Handbook of Electrical Engineering

CABLES, WIRES AND CABLE INSTALLATION PRACTICES 201

Table 9.12. Land based installations. 600/1000 V. Cu/PVC/PVC/AWA/PVC single core

Nominal Air Air Ducts Direct buried Notes
conductor trefoil 3 trefoil
area (mm^2 ) horizontally trefoil^33
spaced horizontally horizontally
touching spaced
50 193 247 193 203 193 202 Thermal resistivity of
70 243 307 229 248 233 243 soil is 1.2◦Cm/W
95 298 372 269 297 277 288 Ambient air
120 347 429 302 337 315 326 temperature is 30◦C
150 395 472 324 376 347 355 Depth of laying cables
185 452 528 356 423 386 393 is 0.5 m
240 532 606 398 485 441 443 Standard ground
300 607 672 435 542 490 486 temperature is 15◦C
400 690 719 460 600 533 516 Conductor surface
temperature is 70◦C

Ambient air temperature◦C2530354045505560
Rating factorKairfor cables
laid in air

1.02 1.0 0.94 0.87 0.79 0.71 0.61 0.50

Table 9.13. Land based installations. 600/1000 V. Cu/PVC/PVC/AWA/PVC single core Cu/PVC/PVC/SWA/
PVC 3 and 4 cores

Single cores in trefoil 3 and 4 cores Approximate armouring

resistance

Nominal conductor

Resistance Reactance Resistance Reactance AWA SWA

area (mm^2 )

at 70◦C at50 Hz at70◦C at50 Hz at80◦Cat80◦C

(ohm/km) (ohm/km) (ohm/km) (ohm/km) (ohms/km) (ohms/km)

1.5 14.451 0.104 2.39 11.40

2.5 8.868 0.101 1.99 9.48

4 5.518 0.099 1.16 5.52

6 3.688 0.094 1.03 4.92

10 2.186 0.090 0.857 4.08

16 1.380 0.087 0.554 2.64

25 0.870 0.084 0.529 2.52

35 0.627 0.081 0.479 2.28

50 0.464 0.112 0.464 0.081 0.328 1.56

70 0.321 0.107 0.321 0.079 0.302 1.44

95 0.232 0.103 0.232 0.077 0.247 1.176

120 0.184 0.103 0.184 0.076 0.179 0.852

150 0.150 0.101 0.150 0.076 0.164 0.780

185 0.121 0.099 0.121 0.076 0.149 0.708

240 0.0927 0.096 0.0929 0.075 0.131 0.624

300 0.0751 0.094 0.0752 0.074 0.118 0.564

400 0.0600 0.091 0.0604 0.074 0.0857 0.408