Fire Resisting Cable

Fire Resisting Cables

Current Rating and Voltage Drop

Multi-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 and insulated wall etc) Reference Method 3 (Enclosed in conduit on a wall or cell, or in trunking) Reference Method 1 (Clipped direct) Reference Method 11 (on a perforated cable tray) or Reference Method 13 (free air)
1 2-core cable 1-phase ac or dc 1 3- or 4-core cable 3-phase ac 1 2-core cable 1-phase ac or dc 1 3- or 4-core cable 3-phase ac 1 2-core cable 1-phase ac or dc 1 3- or 4-core cable 3-phase ac 1 2-core cable 1-phase ac or dc 1 3- or 4-core cable 3-phase ac
1 mm² 2 A 3 A 4 A 5 A 6 A 7 A 8 A 9 A
1.5 18.5 16.5 22 19.5 24 22 26 23
2.5 25 22 30 26 33 30 36 32
4 33 30 40 35 45 40 49 42
6 42 38 51 44 58 52 63 54
10 57 51 69 60 80 71 86 75
16 76 68 91 80 107 96 115 100
25 99 89 119 105 138 119 149 127
35 121 109 146 128 171 147 185 158
50 145 130 175 154 209 179 225 192
70 183 164 221 194 269 229 289 246
95 220 197 265 233 328 278 352 298
120 253 227 305 268 382 322 410 346
150 290 259 334 300 441 371 473 399
185 329 295 384 340 506 424 542 456
240 386 346 459 398 599 500 641 538
300 442 396 532 455 693 576 741 621
400 - - 625 536 803 667 865 741

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-core cable dc 2-core cable 1-phase ac 3- or 4-core cable 3-phase ac
1 mm² 2 mV/A/m 3 mV/A/m 4 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 1.00 0.86 0.135 0.87
70 0.67 0.67 0.150 0.69 0.59 0.130 0.60
95 0.49 0.50 0.150 0.52 0.43 0.130 0.45
120 0.39 0.40 0.145 0.42 0.34 0.130 0.37
150 0.31 0.32 0.145 0.35 0.28 0.125 0.30
185 0.25 0.26 0.145 0.29 0.22 0.125 0.26
240 0.195 0.20 0.140 0.24 0.175 0.125 0.21
300 0.155 0.16 0.140 0.21 0.140 0.120 0.185
400 0.120 0.13 0.140 0.19 0.115 0.120 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: