Fire Resisting Cable

Fire Resisting Cables

Current Rating and Voltage Drop

Single Core Cables having XLPE Insulation, Unarmoured (Copper Conductor) 600/1000V

Current-Carrying Capacities (Amp) XLPE/PVC Cables
Size of Conductor Reference Method 4 (Enclosed in conduit in thermally insulating wall etc) Reference Method 3 (Enclosed in conduit on a wall or in trunking etc) Reference Method 1 (Clipped direct) Reference Method 11 (on a perforated cable tray, horizontal or vertical) Reference Method 12 (free air)
2 cables 1-phase ac or dc 3 or 4 cables 3-phase ac 2 cables 1-phase ac or dc 3 or 4 cables 3-phase ac 2 cables 1-phase ac or dc flat & touching 3 or 4 cables 3-phase ac flat & touching or trefoil 2 cables 1-phase ac or dc or flat & touching 3 or 4 cables 3-phase ac flat & touching trefoil 3 cables trefoil 3-phase ac
1 mm² 2 A 3 A 4 A 5 A 6 A 7 A 8 A 9 A 10 A
1.5 18 17 22 19 25 23 - - -
2.5 24 23 30 26 34 31 - - -
4 33 30 40 35 46 41 - - -
6 43 39 51 45 59 54 - - -
10 58 53 71 63 81 74 - - -
16 76 70 95 85 109 99 - - -
25 100 91 126 111 143 130 158 140 138
35 124 111 156 138 176 161 195 176 171
50 149 135 189 168 228 209 293 215 209
70 189 170 240 214 293 268 308 279 270
95 228 205 290 259 355 326 375 341 330
120 263 235 336 299 413 379 436 398 385
150 300 270 375 328 476 436 505 461 445
185 341 306 426 370 545 500 579 530 511
240 400 358 500 433 644 590 686 630 606
300 459 410 573 493 743 681 794 730 901
400 - - 683 584 868 793 915 849 820
500 - - 783 666 990 904 1044 973 936
630 - - 900 764 1130 1033 1191 1115 1069
800 - - - - 1288 1179 1358 1275 1214
1000 - - - - 1443 1323 1520 1436 1349

Note: Rating factors for ambient temperature other than 30℃ please refer Table C

Rating factors for ground temperature other than 15℃ please refer Table D

Group Rating Factor please refer to Table F & Table G

Voltage Drop (Per Amp Per Meter) XLPE/PVC Cables
Size of Conductor 2 cables dc 2 cables 1-phase ac 3 or 4 cables 3-phase ac
Reference Methods 3 & 4 (Enclosed in conduit etc, in or on a wall) Reference Methods 1 & 11 (Clipped direct or on trays touching) Reference Methods 3 & 4 (Enclosed in conduit etc, in or on a wall) Reference Methods 1, 11 & 12 (in trefoil) Reference Methods 1 & 11 (Flat touching)
1 mm² 2 mV/A/m 3 mV/A/m 4 mV/A/m 5 mV/A/m 6 mV/A/m 7 mV/A/m
1.5 31 31 31 27 27 27
2.5 19 19 19 16 16 16
4 12 12 12 10 10 10
6 7.9 7.9 7.9 6.8 6.8 6.8
10 4.7 4.7 4.7 4.0 4.0 4.0
16 2.9 2.9 2.9 2.5 2.5 2.5
    r x z r x z r x z r x z r x z
25 1.85 1.85 0.31 1.90 1.85 0.19 1.85 1.60 0.27 1.65 1.60 0.165 1.60 1.60 0.19 1.60
35 1.35 1.35 0.29 1.35 1.35 0.18 1.35 1.15 0.25 1.15 1.15 0.155 1.15 1.15 0.18 1.15
50 0.99 1.00 0.29 1.05 0.99 0.18 1.00 0.87 0.25 0.90 0.86 0.155 0.87 0.86 0.18 0.87
70 0.68 0.70 0.28 0.75 0.68 0.175 0.71 0.60 0.24 0.65 0.59 0.150 0.61 0.59 0.175 0.62
95 0.49 0.51 0.27 0.58 0.49 0.170 0.52 0.44 0.23 0.50 0.43 0.145 0.45 0.43 0.170 0.46
120 0.39 0.41 0.26 0.48 0.39 0.165 0.43 0.35 0.23 0.42 0.34 0.140 0.37 0.34 0.165 0.38
150 0.32 0.33 0.26 0.43 0.32 0.165 0.36 0.29 0.23 0.37 0.28 0.140 0.31 0.28 0.165 0.32
185 0.25 0.27 0.26 0.37 0.26 0.165 0.30 0.23 0.23 0.32 0.22 0.140 0.26 0.22 0.165 0.28
240 0.19 0.21 0.26 0.33 0.20 0.160 0.25 0.185 0.22 0.29 0.17 0.140 0.22 0.17 0.165 0.24
300 0.155 0.175 0.25 0.31 0.16 0.160 0.22 0.15 0.22 0.27 0.14 0.140 0.195 0.135 0.160 0.21
400 0.12 0.14 0.25 0.29 0.13 0.155 0.20 0.125 0.22 0.25 0.11 0.135 0.175 0.110 0.160 0.195
500 0.093 0.12 0.25 0.28 0.105 0.155 0.185 0.100 0.22 0.24 0.09 0.135 0.160 0.088 0.160 0.180
630 0.072 0.10 0.25 0.27 0.086 0.155 0.175 0.088 0.21 0.23 0.074 0.135 0.150 0.071 0.160 0.170
800 0.056 - - - 0.072 0.150 0.170 - - - 0.062 0.130 0.145 0.059 0.155 0.165
1000 0.045 - - - 0.063 0.150 0.165 - - - 0.055 0.130 0.140 0.050 0.155 0.165

