Selecting Trunking Size
To determine the required trunking size, multiply the number of each size of conductor by the factor appropriate to their size as given in Table A, sum the results for all conductors and select the trunking by comparing this sum with the maximum capacity units given in Table B.
This method is based on theoretical calculation and is useful as a general guide.
Other factors such as whether cables will cross or whether future changes will require the trunking to accept additional cabling must be taken to account into selection. |
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Table A |
Cable Size mm2 |
Factor*
Copper or Aluminum |
1.0 |
8.1 |
1.5 |
9.1 |
2.5 |
11.4 |
4.0 |
16.6 |
6.0 |
21.3 |
10.0 |
33.1 |
16.0 |
45.5 |
25.0 |
68.0 |
35.0 |
90.0 |
50.0 |
123.1 |
70.0 |
158.0 |
95.0 |
214.0 |
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Table A |
Trunking Size mm |
Capacity Units |
50 x 50 |
1080 |
75 x 50 |
1620 |
75 x 75 |
2450 |
100 x 50 |
2170 |
100 x 75 |
3280 |
100 x 100 |
4390 |
150 x 75 |
3900 |
150 x 100 |
6570 |
150 x 150 |
9910 |
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