The following information will assist you to select the size of trunking for the required number and size of cable in your installation.
Cable table
solid
Stranded
solid
Stranded
Normal conductor size mm   1.5   1.5   2.5   2.5   4   6   10   16   25   35   50   70   95 120   150   240  
Factor copper or aluminum 1.7   8.1   10.2   11.4   15   22   38   50   75   95   133   177   227 284   346   552
To determine trunking size:
Using the cable table above multiply the quantities of each size of cable by the appropriate factors, to determine the capacity units required.Then, using the trunking size table below select the trunking size which has the nearest higher capacity figure.
Example
:What trunking size is needed to run 24 x 16mm cables and 36 x 6mm cables?
Quality   Factor Sub   total
               
24 x  50  = 1,200
36 x  22  = 792
 
Total 1,992
Using the trunking size table below, the trunking size required is 100x50 as this has the next higher figure for capacity units.
These tables are bassed on a theroretical calculation and must be taken only as a guide, due regard must be taken of future wiring needs.These figures are bassed on the I.E.E.
Trunking size table
Trunking size mm Capacity units Trunking size mm Capacity units
                     
50 x 50   1037   225 x 50   4646
75 x 50   1555   225 x 75   7114
75 x 75 2371 225 x 100 9298
  225 x 150 14652
100 x 50 2091 225 x 225 21766
100 x 75 3189
100 x 100 4252 300 x 50 6182
  300 x 75 9486
150 x 50 3091 300 x 100 12788
150 x 75 4742 300 x 150 19447
150 x 100 6394 300 x 300 38894
150 x 150 9697  -----  -----