Technical Resources
We have gathered together a number of technical resources for use as reference on electrical projects.
DISCLAIMER: The information on this page and the PDF is for information only and R&M Electrical Group Ltd can not be held liable for any information therein.
Conduit and Trunking Capacity Chart
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Cable Spacing Factors
To determing the conduit size needed, multiply the quantities of each size of cable by the appropriate factor, compare the total with the conduit figures shown.
For Example
Question: What size of conduit is required for 6 No. 4mm² cables in a three metre run with no bends?
Answer: 6 x 58 = 348 So the nearest size of coduti with a factor greater than 348 is 20mm.
Conduit Factors
Conduit Diameter (mm) | Capacity Factor |
---|---|
16 | 290 |
20 | 460 |
25 | 800 |
32 | 1400 |
Cable Factors
Single core PVC insulated cables in straight runs of conduit not exceeding 3m in length
Type of Conductor | Conductor cross-sectional area (mmu00b2) | Factor |
---|---|---|
Solid | 1.0 | 22 |
1.5 | 27 | |
2.5 | 39 | |
Standard | 1.5 | 31 |
2.5 | 43 | |
4.0 | 58 | |
6.0 | 88 | |
10.0 | 146 |
Cable Factors
Single core PVC insulated cables in straight runs of conduit exceeding 3m in length OR in runs of any length incorporating bends or sets.
Type of Conductor | Conductor cross-sectional area (mmu00b2) | Factor |
---|---|---|
Solid or Stranded | 1.0 | 16 |
1.5 | 22 | |
2.5 | 30 | |
4.0 | 43 | |
6.0 | 58 | |
10.0 | 105 |
Conduit Capacity Factors (Exceeding 3M in length)
LENGTH OF RUN (m) | CONDUIT DIAMETER (mm) | |||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
16 | 20 | 25 | 32 | 16 | 20 | 25 | 32 | 16 | 20 | 25 | 32 | 16 | 20 | 25 | 32 | 16 | 20 | 25 | 32 | |
STRAIGHT | ONE BEND | TWO BENDS | THREE BENDS | FOUR BENDS | ||||||||||||||||
1.0 | - | - | - | - | 188 | 303 | 543 | 947 | 177 | 286 | 514 | 900 | 158 | 256 | 463 | 818 | 130 | 213 | 388 | 692 |
1.5 | - | - | - | - | 182 | 294 | 528 | 923 | 167 | 270 | 487 | 857 | 143 | 233 | 422 | 750 | 111 | 182 | 333 | 600 |
2.0 | - | - | - | - | 177 | 286 | 514 | 900 | 158 | 256 | 463 | 818 | 130 | 213 | 388 | 692 | 97 | 159 | 292 | 529 |
2.5 | - | - | - | - | 171 | 278 | 500 | 878 | 150 | 244 | 442 | 783 | 120 | 196 | 358 | 643 | 86 | 141 | 260 | 474 |
3.0 | - | - | - | - | 167 | 270 | 487 | 857 | 143 | 233 | 422 | 750 | 111 | 182 | 333 | 600 | - | - | - | - |
3.5 | 179 | 290 | 521 | 911 | 162 | 263 | 475 | 837 | 136 | 222 | 404 | 720 | 103 | 169 | 311 | 563 | - | - | - | - |
4.0 | 177 | 286 | 514 | 900 | 158 | 256 | 463 | 818 | 130 | 213 | 388 | 692 | 97 | 159 | 2925 | 529 | - | - | - | - |
4.5 | 174 | 282 | 507 | 889 | 154 | 250 | 452 | 800 | 125 | 204 | 3736 | 667 | 91 | 149 | 275 | 500 | - | - | - | - |
5.0 | 171 | 278 | 500 | 878 | 150 | 244 | 442 | 783 | 120 | 196 | 358 | 643 | 86 | 141 | 260 | 474 | - | - | - | - |
6.0 | 167 | 270 | 487 | 857 | 143 | 233 | 422 | 750 | 111 | 182 | 333 | 600 | - | - | - | - | - | - | - | - |
7.0 | 162 | 263 | 475 | 837 | 136 | 222 | 404 | 720 | 103 | 169 | 311 | 563 | - | - | - | - | - | - | - | - |
8.0 | 158 | 256 | 463 | 818 | 130 | 213 | 388 | 692 | 97 | 159 | 292 | 529 | - | - | - | - | - | - | - | - |
9.0 | 154 | 250 | 452 | 800 | 125 | 204 | 373 | 667 | 91 | 149 | 275 | 500 | - | - | - | - | - | - | - | - |
10.0 | 150 | 244 | 442 | 783 | 120 | 196 | 385 | 643 | 86 | 141 | 260 | 474 | - | - | - | - | - | - | - | - |
To determine the trunking size needed, multiply the quantities of each cable by the appropriate factor, and compare the total with the trunking capacity figures shown.
For example: What size of standard trunking is needed for 10 in number 35mm² cables and 16 in number 4mm² cables?
The nearest size of standard trunking with a capacity factor greater than 1239.6 is 75 x 50mm?
(No. of Cables) 10 x 95 (Factor for 35mm² cable) = 950
(No. of Cables) 16 x 18.0 (Factor for 4mm² cable) = 289.6
Total Cable Factor = 1239.6
Standard Trunking Cable Factors
Nominal Conductor size mmu00b2 | 1.5 Solid | 1.5 Standard | 2.5 Solid | 2.5 Standard | 4 | 6 | 10 | 16 | 25 | 35 | 50 | 70 | 95 |
Factor copper or aluminium | 8.6 | 9.6 | 11.9 | 13.9 | 18.1 | 22.9 | 36.3 | 50.3 | 75.4 | 95 | 133 | 177 | 227 |
Standard Trunking Capacity Factors
Trunk Size | Capacity Factor | Trunk Size2 | Capacity Factor3 |
---|---|---|---|
50mm x 50mm | 1,037 | 150mm x 75mm | 4,743 |
75mm x 50mm | 1,555 | 150mm x 100mm | 6,394 |
75mm x 75mm | 2,371 | 150mm x 150mm | 9,697 |
100mm x 50mm | 2,091 | 200mm x 100mm | 8,572 |
100mm x 75mm | 3,189 | 225mm x 150mm | 14,652 |
100mm x 100mm | 4,252 | 300mm x 150mm | 19,607 |
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