Fire Resisting Cable

Fire Resisting Cables

Current Rating and Voltage Drop

Multi-Core Cables having PVC Insulation, Armoured (Copper Conductor) 600/1000V

Current-Carrying Capacities (Amp) PVC/SWA/PVC Cables
Conductor cross-sectional area (mm²) Reference Method 1 (Clipped direct) Reference Method 11 (on a perforated horizontal cable tray) or Reference Method 13 (free air) Direct in Ground In Single Way Ducts
1 2-core cables single-phase ac or dc (Amp) 1 3- or 4-core cables 3-phase ac or dc (Amp) 1 2-core cable single-phase ac or dc (Amp) 1 3- or 4-core cable 3-phase ac or dc (Amp) 2 cores (Amp) 3 or 4 cores (Amp) 2 cores (Amp) 3 or 4 cores (Amp)
1.5 21 18 22 19 32 27 26 22
2.5 28 25 31 26 41 35 34 29
4 38 33 41 35 55 47 45 38
6 49 42 53 45 69 59 57 48
10 67 58 72 62 92 78 76 64
16 89 77 97 83 119 101 98 83
25 118 102 128 110 158 132 129 107
35 145 125 157 135 190 159 154 126
50 175 151 190 163 225 188 183 153
70 222 192 241 207 277 233 225 190
95 269 231 291 251 332 279 271 228
120 310 267 336 290 377 317 309 260
150 356 306 386 332 422 355 346 292
185 405 348 439 378 478 401 393 331
240 476 409 516 445 551 462 455 382
300 547 469 592 510 616 517 510 428
400 621 540 683 590 693 580 574 490

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

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

Group Rating Factor please refer to Table F & Table G

Voltage Drop (Per Amp Per Meter) PVC/SWA/PVC Cables
Conductor cross-sectional area (mm²) 2-core cable dc (mV/A/m) 2-core cable single-phase ac (mV/A/m) 3- or 4-core cable 3-phase ac (mV/A/m) Direct in Ground In Single Way Ducts
2-cores (mV/A/m) 3- or 4-cores (mV/A/m) 2-cores (mV/A/m) 3- or 4-cores (mV/A/m)
1.5 29 29 25 29 25 29 25
2.5 18 18 15 17 15 17 15
4 11 11 9.5 11 9.5 11 9.5
6 7.3 7.3 6.4 7.4 6.4 7.4 6.4
10 4.4 4.4 3.8 4.4 3.8 4.4 3.8
16 2.8 2.8 2.4 2.8 2.4 2.8 2.4
    r x z r x Z        
25 1.75 1.75 0.170 1.75 1.50 0.145 1.50 1.7 1.5 1.7 1.5
35 1.25 1.25 0.165 1.25 1.10 0.145 1.10 1.3 1.1 1.3 1.1
50 0.93 0.93 0.165 0.94 0.80 0.140 0.81 0.94 0.82 0.94 0.82
70 0.63 0.63 0.160 0.65 0.55 0.140 0.57 0.66 0.57 0.66 0.57
95 0.46 0.47 0.155 0.50 0.41 0.135 0.43 0.49 0.42 0.49 0.42
120 0.36 0.38 0.155 0.41 0.33 0.135 0.35 0.40 0.35 0.40 0.35
150 0.29 0.30 0.155 0.34 0.26 0.130 0.29 0.34 0.29 0.34 0.29
185 0.23 0.25 0.150 0.29 0.21 0.130 0.25 0.29 0.25 0.29 0.25
240 0.180 0.190 0.150 0.24 0.165 0.130 0.21 0.24 0.21 0.24 0.21
300 0.145 0.155 0.145 0.21 0.135 0.130 0.185 0.21 0.18 0.21 0.18
400 0.105 0.115 0.145 0.185 0.100 0.125 0.160 0.19 0.17 0.19 0.17

Note: r=conductor resistance at operating temperature

Z=impedance, x=reactance

Table A: Rating Factors for Other Ambient Air Temperatures (PVC Insulated)

Ambient Temperature 25℃ 30℃ 35℃ 40℃ 45℃ 50℃ 55℃ 60℃ 65℃ 70℃
Rating Factor 1.03 1.00 0.94 0.87 0.79 0.71 0.61 0.50 0.35 -

Table B: Rating Factors for Other Ground Temperatures (PVC Insulated)

Ground Temperature 10℃ 15℃ 20℃ 25℃ 30℃ 35℃ 40℃ 45℃ 50℃
Rating Factor 1.04 1.00 0.95 0.90 0.85 0.80 0.73 0.67 0.60

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: