
15 < d ≤ 20 350 450 250 400 400 550 1500 2000
20 < d ≤ 40 400 550 250 400 450 600 - -

Note: for the spacing of supports for cables having an overall diameter exceeding 40 mm, the manufacturer’s recommendation should be observed.
* for flat cables taken as the dimension of the major axis.
† the spacings stated for horizontal runs may be applied also to the runs at an angle of more than 30º from the vertical. For runs at an angle of 30º or less from the vertical, the vertical spacings are applicable. 

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