Conductor Cross Sectional Area | Reference Method C (clipped direct) | Reference Method E (in free air or on a perforated cable tray etc, horizontal or vertical) | Reference Method D (direct in ground or in ducting in ground, in or around buildings) | |||
---|---|---|---|---|---|---|
1 two-core cable single-phase a.c. or d.c. | 1 three-or 1 four-core cable, three-phase a.c. | 1 two-core cable single-phase a.c. or d.c. | 1 three-or 1 four-core cable, three-phase a.c. | 1 two-core cable single-phase a.c. or d.c. | 1 three-or 1 four-core cable, three-phase a.c. | |
1 | 2 | 3 | 4 | 5 | 6 | 7 |
(mm2) | (A) | (A) | (A) | (A) | (A) | (A) |
1.5 | 27 | 23 | 29 | 25 | 25 | 21 |
2.5 | 36 | 31 | 39 | 33 | 33 | 28 |
4 | 49 | 42 | 52 | 44 | 46 | 36 |
6 | 62 | 53 | 66 | 56 | 53 | 44 |
10 | 85 | 73 | 90 | 78 | 71 | 58 |
16 | 110 | 94 | 115 | 99 | 91 | 75 |
25 | 146 | 124 | 152 | 131 | 116 | 96 |
35 | 180 | 154 | 188 | 162 | 139 | 115 |
50 | 219 | 187 | 228 | 197 | 164 | 135 |
70 | 279 | 238 | 291 | 251 | 203 | 167 |
95 | 338 | 289 | 354 | 304 | 239 | 197 |
120 | 392 | 335 | 410 | 353 | 271 | 223 |
150 | 451 | 386 | 472 | 406 | 306 | 251 |
185 | 515 | 441 | 539 | 463 | 343 | 281 |
240 | 607 | 520 | 636 | 546 | 395 | 324 |
300 | 698 | 599 | 732 | 628 | 446 | 365 |
400 | 787 | 673 | 847 | 728 | - | - |
NOTES :
Conductor Cross Sectional Area | Two-core cable d.c. | Two-core cable, single-phase a.c. | Three- or four-core cable, three-phase a.c. | ||||
---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | ||||
(mm2) | (mV/A/m) | (mV/A/m) | (mV/A/m) | ||||
1.5 | 31 | 31 | 27 | ||||
2.5 | 19 | 19 | 16 | ||||
4 | 12 | 12 | 10 | ||||
6 | 7.9 | 7.9 | 6.8 | ||||
10 | 4.7 | 4.7 | 4 | ||||
16 | 2.9 | 2.9 | 2.5 | ||||
r | x | z | r | x | z | ||
25 | 1.85 | 1.85 | 0.16 | 1.9 | 1.6 | 0.14 | 1.65 |
35 | 1.35 | 1.35 | 0.155 | 1.35 | 1.15 | 0.135 | 1.15 |
50 | 0.98 | 0.99 | 0.155 | 1 | 0.86 | 0.135 | 0.87 |
70 | 0.67 | 0.67 | 0.15 | 0.69 | 0.59 | 0.13 | 0.6 |
95 | 0.49 | 0.5 | 0.15 | 0.52 | 0.43 | 0.13 | 0.45 |
120 | 0.39 | 0.4 | 0.145 | 0.42 | 0.34 | 0.13 | 0.37 |
150 | 0.31 | 0.32 | 0.145 | 0.35 | 0.28 | 0.125 | 0.3 |
185 | 0.25 | 0.26 | 0.145 | 0.29 | 0.22 | 0.125 | 0.26 |
240 | 0.195 | 0.2 | 0.14 | 0.24 | 0.175 | 0.125 | 0.21 |
300 | 0.155 | 0.16 | 0.14 | 0.21 | 0.14 | 0.12 | 0.185 |
400 | 0.12 | 0.13 | 0.14 | 0.19 | 0.115 | 0.12 | 0.165 |
DISCLAIMER: This information has been supplied in good faith and the upmost care has been taken to ensure the data is accurate in it's derivation from BS7671.
However, this information should not be considered as a substitute for BS7671, which should always be referred to. It remains the responsibility of the user to ensure all data and assumptions are correct and that any cable used is suitable for its intended purpose.
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