Note: r=conductor resistance at operating temperature

Z=impedance, x=reactance

Table C: Rating Factors for Other Ambient Air Temperatures (XLPE Insulated)

Ambient Temperature 25℃ 30℃ 35℃ 40℃ 45℃ 50℃ 55℃ 60℃ 65℃ 70℃ 75℃ 80℃ 85℃
Rating Factor 1.02 1.00 0.96 0.91 0.87 0.82 0.76 0.71 0.65 0.58 0.50 0.41 0.29

Table D: Rating Factors for Other Ground Temperatures (XLPE Insulated)

Ground Temperature 15℃ 20℃ 25℃ 30℃ 35℃ 40℃ 45℃ 50℃
Rating Factor 1.00 0.97 0.93 0.89 0.86 0.82 0.77 0.73

Table F: Group Rating Factors for Cables Installation

Group Rating Factors Number of Circuits
2 3 4 5 6 7 8 9 10 11 12
1 For circuits of 2 Single core cables laid flat touching horizontal formation, laid direct in ground 0.79 0.68 0.62 0.57 0.54 0.52 0.50 0.48 0.47 0.46 0.45
2 For circuits of 3 Single core cables in trefoil touching, laid direct in ground 0.78 0.66 0.61 0.56 0.53 0.50 0.49 0.47 0.46 0.44 0.43
  Number of Cables in a Group
2 3 4 5 6 7 8 9 10 11 12
3 For twin or multi-cores cables in horizontal formation, laid direct in ground Spaced 0.15m 0.87 0.78 0.74 0.70 0.68 0.66 0.64 0.63 0.62 0.61 0.60
Spaced 0.30m 0.91 0.84 0.81 0.78 0.77 0.75 0.75 0.74 0.73 0.73 0.72
      Number of Ducts in a Group
      2 3 4 5 6 7 8 9 10 11 12
4 For twin or multi-cores cables in single-way ducts horizontal formation spaced 0.30m apart 0.93 0.88 0.85 0.83 0.82 0.81 0.80 0.79 0.79 0.78 0.78
Table G Correction Factors for Groups of More than One Circuit of Single Core Cables, or More than One Multi-Cores Cable
Reference Methods of Installation Correction Factor (Cg)
  Number of Circuits or Multi-cores Cables
  2 3 4 5 6 7 8 9 10 12 14 16 18 20
Enclosed (Method 3 or 4) or bunched and clipped direct to a non-metallic surface (Method 1) 0.80 0.70 0.65 0.60 0.57 0.54 0.52 0.50 0.48 0.45 0.43 0.41 0.39 0.38
Single layer clipped to a non-metallic surface (Method 1) Touching 0.85 0.79 0.75 0.73 0.72 0.72 0.71 0.70 - - - - - -
Spaced* 0.94 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90
Single layer multi-cores on a perforated metal cable tray, vertical or horizontal(Method 11) Touching 0.86 0.81 0.77 0.75 0.74 0.73 0.73 0.72 0.71 0.70 - - - -
Spaced* 0.91 0.89 0.88 0.87 0.87 - - - - - - - - -
Single layer single core on a perforated metal cable tray, touching (Method 11) Horizontal 0.90 0.85 - - - - - - - - - - - -
Vertical 0.85 - - - - - - - - - - - - -
Single layer multi-cores touching on ladder supports (Method 13) 0.86 0.82 0.80 0.79 0.78 0.78 0.78 0.77 - - - - - -

*Space means a clearance between adjacent surfaces of at least one cable diameter (De). Where the horizontal clearance between adjacent cables exceeds 2 De, no correction factor need be applied.

Note: