SWA Cable Current and Sizing Charts

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Use this page to find the Current Rating for XLPE/PVC/SWA/PVC ARMOURED CABLE

SWA Current Carrying Capacity

CURRENT CARRYING CAPACITY (AMPS)
Clipped Direct In Free Air Direct in Ground or Ducting
Nominal Conductor Area 2 Core 3 & 4 Core Nominal Conductor Area 2 Core 3 & 4 Core Nominal Conductor Area 2 Core 3 & 4 Core
1.5mm² 27 23 1.5mm² 29 25 1.5mm² 25 21
2.5mm² 36 31 2.5mm² 39 33 2.5mm² 33 28
4.0mm² 49 42 4.0mm² 52 44 4.0mm² 43 36
6.0mm² 62 53 6.0mm² 66 56 6.0mm² 53 44
10.0mm² 85 73 10.0mm² 90 78 10.0mm² 71 58
16.0mm² 110 94 16.0mm² 115 99 16.0mm² 91 75
25.0mm² 146 124 25.0mm² 152 131 25.0mm² 116 96
35.0mm² 180 154 35.0mm² 188 162 35.0mm² 139 115
50.0mm² 219 187 50.0mm² 228 197 50.0mm² 164 135
70.0mm² 279 238 70.0mm² 291 251 70.0mm² 203 167
95.0mm² 338 289 95.0mm² 354 304 95.0mm² 239 197
120.0mm² 392 335 120.0mm² 410 353 120.0mm² 271 223
150.0mm² 451 386 150.0mm² 472 406 150.0mm² 306 251
185.0mm² 515 441 185.0mm² 539 463 185.0mm² 343 281
240.0mm² 607 520 240.0mm² 636 546 240.0mm² 395 324
300.0mm² 698 599 300.0mm² 732 628 300.0mm² 446 365
400.0mm² 787 673 400.0mm² 847 728 400.0mm² – –
  • Standard depth of laying: 0.5m
  • Thermal resistivity of soil: 1.2ºC m/W
  • Standard ground temperature: 20ºC
  • Ambient air temperature: 30ºC
  • Maximum conductor temperature: 90ºC

For 2 core – single phase a.c., 3 & 4 core – three phase a.c. – ratings do not apply if the cable is protected by a semi-enclosed fuse to BS3036.

For cables of 5 cores and above it is assumed only 2 cores are loaded simultaneously (ie live and neutral) and the 2 core rating should be taken. In instances where several cores are loaded simultaneously, the following rating factors should be applied to the 2 core current rating.

Rating Factors

Number of cores 2 3 4 5 6 7 10 12 –
Factor 1.0 0.87 0.78 0.72 0.67 0.63 0.56 0.53 –
Number of cores 14 19 24 27 30 37 44 46 48
Factor 0.51 0.45 0.42 0.40 0.39 0.36 0.34 0.33 0.33
If cables laid in air temperatures other than those specified the following ratings should be applied:
Ambient air temperature 30ºC 25 30 35 40 45 50 55
Rating Factor 1.0 0.96 0.92 0.88 0.83 0.78 0.73
If cables laid in ground and single way ducts with temperatures other than those specified the following ratings should be applied:
Ambient air temperature 30ºC 10 15 20 25 30 35 40
Rating Factor 1.03 1.0 0.97 0.93 0.89 0.86 0.82
 

Volt Drop

VOLTAGE DROPS (AMPS PER METRE)
Conductor Cross Sectional Area Two Core Cable
d.c.		 Two Core Cable Single Phase
a.c.		 Three or Four Cable Three Phase
a.c.
1.5mm² 31mV 31mV 27mV
2.5mm² 19mV 19mV 16mV
4.0mm² 12mV 12mV 10mV
6.0mm² 7.9mV 7.9mV 6.8mV
10.0mm² 4.7mV 4.7mV 4.0mV
16.0mm² 2.9mV 2.9mV 2.5mV
    r x z r x z
25.0mm² 1.85mV 1.85mV 0.160mV 1.90mV 1.60mV 0.140mV 1.65mV
35.0mm² 1.35mV 1.35mV 0.155mV 1.35mV 1.15mV 0.135mV 1.15mV
50.0mm² 0.98mV 0.99mV 0.155mV 1.00mV 0.86mV 0.135mV 0.87mV
70.0mm² 0.67mV 0.67mV 0.150mV 0.69mV 0.59mV 0.130mV 0.60mV
95.0mm² 0.49mV 0.50mV 0.150mV 0.52mV 0.43mV 0.130mV 0.45mV
120.0mm² 0.39mV 0.40mV 0.145mV 0.42mV 0.34mV 0.130mV 0.37mV
150.0mm² 0.31mV 0.32mV 0.145mV 0.35mV 0.28mV 0.125mV 0.30mV
185.0mm² 0.25mV 0.26mV 0.145mV 0.29mV 0.22mV 0.125mV 0.26mV
240.0mm² 0.195mV 0.20mV 0.140mV 0.24mV 0.175mV 0.125mV 0.21mV
300.0mm² 0.155mV 0.16mV 0.140mV 0.21mV 0.140mV 0.120mV 0.185mV
400.0mm² 0.120mV 0.13mV 0.145mV 0.195mV 0.115mV 0.125mV 0.170mV

If you need any help with cable design calculations and/or overall system design, we offer a complete service utilising the latest design software to ensure compliance and optimise costs, so if interested, please get in touch here.

Alternatively, visit SparkBench for a suite of tools for electricians and designers.

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