The current carrying capacity of the aluminium cable is the maximum current that an aluminium cable of a given size can carry safely without getting damaged.
Aluminium and copper are the two widely used materials for the cable. The type of material used for the cable conductor mainly decides the current carrying capacity. Though, other factors also influence the current carrying capacity or amperage of the cable.
If we take the same size of copper and aluminium cable, the aluminium cable carries less current because the conductivity of the aluminium is less than the copper. The conductivity of copper is 5.98 X 107 s/m at 200 C, whereas the conductivity of aluminium is 3.5 X 107 s/m at 200 C. Thus, the conductivity of the aluminium is 0.58 times the conductivity of the copper.
Theoretically, aluminum cables carry 42 % less current than copper cables.
Considering all other conductivity influencing factors, practically an aluminum
cable carries about 35 % less current than a copper cable. However, copper
cable is about 55 % more costlier than aluminium cable.
Factors Affecting the Current Carrying Capacity of Aluminium cable
The following factors affect the conductivity of the conductor of the cable and eventually lower the current carrying capacity of the cable.
- Types of Insulation
- Exposure to direct solar radiation
- Ambient air temperature
- Groups of cables
- Number of cores in the cable
- Soil resistivity- for underground cables
- Ambient soil temperature – for underground cables
- Touching and non-touching cables
- Voltage level
- Types of voltage- AC or DC
- Conductor construction- solid or stranded
- Armoured or un-armoured
Aluminium Cable Current-Carrying Calculation Chart
XLPE Insulated Cable:
The current carrying capacities of XLPE insulated aluminium armoured cables are shown in the below table. Ref Specification: IS 7098 Part-1
| Current Carrying Capacity of 1.1 kV Aluminium Armoured cable (XLPE insulated) | |||
| Cable Size (Sq. mm) | Single-Core | Two-Core | Three-Core |
| 4 | 35 | 30 | 30 |
| 6 | 40 | 40 | 40 |
| 10 | 53 | 53 | 53 |
| 16 | 73 | 70 | 70 |
| 25 | 115 | 99 | 99 |
| 35 | 140 | 117 | 117 |
| 50 | 170 | 140 | 140 |
| 70 | 210 | 176 | 176 |
| 95 | 255 | 221 | 221 |
| 120 | 300 | 258 | 258 |
| 150 | 342 | 294 | 294 |
| 185 | 385 | 339 | 339 |
| 240 | 450 | 402 | 402 |
| 300 | 519 | 461 | 461 |
PVC Insulated Cable:
The current carrying capacities of PVC-insulated aluminium cables are shown in the below table. Ref Specification: IS 1554 Part-1
| Current Carrying Capacity of 1.1 kV Aluminium Armoured cable (PVC insulated) | |||
| Cable Size (Sq. mm) | Single-Core | Two-Core | Three-Core |
| 4 | 27 | 27 | 23 |
| 6 | 35 | 35 | 30 |
| 10 | 47 | 47 | 40 |
| 16 | 64 | 59 | 51 |
| 25 | 84 | 78 | 70 |
| 35 | 105 | 99 | 86 |
| 50 | 130 | 125 | 105 |
| 70 | 153 | 150 | 130 |
| 95 | 190 | 185 | 155 |
| 120 | 220 | 210 | 180 |
| 150 | 250 | 240 | 205 |
| 185 | 290 | 275 | 240 |
| 240 | 335 | 325 | 280 |
| 300 | 380 | 365 | 315 |
The XLPE cables can be operated up to 900C while the PVC cable’s maximum operating temperature is 700C. Therefore, the current carrying capacity of the XLPE insulated aluminium cable is more than the PVC insulated cable.
The above given current carrying capacities of the cables are taken for the cable in air. The cable de-rating factor needs to be taken while selecting the cable size for your applications.
